-
Notifications
You must be signed in to change notification settings - Fork 1.4k
/
multi.ex
624 lines (491 loc) · 21.1 KB
/
multi.ex
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
defmodule Ecto.Multi do
@moduledoc """
`Ecto.Multi` is a data structure for grouping multiple Repo operations.
`Ecto.Multi` makes it possible to pack operations that should be
performed in a single database transaction and gives a way to introspect
the queued operations without actually performing them. Each operation
is given a name that is unique and will identify its result in case of
success or failure.
All operations will be executed in the order they were added.
The `Ecto.Multi` structure should be considered opaque. You can use
`%Ecto.Multi{}` to pattern match the type, but accessing fields or
directly modifying them is not advised.
`Ecto.Multi.to_list/1` returns a canonical representation of the
structure that can be used for introspection.
## Changesets
If multi contains operations that accept changesets (like `insert/4`,
`update/4` or `delete/4`) they will be checked before starting the
transaction. If any changeset has errors, the transaction won't even
be started and the error will be immediately returned.
Note: `insert/4`, `update/4`, `insert_or_update/4`, and `delete/4`
variants that accept a function are not performing such checks since
the functions are executed after the transaction has started.
## Run
Multi allows you to run arbitrary functions as part of your transaction
via `run/3` and `run/5`. This is especially useful when an operation
depends on the value of a previous operation. For this reason, the
function given as a callback to `run/3` and `run/5` will receive the repo
as the first argument, and all changes performed by the multi so far as a
map for the second argument.
The function given to `run` must return `{:ok, value}` or `{:error, value}`
as its result. Returning an error will abort any further operations
and make the whole multi fail.
## Example
Let's look at an example definition and usage. The use case we'll be
looking into is resetting a password. We need to update the account
with proper information, log the request and remove all current sessions:
defmodule PasswordManager do
alias Ecto.Multi
def reset(account, params) do
Multi.new
|> Multi.update(:account, Account.password_reset_changeset(account, params))
|> Multi.insert(:log, Log.password_reset_changeset(account, params))
|> Multi.delete_all(:sessions, Ecto.assoc(account, :sessions))
end
end
We can later execute it in the integration layer using Repo:
Repo.transaction(PasswordManager.reset(account, params))
By pattern matching on the result we can differentiate different conditions:
case result do
{:ok, %{account: account, log: log, sessions: sessions}} ->
# Operation was successful, we can access results (exactly the same
# we would get from running corresponding Repo functions) under keys
# we used for naming the operations.
{:error, failed_operation, failed_value, changes_so_far} ->
# One of the operations failed. We can access the operation's failure
# value (like changeset for operations on changesets) to prepare a
# proper response. We also get access to the results of any operations
# that succeeded before the indicated operation failed. However, any
# successful operations would have been rolled back.
end
We can also easily unit test our transaction without actually running it.
Since changesets can use in-memory-data, we can use an account that is
constructed in memory as well (without persisting it to the database):
test "dry run password reset" do
account = %Account{password: "letmein"}
multi = PasswordManager.reset(account, params)
assert [
{:account, {:update, account_changeset, []}},
{:log, {:insert, log_changeset, []}},
{:sessions, {:delete_all, query, []}}
] = Ecto.Multi.to_list(multi)
# We can introspect changesets and query to see if everything
# is as expected, for example:
assert account_changeset.valid?
assert log_changeset.valid?
assert inspect(query) == "#Ecto.Query<from a in Session>"
end
The name of each operation does not have to be an atom. This can be particularly
useful when you wish to update a collection of changesets at once, and track their
errors individually:
accounts = [%Account{id: 1}, %Account{id: 2}]
Enum.reduce(accounts, Multi.new(), fn account, multi ->
Multi.update(
multi,
{:account, account.id},
Account.password_reset_changeset(account, params)
)
end)
"""
alias __MODULE__
alias Ecto.Changeset
defstruct operations: [], names: MapSet.new
@type changes :: map
@type run :: ((Ecto.Repo.t, changes) -> {:ok | :error, any}) | {module, atom, [any]}
@type fun(result) :: (changes -> result)
@type merge :: (changes -> t) | {module, atom, [any]}
@typep schema_or_source :: binary | {binary | nil, binary} | atom
@typep operation :: {:changeset, Changeset.t, Keyword.t} |
{:run, run} |
{:merge, merge} |
{:update_all, Ecto.Query.t, Keyword.t} |
{:delete_all, Ecto.Query.t, Keyword.t} |
{:insert_all, schema_or_source, [map | Keyword.t], Keyword.t}
@typep operations :: [{name, operation}]
@typep names :: MapSet.t
@type name :: any
@type t :: %__MODULE__{operations: operations, names: names}
@doc """
Returns an empty `Ecto.Multi` struct.
## Example
iex> Ecto.Multi.new |> Ecto.Multi.to_list
[]
"""
@spec new :: t
def new do
%Multi{}
end
@doc """
Appends the second multi to the first one.
All names must be unique between both structures.
## Example
iex> lhs = Ecto.Multi.new |> Ecto.Multi.run(:left, fn _, changes -> {:ok, changes} end)
iex> rhs = Ecto.Multi.new |> Ecto.Multi.run(:right, fn _, changes -> {:error, changes} end)
iex> Ecto.Multi.append(lhs, rhs) |> Ecto.Multi.to_list |> Keyword.keys
[:left, :right]
"""
@spec append(t, t) :: t
def append(lhs, rhs) do
merge_structs(lhs, rhs, &(&2 ++ &1))
end
@doc """
Prepends the second multi to the first one.
All names must be unique between both structures.
## Example
iex> lhs = Ecto.Multi.new |> Ecto.Multi.run(:left, fn _, changes -> {:ok, changes} end)
iex> rhs = Ecto.Multi.new |> Ecto.Multi.run(:right, fn _, changes -> {:error, changes} end)
iex> Ecto.Multi.prepend(lhs, rhs) |> Ecto.Multi.to_list |> Keyword.keys
[:right, :left]
"""
@spec prepend(t, t) :: t
def prepend(lhs, rhs) do
merge_structs(lhs, rhs, &(&1 ++ &2))
end
defp merge_structs(%Multi{} = lhs, %Multi{} = rhs, joiner) do
%{names: lhs_names, operations: lhs_ops} = lhs
%{names: rhs_names, operations: rhs_ops} = rhs
case MapSet.intersection(lhs_names, rhs_names) |> MapSet.to_list do
[] ->
%Multi{names: MapSet.union(lhs_names, rhs_names),
operations: joiner.(lhs_ops, rhs_ops)}
common ->
raise ArgumentError, """
error when merging the following Ecto.Multi structs:
#{inspect lhs}
#{inspect rhs}
both declared operations: #{inspect common}
"""
end
end
@doc """
Merges a multi returned dynamically by an anonymous function.
This function is useful when the multi to be merged requires information
from the original multi. Hence the second argument is an anonymous function
that receives the multi changes so far. The anonymous function must return
another multi.
If you would prefer to simply merge two multis together, see `append/2` or
`prepend/2`.
Duplicated operations are not allowed.
## Example
Ecto.Multi.merge(multi, fn %{post: post} ->
Ecto.Multi.new()
|> Ecto.Multi.insert(:comment, Ecto.build_assoc(post, :comments))
end)
"""
@spec merge(t, (changes -> t)) :: t
def merge(%Multi{} = multi, merge) when is_function(merge, 1) do
Map.update!(multi, :operations, &[{:merge, {:merge, merge}} | &1])
end
@doc """
Merges a multi returned dynamically by calling `module` and `function` with `args`.
Similar to `merge/2`, but allows to pass module name, function and arguments.
The function should return an `Ecto.Multi`, and receives changes so far
as the first argument (prepended to those passed in the call to the function).
Duplicated operations are not allowed.
"""
@spec merge(t, module, function, args) :: t when function: atom, args: [any]
def merge(%Multi{} = multi, mod, fun, args)
when is_atom(mod) and is_atom(fun) and is_list(args) do
Map.update!(multi, :operations, &[{:merge, {:merge, {mod, fun, args}}} | &1])
end
@doc """
Adds an insert operation to the multi.
Accepts the same arguments and options as `c:Ecto.Repo.insert/2` does.
## Example
Ecto.Multi.new()
|> Ecto.Multi.insert(:insert, %Post{title: "first"})
|> MyApp.Repo.transaction()
Ecto.Multi.new()
|> Ecto.Multi.insert(:post, %Post{title: "first"})
|> Ecto.Multi.insert(:comment, fn %{post: post} ->
Ecto.build_assoc(post, :comments)
end)
|> MyApp.Repo.transaction()
"""
@spec insert(t, name, Changeset.t | Ecto.Schema.t | fun(Changeset.t | Ecto.Schema.t), Keyword.t) :: t
def insert(multi, name, changeset_or_struct_or_fun, opts \\ [])
def insert(multi, name, %Changeset{} = changeset, opts) do
add_changeset(multi, :insert, name, changeset, opts)
end
def insert(multi, name, %_{} = struct, opts) do
insert(multi, name, Changeset.change(struct), opts)
end
def insert(multi, name, fun, opts) when is_function(fun, 1) do
run(multi, name, operation_fun(:insert, opts, fun))
end
@doc """
Adds an update operation to the multi.
Accepts the same arguments and options as `c:Ecto.Repo.update/2` does.
## Example
post = MyApp.Repo.get!(Post, 1)
changeset = Ecto.Changeset.change(post, title: "New title")
Ecto.Multi.new()
|> Ecto.Multi.update(:update, changeset)
|> MyApp.Repo.transaction()
Ecto.Multi.new()
|> Ecto.Multi.insert(:post, %Post{title: "first"})
|> Ecto.Multi.update(:fun, fn %{post: post} ->
Ecto.Changeset.change(post, title: "New title")
end)
|> MyApp.Repo.transaction()
"""
@spec update(t, name, Changeset.t | fun(Changeset.t), Keyword.t) :: t
def update(multi, name, changeset_or_fun, opts \\ [])
def update(multi, name, %Changeset{} = changeset, opts) do
add_changeset(multi, :update, name, changeset, opts)
end
def update(multi, name, fun, opts) when is_function(fun, 1) do
run(multi, name, operation_fun(:update, opts, fun))
end
@doc """
Inserts or updates a changeset depending on whether the changeset was persisted or not.
Accepts the same arguments and options as `c:Ecto.Repo.insert_or_update/2` does.
## Example
changeset = Post.changeset(%Post{}, %{title: "New title"})
Ecto.Multi.new()
|> Ecto.Multi.insert_or_update(:insert_or_update, changeset)
|> MyApp.Repo.transaction()
Ecto.Multi.new()
|> Ecto.Multi.run(:post, fn _repo, _changes ->
{:ok, MyApp.Repo.get(Post, 1) || %Post{}}
end)
|> Ecto.Multi.insert_or_update(:update, fn %{post: post} ->
Ecto.Changeset.change(post, title: "New title")
end)
|> MyApp.Repo.transaction()
"""
@spec insert_or_update(t, name, Changeset.t | fun(Changeset.t), Keyword.t) :: t
def insert_or_update(multi, name, changeset, opts \\ [])
def insert_or_update(multi, name, %Changeset{data: %{__meta__: %{state: :loaded}}} = changeset, opts) do
add_changeset(multi, :update, name, changeset, opts)
end
def insert_or_update(multi, name, %Changeset{} = changeset, opts) do
add_changeset(multi, :insert, name, changeset, opts)
end
def insert_or_update(multi, name, fun, opts) when is_function(fun, 1) do
run(multi, name, operation_fun(:insert_or_update, opts, fun))
end
@doc """
Adds a delete operation to the multi.
Accepts the same arguments and options as `c:Ecto.Repo.delete/2` does.
## Example
post = MyApp.Repo.get!(Post, 1)
Ecto.Multi.new()
|> Ecto.Multi.delete(:delete, post)
|> MyApp.Repo.transaction()
Ecto.Multi.new()
|> Ecto.Multi.run(:post, fn _repo, _changes ->
case MyApp.Repo.get(Post, 1) do
nil -> {:error, :not_found}
post -> {:ok, post}
end
end)
|> Ecto.Multi.delete(:delete, fn %{post: post} ->
# Others validations
post
end)
|> MyApp.Repo.transaction()
"""
@spec delete(t, name, Changeset.t | Ecto.Schema.t | fun(Changeset.t | Ecto.Schema.t), Keyword.t) :: t
def delete(multi, name, changeset_or_struct_fun, opts \\ [])
def delete(multi, name, %Changeset{} = changeset, opts) do
add_changeset(multi, :delete, name, changeset, opts)
end
def delete(multi, name, %_{} = struct, opts) do
delete(multi, name, Changeset.change(struct), opts)
end
def delete(multi, name, fun, opts) when is_function(fun, 1) do
run(multi, name, operation_fun(:delete, opts, fun))
end
defp add_changeset(multi, action, name, changeset, opts) when is_list(opts) do
add_operation(multi, name, {:changeset, put_action(changeset, action), opts})
end
defp put_action(%{action: nil} = changeset, action) do
%{changeset | action: action}
end
defp put_action(%{action: action} = changeset, action) do
changeset
end
defp put_action(%{action: original}, action) do
raise ArgumentError, "you provided a changeset with an action already set " <>
"to #{inspect original} when trying to #{action} it"
end
@doc """
Causes the multi to fail with the given value.
Running the multi in a transaction will execute
no previous steps and returns the value of the first
error added.
"""
@spec error(t, name, error :: term) :: t
def error(multi, name, value) do
add_operation(multi, name, {:error, value})
end
@doc """
Adds a function to run as part of the multi.
The function should return either `{:ok, value}` or `{:error, value}`,
and receives the repo as the first argument, and the changes so far
as the second argument.
## Example
Ecto.Multi.run(multi, :write, fn _repo, %{image: image} ->
with :ok <- File.write(image.name, image.contents) do
{:ok, nil}
end
end)
"""
@spec run(t, name, run) :: t
def run(multi, name, run) when is_function(run, 2) do
add_operation(multi, name, {:run, run})
end
@doc """
Adds a function to run as part of the multi.
Similar to `run/3`, but allows to pass module name, function and arguments.
The function should return either `{:ok, value}` or `{:error, value}`, and
receives the repo as the first argument, and the changes so far as the
second argument (prepended to those passed in the call to the function).
"""
@spec run(t, name, module, function, args) :: t when function: atom, args: [any]
def run(multi, name, mod, fun, args)
when is_atom(mod) and is_atom(fun) and is_list(args) do
add_operation(multi, name, {:run, {mod, fun, args}})
end
@doc """
Adds an insert_all operation to the multi.
Accepts the same arguments and options as `c:Ecto.Repo.insert_all/3` does.
## Example
posts = [%{title: "My first post"}, %{title: "My second post"}]
Ecto.Multi.new()
|> Ecto.Multi.insert_all(:insert_all, Post, posts)
|> MyApp.Repo.transaction()
"""
@spec insert_all(t, name, schema_or_source, [map | Keyword.t], Keyword.t) :: t
def insert_all(multi, name, schema_or_source, entries, opts \\ []) when is_list(opts) do
add_operation(multi, name, {:insert_all, schema_or_source, entries, opts})
end
@doc """
Adds an update_all operation to the multi.
Accepts the same arguments and options as `c:Ecto.Repo.update_all/3` does.
## Example
Ecto.Multi.new()
|> Ecto.Multi.update_all(:update_all, Post, set: [title: "New title"])
|> MyApp.Repo.transaction()
"""
@spec update_all(t, name, Ecto.Queryable.t, Keyword.t, Keyword.t) :: t
def update_all(multi, name, queryable, updates, opts \\ []) when is_list(opts) do
query = Ecto.Queryable.to_query(queryable)
add_operation(multi, name, {:update_all, query, updates, opts})
end
@doc """
Adds a delete_all operation to the multi.
Accepts the same arguments and options as `c:Ecto.Repo.delete_all/2` does.
## Example
queryable = from(p in Post, where: p.id < 5)
Ecto.Multi.new()
|> Ecto.Multi.delete_all(:delete_all, queryable)
|> MyApp.Repo.transaction()
"""
@spec delete_all(t, name, Ecto.Queryable.t, Keyword.t) :: t
def delete_all(multi, name, queryable, opts \\ []) when is_list(opts) do
query = Ecto.Queryable.to_query(queryable)
add_operation(multi, name, {:delete_all, query, opts})
end
defp add_operation(%Multi{} = multi, name, operation) do
%{operations: operations, names: names} = multi
if MapSet.member?(names, name) do
raise "#{inspect name} is already a member of the Ecto.Multi: \n#{inspect multi}"
else
%{multi | operations: [{name, operation} | operations],
names: MapSet.put(names, name)}
end
end
@doc """
Returns the list of operations stored in `multi`.
Always use this function when you need to access the operations you
have defined in `Ecto.Multi`. Inspecting the `Ecto.Multi` struct internals
directly is discouraged.
"""
@spec to_list(t) :: [{name, term}]
def to_list(%Multi{operations: operations}) do
operations
|> Enum.reverse
|> Enum.map(&format_operation/1)
end
defp format_operation({name, {:changeset, changeset, opts}}),
do: {name, {changeset.action, changeset, opts}}
defp format_operation(other),
do: other
@doc false
@spec __apply__(t, Ecto.Repo.t, fun, (term -> no_return)) :: {:ok, term} | {:error, term}
def __apply__(%Multi{} = multi, repo, wrap, return) do
operations = Enum.reverse(multi.operations)
with {:ok, operations} <- check_operations_valid(operations) do
apply_operations(operations, multi.names, repo, wrap, return)
end
end
defp check_operations_valid(operations) do
Enum.find_value(operations, &invalid_operation/1) || {:ok, operations}
end
defp invalid_operation({name, {:changeset, %{valid?: false} = changeset, _}}),
do: {:error, {name, changeset, %{}}}
defp invalid_operation({name, {:error, value}}),
do: {:error, {name, value, %{}}}
defp invalid_operation(_operation),
do: nil
defp apply_operations([], _names, _repo, _wrap, _return), do: {:ok, %{}}
defp apply_operations(operations, names, repo, wrap, return) do
wrap.(fn ->
operations
|> Enum.reduce({%{}, names}, &apply_operation(&1, repo, wrap, return, &2))
|> elem(0)
end)
end
defp apply_operation({_, {:merge, merge}}, repo, wrap, return, {acc, names}) do
case __apply__(apply_merge_fun(merge, acc), repo, wrap, return) do
{:ok, value} ->
merge_results(acc, value, names)
{:error, {name, value, nested_acc}} ->
{acc, _names} = merge_results(acc, nested_acc, names)
return.({name, value, acc})
end
end
defp apply_operation({name, operation}, repo, wrap, return, {acc, names}) do
case apply_operation(operation, acc, {wrap, return}, repo) do
{:ok, value} ->
{Map.put(acc, name, value), names}
{:error, value} ->
return.({name, value, acc})
other ->
raise "expected Ecto.Multi callback named `#{inspect(name)}` to return either {:ok, value} or {:error, value}, got: #{inspect(other)}"
end
end
defp apply_operation({:changeset, changeset, opts}, _acc, _apply_args, repo),
do: apply(repo, changeset.action, [changeset, opts])
defp apply_operation({:run, run}, acc, _apply_args, repo),
do: apply_run_fun(run, repo, acc)
defp apply_operation({:error, value}, _acc, _apply_args, _repo),
do: {:error, value}
defp apply_operation({:insert_all, source, entries, opts}, _acc, _apply_args, repo),
do: {:ok, repo.insert_all(source, entries, opts)}
defp apply_operation({:update_all, query, updates, opts}, _acc, _apply_args, repo),
do: {:ok, repo.update_all(query, updates, opts)}
defp apply_operation({:delete_all, query, opts}, _acc, _apply_args, repo),
do: {:ok, repo.delete_all(query, opts)}
defp apply_merge_fun({mod, fun, args}, acc), do: apply(mod, fun, [acc | args])
defp apply_merge_fun(fun, acc), do: apply(fun, [acc])
defp apply_run_fun({mod, fun, args}, repo, acc), do: apply(mod, fun, [repo, acc | args])
defp apply_run_fun(fun, repo, acc), do: apply(fun, [repo, acc])
defp merge_results(changes, new_changes, names) do
new_names = new_changes |> Map.keys |> MapSet.new
case MapSet.intersection(names, new_names) |> MapSet.to_list do
[] ->
{Map.merge(changes, new_changes), MapSet.union(names, new_names)}
common ->
raise "cannot merge multi, the following operations were found in " <>
"both Ecto.Multi: #{inspect common}"
end
end
defp operation_fun(operation, opts, fun) do
fn repo, changes ->
apply(repo, operation, [fun.(changes), opts])
end
end
end