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defmodule Ecto.Repo do
@moduledoc """
Defines a repository.
A repository maps to an underlying data store, controlled by the
adapter. For example, Ecto ships with a Postgres adapter that
stores data into a PostgreSQL database.
When used, the repository expects the `:otp_app` and `:adapter` as
option. The `:otp_app` should point to an OTP application that has
the repository configuration. For example, the repository:
defmodule Repo do
use Ecto.Repo,
otp_app: :my_app,
adapter: Ecto.Adapters.Postgres
end
Could be configured with:
config :my_app, Repo,
database: "ecto_simple",
username: "postgres",
password: "postgres",
hostname: "localhost"
Most of the configuration that goes into the `config` is specific
to the adapter. For this particular example, you can check
[`Ecto.Adapters.Postgres`](https://hexdocs.pm/ecto_sql/Ecto.Adapters.Postgres.html)
for more information. In spite of this, the following configuration values
are shared across all adapters:
* `:name`- The name of the Repo supervisor process
* `:priv` - the directory where to keep repository data, like
migrations, schema and more. Defaults to "priv/YOUR_REPO".
It must always point to a subdirectory inside the priv directory
* `:url` - an URL that specifies storage information. Read below
for more information
* `:log` - the log level used when logging the query with Elixir's
Logger. If false, disables logging for that repository.
Defaults to `:debug`
* `:pool_size` - the size of the pool used by the connection module.
Defaults to `10`
* `:telemetry_prefix` - we recommend adapters to publish events
using the `Telemetry` library. By default, the telemetry prefix
is based on the module name, so if your module is called
`MyApp.Repo`, the prefix will be `[:my_app, :repo]`. See the
"Telemetry Events" section to see which events we recommend
adapters to publish
## URLs
Repositories by default support URLs. For example, the configuration
above could be rewritten to:
config :my_app, Repo,
url: "ecto://postgres:postgres@localhost/ecto_simple"
The schema can be of any value. The path represents the database name
while options are simply merged in.
URL can include query parameters to override shared and adapter-specific
options, like `ssl`, `timeout` and `pool_size`. The following example
shows how to pass these configuration values:
config :my_app, Repo,
url: "ecto://postgres:postgres@localhost/ecto_simple?ssl=true&pool_size=10"
In case the URL needs to be dynamically configured, for example by
reading a system environment variable, such can be done via the
`c:init/2` repository callback:
def init(_type, config) do
{:ok, Keyword.put(config, :url, System.get_env("DATABASE_URL"))}
end
## Shared options
Almost all of the repository functions outlined in this module accept the following
options:
* `:timeout` - The time in milliseconds to wait for the query call to
finish. `:infinity` will wait indefinitely (default: 15000)
* `:log` - When false, does not log the query
* `:telemetry_event` - The telemetry event name to dispatch the event under.
See the next section for more information
### Telemetry events
We recommend adapters to publish certain `Telemetry` events listed below.
Those events will use the `:telemetry_prefix` outlined above which defaults
to `[:my_app, :repo]`.
For instance, to receive all query events published by a repository called
`MyApp.Repo`, one would define a module:
defmodule MyApp.Telemetry do
def handle_event([:my_app, :repo, :query], measurements, metadata, config) do
IO.inspect binding()
end
end
Then, in the `Application.start/2` callback, attach the handler to this event using
a unique handler id:
:ok = :telemetry.attach("my-app-handler-id", [:my_app, :repo, :query], &MyApp.Telemetry.handle_event/4, %{})
For details, see [the telemetry documentation](https://hexdocs.pm/telemetry/).
Below we list all events developers should expect from Ecto. All examples below consider
a repository named `MyApp.Repo`:
#### `[:my_app, :repo, :query]`
This event should be invoked on every query sent to the adapter, including
queries that are related to the transaction management.
The `:measurements` map will include the following, all given in the
`:native` time unit:
* `:idle_time` - the time the connection spent waiting before being checked out for the query
* `:queue_time` - the time spent waiting to check out a database connection
* `:query_time` - the time spent executing the query
* `:decode_time` - the time spent decoding the data received from the database
* `:total_time` - the sum of the other measurements
All measurements are given in the `:native` time unit. You can read more
about it in the docs for `System.convert_time_unit/3`.
A `:metadata` map is also sent, including parameters, source, the query
string, the repo it was run by, and the query result.
## Read-only repositories
You can mark a repository as read-only by passing the `:read_only`
flag on `use`:
use Ecto.Repo, otp_app: ..., adapter: ..., read_only: true
By passing the `:read_only` option, none of the functions that perform
write operations, such as `c:insert/2`, `c:insert_all/3`, `c:update_all/3`,
and friends will be defined.
"""
@type t :: module
@doc false
defmacro __using__(opts) do
quote bind_quoted: [opts: opts] do
@behaviour Ecto.Repo
{otp_app, adapter, behaviours} =
Ecto.Repo.Supervisor.compile_config(__MODULE__, opts)
@otp_app otp_app
@adapter adapter
@default_dynamic_repo opts[:default_dynamic_repo] || __MODULE__
@read_only opts[:read_only] || false
@before_compile adapter
@aggregates [:count, :avg, :max, :min, :sum]
def config do
{:ok, config} = Ecto.Repo.Supervisor.runtime_config(:runtime, __MODULE__, @otp_app, [])
config
end
def __adapter__ do
@adapter
end
def child_spec(opts) do
%{
id: __MODULE__,
start: {__MODULE__, :start_link, [opts]},
type: :supervisor
}
end
def start_link(opts \\ []) do
Ecto.Repo.Supervisor.start_link(__MODULE__, @otp_app, @adapter, opts)
end
def stop(timeout \\ 5000) do
Supervisor.stop(get_dynamic_repo(), :normal, timeout)
end
def load(schema_or_types, data) do
Ecto.Repo.Schema.load(@adapter, schema_or_types, data)
end
def checkout(fun, opts \\ []) when is_function(fun) do
{adapter, meta} = Ecto.Repo.Registry.lookup(get_dynamic_repo())
adapter.checkout(meta, opts, fun)
end
@compile {:inline, get_dynamic_repo: 0}
def get_dynamic_repo() do
Process.get({__MODULE__, :dynamic_repo}, @default_dynamic_repo)
end
def put_dynamic_repo(dynamic) when is_atom(dynamic) or is_pid(dynamic) do
Process.put({__MODULE__, :dynamic_repo}, dynamic) || @default_dynamic_repo
end
## Transactions
if Ecto.Adapter.Transaction in behaviours do
def transaction(fun_or_multi, opts \\ []) do
Ecto.Repo.Transaction.transaction(__MODULE__, get_dynamic_repo(), fun_or_multi, opts)
end
def in_transaction? do
Ecto.Repo.Transaction.in_transaction?(get_dynamic_repo())
end
@spec rollback(term) :: no_return
def rollback(value) do
Ecto.Repo.Transaction.rollback(get_dynamic_repo(), value)
end
end
## Schemas
if Ecto.Adapter.Schema in behaviours and not @read_only do
def insert(struct, opts \\ []) do
Ecto.Repo.Schema.insert(__MODULE__, get_dynamic_repo(), struct, opts)
end
def update(struct, opts \\ []) do
Ecto.Repo.Schema.update(__MODULE__, get_dynamic_repo(), struct, opts)
end
def insert_or_update(changeset, opts \\ []) do
Ecto.Repo.Schema.insert_or_update(__MODULE__, get_dynamic_repo(), changeset, opts)
end
def delete(struct, opts \\ []) do
Ecto.Repo.Schema.delete(__MODULE__, get_dynamic_repo(), struct, opts)
end
def insert!(struct, opts \\ []) do
Ecto.Repo.Schema.insert!(__MODULE__, get_dynamic_repo(), struct, opts)
end
def update!(struct, opts \\ []) do
Ecto.Repo.Schema.update!(__MODULE__, get_dynamic_repo(), struct, opts)
end
def insert_or_update!(changeset, opts \\ []) do
Ecto.Repo.Schema.insert_or_update!(__MODULE__, get_dynamic_repo(), changeset, opts)
end
def delete!(struct, opts \\ []) do
Ecto.Repo.Schema.delete!(__MODULE__, get_dynamic_repo(), struct, opts)
end
def insert_all(schema_or_source, entries, opts \\ []) do
Ecto.Repo.Schema.insert_all(__MODULE__, get_dynamic_repo(), schema_or_source, entries, opts)
end
end
## Queryable
if Ecto.Adapter.Queryable in behaviours do
if not @read_only do
def update_all(queryable, updates, opts \\ []) do
Ecto.Repo.Queryable.update_all(get_dynamic_repo(), queryable, updates, opts)
end
def delete_all(queryable, opts \\ []) do
Ecto.Repo.Queryable.delete_all(get_dynamic_repo(), queryable, opts)
end
end
def all(queryable, opts \\ []) do
Ecto.Repo.Queryable.all(get_dynamic_repo(), queryable, opts)
end
def stream(queryable, opts \\ []) do
Ecto.Repo.Queryable.stream(get_dynamic_repo(), queryable, opts)
end
def get(queryable, id, opts \\ []) do
Ecto.Repo.Queryable.get(get_dynamic_repo(), queryable, id, opts)
end
def get!(queryable, id, opts \\ []) do
Ecto.Repo.Queryable.get!(get_dynamic_repo(), queryable, id, opts)
end
def get_by(queryable, clauses, opts \\ []) do
Ecto.Repo.Queryable.get_by(get_dynamic_repo(), queryable, clauses, opts)
end
def get_by!(queryable, clauses, opts \\ []) do
Ecto.Repo.Queryable.get_by!(get_dynamic_repo(), queryable, clauses, opts)
end
def one(queryable, opts \\ []) do
Ecto.Repo.Queryable.one(get_dynamic_repo(), queryable, opts)
end
def one!(queryable, opts \\ []) do
Ecto.Repo.Queryable.one!(get_dynamic_repo(), queryable, opts)
end
def aggregate(queryable, aggregate, opts \\ [])
def aggregate(queryable, aggregate, opts)
when aggregate in [:count] and is_list(opts) do
Ecto.Repo.Queryable.aggregate(get_dynamic_repo(), queryable, aggregate, opts)
end
def aggregate(queryable, aggregate, field)
when aggregate in @aggregates and is_atom(field) do
Ecto.Repo.Queryable.aggregate(get_dynamic_repo(), queryable, aggregate, field, [])
end
def aggregate(queryable, aggregate, field, opts)
when aggregate in @aggregates and is_atom(field) and is_list(opts) do
Ecto.Repo.Queryable.aggregate(get_dynamic_repo(), queryable, aggregate, field, opts)
end
def exists?(queryable, opts \\ []) do
Ecto.Repo.Queryable.exists?(get_dynamic_repo(), queryable, opts)
end
def preload(struct_or_structs_or_nil, preloads, opts \\ []) do
Ecto.Repo.Preloader.preload(struct_or_structs_or_nil, get_dynamic_repo(), preloads, opts)
end
def prepare_query(operation, query, opts), do: {query, opts}
defoverridable prepare_query: 3
end
end
end
## User callbacks
@optional_callbacks init: 2
@doc """
A callback executed when the repo starts or when configuration is read.
The first argument is the context the callback is being invoked. If it
is called because the Repo supervisor is starting, it will be `:supervisor`.
It will be `:runtime` if it is called for reading configuration without
actually starting a process.
The second argument is the repository configuration as stored in the
application environment. It must return `{:ok, keyword}` with the updated
list of configuration or `:ignore` (only in the `:supervisor` case).
"""
@callback init(context :: :supervisor | :runtime, config :: Keyword.t()) ::
{:ok, Keyword.t()} | :ignore
## Ecto.Adapter
@doc """
Returns the adapter tied to the repository.
"""
@callback __adapter__ :: Ecto.Adapter.t()
@doc """
Returns the adapter configuration stored in the `:otp_app` environment.
If the `c:init/2` callback is implemented in the repository,
it will be invoked with the first argument set to `:runtime`.
"""
@callback config() :: Keyword.t()
@doc """
Starts any connection pooling or supervision and return `{:ok, pid}`
or just `:ok` if nothing needs to be done.
Returns `{:error, {:already_started, pid}}` if the repo is already
started or `{:error, term}` in case anything else goes wrong.
## Options
See the configuration in the moduledoc for options shared between adapters,
for adapter-specific configuration see the adapter's documentation.
"""
@callback start_link(opts :: Keyword.t()) ::
{:ok, pid}
| {:error, {:already_started, pid}}
| {:error, term}
@doc """
Shuts down the repository.
"""
@callback stop(timeout) :: :ok
@doc """
Checks out a connection for the duration of the function.
It returns the result of the function. This is useful when
you need to perform multiple operations against the repository
in a row and you want to avoid checking out the connection
multiple times.
`checkout/2` and `transaction/2` can be combined and nested
multiple times. If `checkout/2` is called inside the function
of another `checkout/2` call, the function is simply executed,
without checking out a new connection.
## Options
See the "Shared options" section at the module documentation for more options.
"""
@callback checkout((() -> result), opts :: Keyword.t()) :: result when result: var
@doc """
Loads `data` into a struct or a map.
The first argument can be a a schema module, or a
map (of types) and determines the return value:
a struct or a map, respectively.
The second argument `data` specifies fields and values that are to be loaded.
It can be a map, a keyword list, or a `{fields, values}` tuple.
Fields can be atoms or strings.
Fields that are not present in the schema (or `types` map) are ignored.
If any of the values has invalid type, an error is raised.
## Examples
iex> MyRepo.load(User, %{name: "Alice", age: 25})
%User{name: "Alice", age: 25}
iex> MyRepo.load(User, [name: "Alice", age: 25])
%User{name: "Alice", age: 25}
`data` can also take form of `{fields, values}`:
iex> MyRepo.load(User, {[:name, :age], ["Alice", 25]})
%User{name: "Alice", age: 25, ...}
The first argument can also be a `types` map:
iex> types = %{name: :string, age: :integer}
iex> MyRepo.load(types, %{name: "Alice", age: 25})
%{name: "Alice", age: 25}
This function is especially useful when parsing raw query results:
iex> result = Ecto.Adapters.SQL.query!(MyRepo, "SELECT * FROM users", [])
iex> Enum.map(result.rows, &MyRepo.load(User, {result.columns, &1}))
[%User{...}, ...]
"""
@callback load(
module_or_map :: module | map(),
data :: map() | Keyword.t() | {list, list}
) :: Ecto.Schema.t() | map()
@doc """
Returns the atom name or pid of the current repository.
See `c:put_dynamic_repo/1` for more information.
"""
@callback get_dynamic_repo() :: atom() | pid()
@doc """
Sets the dynamic repository to be used in further interactions.
Sometimes you may want a single Ecto repository to talk to
many different database instances. By default, when you call
`MyApp.Repo.start_link/1`, it will start a repository with
name `MyApp.Repo`. But if you want to start multiple repositories,
you can give each of them a different name:
MyApp.Repo.start_link(name: :tenant_foo, hostname: "foo.example.com")
MyApp.Repo.start_link(name: :tenant_bar, hostname: "bar.example.com")
You can also start repositories without names by explicitly
setting the name to nil:
MyApp.Repo.start_link(name: nil, hostname: "temp.example.com")
However, once the repository is started, you can't directly interact with
it, since all operations in `MyApp.Repo` are sent by default to the repository
named `MyApp.Repo`. You can change the default repo at compile time with:
use Ecto.Repo, default_dynamic_repo: :name_of_repo
Or you can change it anytime at runtime by calling `put_dynamic_repo/1`:
MyApp.Repo.put_dynamic_repo(:tenant_foo)
From this moment on, all future queries done by the current process will
run on `:tenant_foo`.
**Note this feature is experimental and may be changed or removed in future
releases.**
"""
@callback put_dynamic_repo(atom() | pid()) :: atom() | pid()
## Ecto.Adapter.Queryable
@optional_callbacks get: 3, get!: 3, get_by: 3, get_by!: 3, aggregate: 3, aggregate: 4, exists?: 2,
one: 2, one!: 2, preload: 3, all: 2, stream: 2, update_all: 3, delete_all: 2
@doc """
Fetches a single struct from the data store where the primary key matches the
given id.
Returns `nil` if no result was found. If the struct in the queryable
has no or more than one primary key, it will raise an argument error.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
## Example
MyRepo.get(Post, 42)
MyRepo.get(Post, 42, prefix: "public")
"""
@callback get(queryable :: Ecto.Queryable.t(), id :: term, opts :: Keyword.t()) ::
Ecto.Schema.t() | nil
@doc """
Similar to `c:get/3` but raises `Ecto.NoResultsError` if no record was found.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
## Example
MyRepo.get!(Post, 42)
MyRepo.get!(Post, 42, prefix: "public")
"""
@callback get!(queryable :: Ecto.Queryable.t(), id :: term, opts :: Keyword.t()) ::
Ecto.Schema.t()
@doc """
Fetches a single result from the query.
Returns `nil` if no result was found. Raises if more than one entry.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
## Example
MyRepo.get_by(Post, title: "My post")
MyRepo.get_by(Post, [title: "My post"], prefix: "public")
"""
@callback get_by(
queryable :: Ecto.Queryable.t(),
clauses :: Keyword.t() | map,
opts :: Keyword.t()
) :: Ecto.Schema.t() | nil
@doc """
Similar to `c:get_by/3` but raises `Ecto.NoResultsError` if no record was found.
Raises if more than one entry.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
## Example
MyRepo.get_by!(Post, title: "My post")
MyRepo.get_by!(Post, [title: "My post"], prefix: "public")
"""
@callback get_by!(
queryable :: Ecto.Queryable.t(),
clauses :: Keyword.t() | map,
opts :: Keyword.t()
) :: Ecto.Schema.t()
@doc """
Calculate the given `aggregate`.
If the query has a limit, offset or distinct set, it will be
automatically wrapped in a subquery in order to return the
proper result.
Any preload or select in the query will be ignored in favor of
the column being aggregated.
The aggregation will fail if any `group_by` field is set.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
## Examples
# Returns the number of visits per blog post
Repo.aggregate(Post, :count)
# Returns the number of visits per blog post in the "private" schema path
# (in Postgres) or database (in MySQL)
Repo.aggregate(Post, :count, prefix: "private")
"""
@callback aggregate(
queryable :: Ecto.Queryable.t(),
aggregate :: :count,
opts :: Keyword.t()
) :: term | nil
@doc """
Calculate the given `aggregate` over the given `field`.
See `aggregate/2` for general considerations and options.
## Examples
# Returns the number of visits per blog post
Repo.aggregate(Post, :count, :visits)
# Returns the number of visits per blog post in the "private" schema path
# (in Postgres) or database (in MySQL)
Repo.aggregate(Post, :count, :visits, prefix: "private")
# Returns the average number of visits for the top 10
query = from Post, limit: 10
Repo.aggregate(query, :avg, :visits)
"""
@callback aggregate(
queryable :: Ecto.Queryable.t(),
aggregate :: :avg | :count | :max | :min | :sum,
field :: atom,
opts :: Keyword.t()
) :: term | nil
@doc """
Checks if there exists an entry that matches the given query.
Returns a boolean.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
## Examples
# checks if any posts exist
Repo.exists?(Post)
# checks if any posts exist in the "private" schema path (in Postgres) or
# database (in MySQL)
Repo.exists?(Post, schema: "private")
# checks if any post with a like count greater than 10 exists
query = from p in Post, where: p.like_count > 10
Repo.exists?(query)
"""
@callback exists?(queryable :: Ecto.Queryable.t(), opts :: Keyword.t()) :: boolean()
@doc """
Fetches a single result from the query.
Returns `nil` if no result was found. Raises if more than one entry.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
## Examples
Repo.one(Post)
Repo.one(from p in Post, where: p.like_count > 10)
query = from p in Post, where: p.like_count > 10
Repo.one(query, prefix: "private")
"""
@callback one(queryable :: Ecto.Queryable.t(), opts :: Keyword.t()) ::
Ecto.Schema.t() | nil
@doc """
Similar to `c:one/2` but raises `Ecto.NoResultsError` if no record was found.
Raises if more than one entry.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
"""
@callback one!(queryable :: Ecto.Queryable.t(), opts :: Keyword.t()) ::
Ecto.Schema.t()
@doc """
Preloads all associations on the given struct or structs.
This is similar to `Ecto.Query.preload/3` except it allows
you to preload structs after they have been fetched from the
database.
In case the association was already loaded, preload won't attempt
to reload it.
## Options
* `:force` - By default, Ecto won't preload associations that
are already loaded. By setting this option to true, any existing
association will be discarded and reloaded.
* `:in_parallel` - If the preloads must be done in parallel. It can
only be performed when we have more than one preload and the
repository is not in a transaction. Defaults to `true`.
* `:prefix` - the prefix to fetch preloads from. By default, queries
will use the same prefix as the one in the given collection. This
option allows the prefix to be changed.
See the "Shared options" section at the module documentation for more options.
## Examples
# Use a single atom to preload an association
posts = Repo.preload posts, :comments
# Use a list of atoms to preload multiple associations
posts = Repo.preload posts, [:comments, :authors]
# Use a keyword list to preload nested associations as well
posts = Repo.preload posts, [comments: [:replies, :likes], authors: []]
# Use a keyword list to customize how associations are queried
posts = Repo.preload posts, [comments: from(c in Comment, order_by: c.published_at)]
# Use a two-element tuple for a custom query and nested association definition
query = from c in Comment, order_by: c.published_at
posts = Repo.preload posts, [comments: {query, [:replies, :likes]}]
The query given to preload may also preload its own associations.
"""
@callback preload(structs_or_struct_or_nil, preloads :: term, opts :: Keyword.t()) ::
structs_or_struct_or_nil
when structs_or_struct_or_nil: [Ecto.Schema.t()] | Ecto.Schema.t() | nil
@doc """
A user customizable callback invoked for query-based operations.
This callback can be used to further modify the query and options
before it is transformed and sent to the database.
This callback is invoked for all query APIs, including the `stream`
function, but it is not invoked for `insert_all` nor any of the
schema functions.
## Examples
Let's say you want to filter out records that were "soft-deleted" (have `deleted_at`
column set) from all operations unless an admin is running the query; you can define
the callback like this:
@impl true
def prepare_query(_operation, query, opts) do
if opts[:admin] do
{query, opts}
else
query = from(x in query, where: is_nil(x.deleted_at))
{query, opts}
end
end
And then execute the query:
Repo.all(query) # only non-deleted records are returned
Repo.all(query, admin: true) # all records are returned
"""
@callback prepare_query(operation, query :: Ecto.Query.t(), opts :: Keyword.t()) ::
{Ecto.Query.t(), Keyword.t()}
when operation: :all | :update_all | :delete_all | :stream
@doc """
Fetches all entries from the data store matching the given query.
May raise `Ecto.QueryError` if query validation fails.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
See the "Shared options" section at the module documentation for more options.
## Example
# Fetch all post titles
query = from p in Post,
select: p.title
MyRepo.all(query)
"""
@callback all(queryable :: Ecto.Queryable.t(), opts :: Keyword.t()) :: [Ecto.Schema.t()]
@doc """
Returns a lazy enumerable that emits all entries from the data store
matching the given query.
SQL adapters, such as Postgres and MySQL, can only enumerate a stream
inside a transaction.
May raise `Ecto.QueryError` if query validation fails.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This will be applied to all `from`
and `join`s in the query that did not have a prefix previously given
either via the `:prefix` option on `join`/`from` or via `@schema_prefix`
in the schema. For more information see the "Query Prefix" section of the
`Ecto.Query` documentation.
* `:max_rows` - The number of rows to load from the database as we stream.
It is supported at least by Postgres and MySQL and defaults to 500.
See the "Shared options" section at the module documentation for more options.
## Example
# Fetch all post titles
query = from p in Post,
select: p.title
stream = MyRepo.stream(query)
MyRepo.transaction(fn() ->
Enum.to_list(stream)
end)
"""
@callback stream(queryable :: Ecto.Queryable.t(), opts :: Keyword.t()) :: Enum.t()
@doc """
Updates all entries matching the given query with the given values.
It returns a tuple containing the number of entries and any returned
result as second element. The second element is `nil` by default
unless a `select` is supplied in the update query. Note, however,
not all databases support returning data from UPDATEs.
Keep in mind this `update_all` will not update autogenerated
fields like the `updated_at` columns.
See `Ecto.Query.update/3` for update operations that can be
performed on fields.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This overrides the prefix set
in the query and any `@schema_prefix` set in the schema.
See the "Shared options" section at the module documentation for
remaining options.
## Examples
MyRepo.update_all(Post, set: [title: "New title"])
MyRepo.update_all(Post, inc: [visits: 1])
from(p in Post, where: p.id < 10, select: p.visits)
|> MyRepo.update_all(set: [title: "New title"])
from(p in Post, where: p.id < 10, update: [set: [title: "New title"]])
|> MyRepo.update_all([])
from(p in Post, where: p.id < 10, update: [set: [title: ^new_title]])
|> MyRepo.update_all([])
from(p in Post, where: p.id < 10, update: [set: [title: fragment("upper(?)", ^new_title)]])
|> MyRepo.update_all([])
"""
@callback update_all(
queryable :: Ecto.Queryable.t(),
updates :: Keyword.t(),
opts :: Keyword.t()
) :: {integer, nil | [term]}
@doc """
Deletes all entries matching the given query.
It returns a tuple containing the number of entries and any returned
result as second element. The second element is `nil` by default
unless a `select` is supplied in the delete query. Note, however,
not all databases support returning data from DELETEs.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This overrides the prefix set
in the query and any `@schema_prefix` set in the schema.
See the "Shared options" section at the module documentation for
remaining options.
## Examples
MyRepo.delete_all(Post)
from(p in Post, where: p.id < 10) |> MyRepo.delete_all
"""
@callback delete_all(queryable :: Ecto.Queryable.t(), opts :: Keyword.t()) ::
{integer, nil | [term]}
## Ecto.Adapter.Schema
@optional_callbacks insert_all: 3, insert: 2, insert!: 2, update: 2, update!: 2,
delete: 2, delete!: 2, insert_or_update: 2, insert_or_update!: 2,
prepare_query: 3
@doc """
Inserts all entries into the repository.
It expects a schema module (`MyApp.User`) or a source (`"users"`) or
both (`{"users", MyApp.User}`) as the first argument. The second
argument is a list of entries to be inserted, either as keyword
lists or as maps. The keys of the entries are the field names as
atoms and the value should be the respective value for the field
type or, optionally, an `Ecto.Query` that returns a single entry
with a single value.
It returns a tuple containing the number of entries
and any returned result as second element. If the database
does not support RETURNING in INSERT statements or no
return result was selected, the second element will be `nil`.
When a schema module is given, the entries given will be properly dumped
before being sent to the database. If the schema contains an
autogenerated ID field, it will be handled either at the adapter
or the storage layer. However any other autogenerated value, like
timestamps, won't be autogenerated when using `c:insert_all/3`.
This is by design as this function aims to be a more direct way
to insert data into the database without the conveniences of
`c:insert/2`. This is also consistent with `c:update_all/3` that
does not handle timestamps as well.
It is also not possible to use `insert_all` to insert across multiple
tables, therefore associations are not supported.
If a source is given, without a schema module, the given fields are passed
as is to the adapter.
## Options
* `:returning` - selects which fields to return. When `true`,
returns all fields in the given schema. May be a list of
fields, where a struct is still returned but only with the
given fields. Or `false`, where nothing is returned (the default).
This option is not supported by all databases.
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This overrides the prefix set
in the query and any `@schema_prefix` set in the schema.
* `:on_conflict` - It may be one of `:raise` (the default), `:nothing`,
`:replace_all`, `:replace_all_except_primary_key`, `{:replace, fields}`,
a keyword list of update instructions or an `Ecto.Query`
query for updates. See the "Upserts" section for more information.
* `:conflict_target` - A list of column names to verify for conflicts.
It is expected those columns to have unique indexes on them that may conflict.
If none is specified, the conflict target is left up to the database.
It may also be `{:constraint, constraint_name_as_atom}` in databases
that support the "ON CONSTRAINT" expression, such as PostgreSQL, or
`{:unsafe_fragment, binary_fragment}` to pass any expression to the
database without any sanitization, such as
`ON CONFLICT (coalesce(firstname, ""), coalesce(lastname, ""))`.
See the "Shared options" section at the module documentation for
remaining options.
## Examples
MyRepo.insert_all(Post, [[title: "My first post"], [title: "My second post"]])
MyRepo.insert_all(Post, [%{title: "My first post"}, %{title: "My second post"}])
## Upserts
`c:insert_all/3` provides upserts (update or inserts) via the `:on_conflict`
option. The `:on_conflict` option supports the following values:
* `:raise` - raises if there is a conflicting primary key or unique index
* `:nothing` - ignores the error in case of conflicts
* `:replace_all` - replace all values on the existing row by the new entry,
including values not sent explicitly by Ecto, such as database defaults.
This option requires a schema
* `:replace_all_except_primary_key` - same as above except primary keys are
not replaced. This option requires a schema
* `{:replace, fields}` - replace only specific columns. This option requires
conflict_target
* a keyword list of update instructions - such as the one given to
`c:update_all/3`, for example: `[set: [title: "new title"]]`
* an `Ecto.Query` that will act as an `UPDATE` statement, such as the
one given to `c:update_all/3`
Upserts map to "ON CONFLICT" on databases like Postgres and "ON DUPLICATE KEY"
on databases such as MySQL.
## Return values
By default, both Postgres and MySQL return the amount of entries
inserted on `c:insert_all/3`. However, when the `:on_conflict` option
is specified, Postgres will only return a row if it was affected
while MySQL returns at least the number of entries attempted.
For example, if `:on_conflict` is set to `:nothing`, Postgres will
return 0 if no new entry was added while MySQL will still return
the amount of entries attempted to be inserted, even if no entry
was added. Even worse, if `:on_conflict` is query, MySQL will return
the number of attempted entries plus the number of entries modified
by the UPDATE query.
"""
@callback insert_all(
schema_or_source :: binary | {binary, module} | module,
entries :: [map | [{atom, term | Ecto.Query.t}]],
opts :: Keyword.t()
) :: {integer, nil | [term]}
@doc """
Inserts a struct defined via `Ecto.Schema` or a changeset.
In case a struct is given, the struct is converted into a changeset
with all non-nil fields as part of the changeset.
In case a changeset is given, the changes in the changeset are
merged with the struct fields, and all of them are sent to the
database.
It returns `{:ok, struct}` if the struct has been successfully
inserted or `{:error, changeset}` if there was a validation
or a known constraint error.
## Options
* `:returning` - selects which fields to return. It accepts a list
of fields to be returned from the database. When `true`, returns
all fields. When `false`, no extra fields are returned. It will
always include all fields in `read_after_writes` as well as any
autogenerated id. Not all databases support this option and it
may not be available during upserts. See the "Upserts" section
for more information.
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This overrides the prefix set
in the query and any `@schema_prefix` set any schemas. Also, the
`@schema_prefix` for the parent record will override all default
`@schema_prefix`s set in any child schemas for associations.
* `:on_conflict` - It may be one of `:raise` (the default), `:nothing`,
`:replace_all`, `:replace_all_except_primary_key`, `{:replace, fields}`,
a keyword list of update instructions or an `Ecto.Query` query for updates.
See the "Upserts" section for more information.
* `:conflict_target` - A list of column names to verify for conflicts.
It is expected those columns to have unique indexes on them that may conflict.
If none is specified, the conflict target is left up to the database.
May also be `{:constraint, constraint_name_as_atom}` in databases
that support the "ON CONSTRAINT" expression, such as PostgreSQL.
* `:stale_error_field` - The field where stale errors will be added in
the returning changeset. This option can be used to avoid raising
`Ecto.StaleEntryError`.
* `:stale_error_message` - The message to add to the configured
`:stale_error_field` when stale errors happen, defaults to "is stale".
See the "Shared options" section at the module documentation for more options.
## Examples
A typical example is calling `MyRepo.insert/1` with a struct
and acting on the return value:
case MyRepo.insert %Post{title: "Ecto is great"} do
{:ok, struct} -> # Inserted with success
{:error, changeset} -> # Something went wrong
end
## Upserts
`c:insert/2` provides upserts (update or inserts) via the `:on_conflict`
option. The `:on_conflict` option supports the following values:
* `:raise` - raises if there is a conflicting primary key or unique index
* `:nothing` - ignores the error in case of conflicts
* `:replace_all` - replace all values on the existing row with the values
in the schema/changeset, including autogenerated fields such as `inserted_at`
and `updated_at`
* `:replace_all_except_primary_key` - same as above except primary keys are
not replaced
* `{:replace, fields}` - replace only specific columns. This option requires
conflict_target
* a keyword list of update instructions - such as the one given to
`c:update_all/3`, for example: `[set: [title: "new title"]]`
* an `Ecto.Query` that will act as an `UPDATE` statement, such as the
one given to `c:update_all/3`. If the struct cannot be found, `Ecto.StaleEntryError`
will be raised.
Upserts map to "ON CONFLICT" on databases like Postgres and "ON DUPLICATE KEY"
on databases such as MySQL.
As an example, imagine `:title` is marked as a unique column in
the database:
{:ok, inserted} = MyRepo.insert(%Post{title: "this is unique"})
Now we can insert with the same title but do nothing on conflicts:
{:ok, ignored} = MyRepo.insert(%Post{title: "this is unique"}, on_conflict: :nothing)
assert ignored.id == nil
Because we used `on_conflict: :nothing`, instead of getting an error,
we got `{:ok, struct}`. However the returned struct does not reflect
the data in the database. One possible mechanism to detect if an
insert or nothing happened in case of `on_conflict: :nothing` is by
checking the `id` field. `id` will be nil if the field is autogenerated
by the database and no insert happened.
For actual upserts, where an insert or update may happen, the situation
is slightly more complex, as the database does not actually inform us
if an insert or update happened. Let's insert a post with the same title
but use a query to update the body column in case of conflicts:
# In Postgres (it requires the conflict target for updates):
on_conflict = [set: [body: "updated"]]
{:ok, updated} = MyRepo.insert(%Post{title: "this is unique"},
on_conflict: on_conflict, conflict_target: :title)
# In MySQL (conflict target is not supported):
on_conflict = [set: [title: "updated"]]
{:ok, updated} = MyRepo.insert(%Post{id: inserted.id, title: "updated"},
on_conflict: on_conflict)
In the examples above, even though it returned `:ok`, we do not know
if we inserted new data or if we updated only the `:on_conflict` fields.
In case an update happened, the data in the struct most likely does
not match the data in the database. For example, autogenerated fields
such as `inserted_at` will point to now rather than the time the
struct was actually inserted.
If you need to guarantee the data in the returned struct mirrors the
database, you have three options:
* Use `on_conflict: :replace_all`, although that will replace all
fields in the database with the ones in the struct/changeset,
including autogenerated fields such as `insert_at` and `updated_at`:
MyRepo.insert(%Post{title: "this is unique"},
on_conflict: :replace_all, conflict_target: :title)
* Specify `read_after_writes: true` in your schema for choosing
fields that are read from the database after every operation.
Or pass `returning: true` to `insert` to read all fields back:
MyRepo.insert(%Post{title: "this is unique"}, returning: true,
on_conflict: on_conflict, conflict_target: :title)
* Alternatively, read the data again from the database in a separate
query. This option requires the primary key to be generated by the
database:
{:ok, updated} = MyRepo.insert(%Post{title: "this is unique"}, on_conflict: on_conflict)
Repo.get(Post, updated.id)
Because of the inability to know if the struct is up to date or not,
inserting a struct with associations and using the `:on_conflict` option
at the same time is not recommended, as Ecto will be unable to actually
track the proper status of the association.
"""
@callback insert(
struct_or_changeset :: Ecto.Schema.t() | Ecto.Changeset.t(),
opts :: Keyword.t()
) :: {:ok, Ecto.Schema.t()} | {:error, Ecto.Changeset.t()}
@doc """
Updates a changeset using its primary key.
A changeset is required as it is the only mechanism for
tracking dirty changes. Only the fields present in the `changes` part
of the changeset are sent to the database. Any other, in-memory
changes done to the schema are ignored.
If the struct has no primary key, `Ecto.NoPrimaryKeyFieldError`
will be raised.
If the struct cannot be found, `Ecto.StaleEntryError` will be raised.
It returns `{:ok, struct}` if the struct has been successfully
updated or `{:error, changeset}` if there was a validation
or a known constraint error.
## Options
* `:returning` - selects which fields to return. It accepts a list
of fields to be returned from the database. When `true`, returns
all fields. When `false`, no extra fields are returned. It will
always include all fields in `read_after_writes`. Not all
databases support this option.
* `:force` - By default, if there are no changes in the changeset,
`c:update/2` is a no-op. By setting this option to true, update
callbacks will always be executed, even if there are no changes
(including timestamps).
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This overrides the prefix set
in the query and any `@schema_prefix` set any schemas. Also, the
`@schema_prefix` for the parent record will override all default
`@schema_prefix`s set in any child schemas for associations.
* `:stale_error_field` - The field where stale errors will be added in
the returning changeset. This option can be used to avoid raising
`Ecto.StaleEntryError`.
* `:stale_error_message` - The message to add to the configured
`:stale_error_field` when stale errors happen, defaults to "is stale".
See the "Shared options" section at the module documentation for more options.
## Example
post = MyRepo.get!(Post, 42)
post = Ecto.Changeset.change post, title: "New title"
case MyRepo.update post do
{:ok, struct} -> # Updated with success
{:error, changeset} -> # Something went wrong
end
"""
@callback update(changeset :: Ecto.Changeset.t(), opts :: Keyword.t()) ::
{:ok, Ecto.Schema.t()} | {:error, Ecto.Changeset.t()}
@doc """
Inserts or updates a changeset depending on whether the struct is persisted
or not.
The distinction whether to insert or update will be made on the
`Ecto.Schema.Metadata` field `:state`. The `:state` is automatically set by
Ecto when loading or building a schema.
Please note that for this to work, you will have to load existing structs from
the database. So even if the struct exists, this won't work:
struct = %Post{id: "existing_id", ...}
MyRepo.insert_or_update changeset
# => {:error, changeset} # id already exists
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This overrides the prefix set
in the query and any `@schema_prefix` set any schemas. Also, the
`@schema_prefix` for the parent record will override all default
`@schema_prefix`s set in any child schemas for associations.
* `:stale_error_field` - The field where stale errors will be added in
the returning changeset. This option can be used to avoid raising
`Ecto.StaleEntryError`. Only applies to updates.
* `:stale_error_message` - The message to add to the configured
`:stale_error_field` when stale errors happen, defaults to "is stale".
Only applies to updates.
See the "Shared options" section at the module documentation for more options.
## Example
result =
case MyRepo.get(Post, id) do
nil -> %Post{id: id} # Post not found, we build one
post -> post # Post exists, let's use it
end
|> Post.changeset(changes)
|> MyRepo.insert_or_update
case result do
{:ok, struct} -> # Inserted or updated with success
{:error, changeset} -> # Something went wrong
end
"""
@callback insert_or_update(changeset :: Ecto.Changeset.t(), opts :: Keyword.t()) ::
{:ok, Ecto.Schema.t()} | {:error, Ecto.Changeset.t()}
@doc """
Deletes a struct using its primary key.
If the struct has no primary key, `Ecto.NoPrimaryKeyFieldError`
will be raised. If the struct has been removed from db prior to
call, `Ecto.StaleEntryError` will be raised.
It returns `{:ok, struct}` if the struct has been successfully
deleted or `{:error, changeset}` if there was a validation
or a known constraint error.
## Options
* `:prefix` - The prefix to run the query on (such as the schema path
in Postgres or the database in MySQL). This overrides the prefix set
in the query and any `@schema_prefix` set in the schema.
* `:stale_error_field` - The field where stale errors will be added in
the returning changeset. This option can be used to avoid raising
`Ecto.StaleEntryError`.
* `:stale_error_message` - The message to add to the configured
`:stale_error_field` when stale errors happen, defaults to "is stale".
See the "Shared options" section at the module documentation for more options.
## Example
post = MyRepo.get!(Post, 42)
case MyRepo.delete post do
{:ok, struct} -> # Deleted with success
{:error, changeset} -> # Something went wrong
end
"""
@callback delete(
struct_or_changeset :: Ecto.Schema.t() | Ecto.Changeset.t(),
opts :: Keyword.t()
) :: {:ok, Ecto.Schema.t()} | {:error, Ecto.Changeset.t()}
@doc """
Same as `c:insert/2` but returns the struct or raises if the changeset is invalid.
"""
@callback insert!(
struct_or_changeset :: Ecto.Schema.t() | Ecto.Changeset.t(),
opts :: Keyword.t()
) :: Ecto.Schema.t()
@doc """
Same as `c:update/2` but returns the struct or raises if the changeset is invalid.
"""
@callback update!(changeset :: Ecto.Changeset.t(), opts :: Keyword.t()) ::
Ecto.Schema.t()
@doc """
Same as `c:insert_or_update/2` but returns the struct or raises if the changeset
is invalid.
"""
@callback insert_or_update!(changeset :: Ecto.Changeset.t(), opts :: Keyword.t()) ::
Ecto.Schema.t()
@doc """
Same as `c:delete/2` but returns the struct or raises if the changeset is invalid.
"""
@callback delete!(
struct_or_changeset :: Ecto.Schema.t() | Ecto.Changeset.t(),
opts :: Keyword.t()
) :: Ecto.Schema.t()
## Ecto.Adapter.Transaction
@optional_callbacks transaction: 2, in_transaction?: 0, rollback: 1
@doc """
Runs the given function or `Ecto.Multi` inside a transaction.
## Use with function
`c:transaction/2` can be called with both a function of arity
zero or one. The arity zero function will just be executed as is,
while the arity one function will receive the repo of the transaction
as its first argument, similar to `Ecto.Multi.run`.
If an unhandled error occurs the transaction will be rolled back
and the error will bubble up from the transaction function.
If no error occurred the transaction will be committed when the
function returns. A transaction can be explicitly rolled back
by calling `c:rollback/1`, this will immediately leave the function
and return the value given to `rollback` as `{:error, value}`.
A successful transaction returns the value returned by the function
wrapped in a tuple as `{:ok, value}`.
If `c:transaction/2` is called inside another transaction, the function
is simply executed, without wrapping the new transaction call in any
way. If there is an error in the inner transaction and the error is
rescued, or the inner transaction is rolled back, the whole outer
transaction is marked as tainted, guaranteeing nothing will be committed.
## Use with Ecto.Multi
Besides functions transaction can be used with an Ecto.Multi struct.
Transaction will be started, all operations applied and in case of
success committed returning `{:ok, changes}`. In case of any errors
the transaction will be rolled back and
`{:error, failed_operation, failed_value, changes_so_far}` will be
returned.
You can read more about using transactions with `Ecto.Multi` as well as
see some examples in the `Ecto.Multi` documentation.
## Options
See the "Shared options" section at the module documentation for more options.
## Examples
import Ecto.Changeset, only: [change: 2]
MyRepo.transaction(fn ->
MyRepo.update!(change(alice, balance: alice.balance - 10))
MyRepo.update!(change(bob, balance: bob.balance + 10))
end)
# When passing a function of arity 1, it receives the repository itself
MyRepo.transaction(fn repo ->
repo.insert!(%Post{})
end)
# Roll back a transaction explicitly
MyRepo.transaction(fn ->
p = MyRepo.insert!(%Post{})
if not Editor.post_allowed?(p) do
MyRepo.rollback(:posting_not_allowed)
end
end)
# With Ecto.Multi
Ecto.Multi.new()
|> Ecto.Multi.insert(:post, %Post{})
|> MyRepo.transaction
"""
@callback transaction(fun_or_multi :: fun | Ecto.Multi.t(), opts :: Keyword.t()) ::
{:ok, any}
| {:error, any}
| {:error, Ecto.Multi.name(), any, %{Ecto.Multi.name() => any}}
@doc """
Returns true if the current process is inside a transaction.
If you are using the `Ecto.Adapters.SQL.Sandbox` in tests, note that even
though each test is inside a transaction, `in_transaction?/0` will only
return true inside transactions explicitly created with `transaction/2`. This
is done so the test environment mimics dev and prod.
If you are trying to debug transaction-related code while using
`Ecto.Adapters.SQL.Sandbox`, it may be more helpful to configure the database
to log all statements and consult those logs.
## Examples
MyRepo.in_transaction?
#=> false
MyRepo.transaction(fn ->
MyRepo.in_transaction? #=> true
end)
"""
@callback in_transaction?() :: boolean
@doc """
Rolls back the current transaction.
The transaction will return the value given as `{:error, value}`.
"""
@callback rollback(value :: any) :: no_return
end
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