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Mito

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Mito is yet another object relational mapper, and it aims to be a successor of Integral.

  • Supports MySQL, PostgreSQL and SQLite3
  • Adds id (serial/uuid primary key), created_at and updated_at by default like Ruby's ActiveRecord
  • Migrations
  • DB schema versioning

Warning

This software is still ALPHA quality. The APIs likely change.

This software should work fine with MySQL, PostgreSQL and SQLite3 on SBCL/Clozure CL.

Usage

(mito:connect-toplevel :mysql :database-name "myapp" :username "fukamachi" :password "c0mon-1isp")
;=> #<DBD.MYSQL:<DBD-MYSQL-CONNECTION> {100691BFF3}>

(mito:deftable user ()
  ((name :col-type (:varchar 64))
   (email :col-type (or (:varchar 128) :null))))
;=> #<MITO.DAO.TABLE:DAO-TABLE-CLASS COMMON-LISP-USER::USER>

(mito:table-definition 'user)
;=> (#<SXQL-STATEMENT: CREATE TABLE user (id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, name VARCHAR(64) NOT NULL, email VARCHAR(128))>)

(mito:deftable tweet ()
  ((status :col-type :text)
   (user :col-type user)))
;=> #<MITO.DAO.TABLE:DAO-TABLE-CLASS COMMON-LISP-USER::TWEET>

(mito:table-definition 'tweet)
;=> (#<SXQL-STATEMENT: CREATE TABLE tweet (id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, status TEXT NOT NULL, user_id BIGINT UNSIGNED NOT NULL, created_at TIMESTAMP, updated_at TIMESTAMP)>)

Connecting to DB

Mito provides the functions connect-toplevel and disconnect-toplevel to establish and sever a connection to RDBMS.

connect-toplevel takes the same arguments as dbi:connect: typically the driver-type, the database name to connect, user name and password.

(mito:connect-toplevel :mysql :database-name "myapp" :username "fukamachi" :password "c0mon-1isp")

connect-toplevel sets *connection* to a new connection and returns it.

To use a connection lexically, just bind it:

(let ((mito:*connection* (dbi:connect :sqlite3 :database-name #P"/tmp/myapp.db")))
  (unwind-protect (progn ...)
    ;; Ensure that the connection is closed.
    (dbi:disconnect mito:*connection*)))

In most cases dbi:connect-cached is a better option, since it reuses a connection for multiple threads.

(let ((mito:*connection* (dbi:connect-cached :sqlite3 :database-name #P"/tmp/myapp.db")))
  (unwind-protect (progn ...)
    ;; Ensure that the connection is closed.
    ))

Use connection-database-name to get the name of the current connection, or of one named via parameter.

deftable macro

As Mito's dao table class is defined as a CLOS metaclass, a table class can be defined like this:

(defclass user ()
  ((name :col-type (:varchar 64)
         :accessor user-name)
   (email :col-type (or (:varchar 128) :null)
          :accessor user-email))
  (:metaclass mito:dao-table-class))

deftable's syntax is the same as that of cl:defclass. However, the definition is a little bit redundant.

mito:deftable is a thin macro, to allow definion of a table class with less typing.

For example, the above example can be rewritten, using deftable as follows.

(mito:deftable user ()
  ((name :col-type (:varchar 64))
   (email :col-type (or (:varchar 128) :null))))

It adds :metaclass mito:dao-table-class, and adds default accessors that start with <class-name>- by default, like defstruct does.

The prefix for accessors can be changed with the :conc-name class option:

(mito:deftable user ()
  ((name :col-type (:varchar 64))
   (email :col-type (or (:varchar 128) :null)))
  (:conc-name my-))

(my-name (make-instance 'user :name "fukamachi"))
;=> "fukamachi"

If :conc-name is NIL, default accessors will NOT be defined.

Class Definitions

In Mito, a class corresponding to a database table is defined by specifying (:metaclass mito:dao-table-class).

(defclass user ()
  ((name :col-type (:varchar 64)
         :accessor user-name)
   (email :col-type (or (:varchar 128) :null)
          :accessor user-email))
  (:metaclass mito:dao-table-class))

The above defines a Common Lisp normal class, except that it allows additional options.

(defclass {class-name} ()
  ({column-definition}*)
  (:metaclass mito:dao-table-class)
  [[class-option]])

column-definition ::= (slot-name [[column-option]])
column-option ::= {:col-type col-type} |
                  {:primary-key boolean} |
                  {:inflate inflation-function} |
                  {:deflate deflation-function} |
                  {:references {class-name | (class-name slot-name)}} |
                  {:ghost boolean}
col-type ::= { keyword |
              (keyword . args) |
              (or keyword :null) |
              (or :null keyword) }
class-option ::= {:primary-key symbol*} |
                 {:unique-keys {symbol | (symbol*)}*} |
                 {:keys {symbol | (symbol*)}*} |
                 {:table-name table-name} |
                 {:auto-pk auto-pk-mixin-class-name} |
                 {:record-timestamps boolean} |
                 {:conc-name conc-name}
auto-pk-mixin-class-name ::= {:serial | :uuid}
conc-name ::= {null | string-designator}

Note: the class automatically adds some slots -- a primary key named id if there is no primary key, created_at and updated_at for recording timestamps. To disable these behaviors, specify :auto-pk nil or :record-timestamps nil to defclass forms.

(mito.class:table-column-slots (find-class 'user))
;=> (#<MITO.DAO.COLUMN:DAO-TABLE-COLUMN-CLASS MITO.DAO.MIXIN::ID>
;    #<MITO.DAO.COLUMN:DAO-TABLE-COLUMN-CLASS COMMON-LISP-USER::NAME>
;    #<MITO.DAO.COLUMN:DAO-TABLE-COLUMN-CLASS COMMON-LISP-USER::EMAIL>
;    #<MITO.DAO.COLUMN:DAO-TABLE-COLUMN-CLASS MITO.DAO.MIXIN::CREATED-AT>
;    #<MITO.DAO.COLUMN:DAO-TABLE-COLUMN-CLASS MITO.DAO.MIXIN::UPDATED-AT>)

This class inherits mito:dao-class implicitly.

(find-class 'user)
;=> #<MITO.DAO.TABLE:DAO-TABLE-CLASS COMMON-LISP-USER::USER>

(c2mop:class-direct-superclasses *)
;=> (#<STANDARD-CLASS MITO.DAO.TABLE:DAO-CLASS>)

This may be useful to define methods that can be applied for many or all table classes.

:col-type Options

The following are valid keywords for :col-type in the deftable definition above.

:serial
:bigserial
:timestamptz
:integer
:bytea
:timestamp
:bigint
:unsigned
:int
:binary
:datetime

Besides the above keywords, there are other keywords that are valid, however they are dependent on the RDS and its version.

An example of this is that :json and :jsonb work for PostgreSQL but don't work on an old version of MySQL which doesn't support those types.

A complete list of valid :col-type options is dependent on the database system. Here's a link for the current Data Types for:

The symbols are not defined directly in the system, rather they are the symbol equivalent of the string which is the name for the data type. Therefore, for any data type name, just preprend a colon to the name :data-type in order to use it as a col-type.

Generating Table Definitions

(mito:table-definition 'user)
;=> (#<SXQL-STATEMENT: CREATE TABLE user (id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, name VARCHAR(64) NOT NULL, email VARCHAR(128), created_at TIMESTAMP, updated_at TIMESTAMP)>)

(sxql:yield *)
;=> "CREATE TABLE user (id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, name VARCHAR(64) NOT NULL, email VARCHAR(128), created_at TIMESTAMP, updated_at TIMESTAMP)"
;   NIL

Creating DB tables

(mapc #'mito:execute-sql (mito:table-definition 'user))

(mito:ensure-table-exists 'user)

CRUD

(defvar me
  (make-instance 'user :name "Eitaro Fukamachi" :email "e.arrows@gmail.com"))
;=> USER

(mito:insert-dao me)
;-> ;; INSERT INTO `user` (`name`, `email`, `created_at`, `updated_at`) VALUES (?, ?, ?, ?) ("Eitaro Fukamachi", "e.arrows@gmail.com", "2016-02-04T19:55:16.365543Z", "2016-02-04T19:55:16.365543Z") [0 rows] | MITO.DAO:INSERT-DAO
;=> #<USER {10053C4453}>

;; Same as above
(mito:create-dao 'user :name "Eitaro Fukamachi" :email "e.arrows@gmail.com")

;; Getting the primary key value
(mito:object-id me)
;=> 1

;; Retrieving from the DB
(mito:find-dao 'user :id 1)
;-> ;; SELECT * FROM `user` WHERE (`id` = ?) LIMIT 1 (1) [1 row] | MITO.DB:RETRIEVE-BY-SQL
;=> #<USER {10077C6073}>

(mito:retrieve-dao 'user)
;=> (#<USER {10077C6073}>)

;; Updating
(setf (slot-value me 'name) "nitro_idiot")
;=> "nitro_idiot"

(mito:save-dao me)
;-> ;; UPDATE `user` SET `id` = ?, `name` = ?, `email` = ?, `created_at` = ?, `updated_at` = ? WHERE (`id` = ?) (2, "nitro_idiot", "e.arrows@gmail.com", "2016-02-04T19:56:11.408927Z", "2016-02-04T19:56:19.006020Z", 2) [0 rows] | MITO.DAO:UPDATE-DAO

;; Deleting
(mito:delete-dao me)
;-> ;; DELETE FROM `user` WHERE (`id` = ?) (1) [0 rows] | MITO.DAO:DELETE-DAO
(mito:delete-by-values 'user :id 1)
;-> ;; DELETE FROM `user` WHERE (`id` = ?) (1) [0 rows] | MITO.DAO:DELETE-DAO

;; Counting
(mito:count-dao 'user)
;-> 1

Use select-dao to build custom queries with sxql (examples below).

Relationship

To define a relationship, use :references on the slot:

(mito:deftable user ()
  ((id :col-type (:varchar 36)
       :primary-key t)
   (name :col-type (:varchar 64))
   (email :col-type (or (:varchar 128) :null))))

(mito:deftable tweet ()
  ((status :col-type :text)
   ;; This slot refers to USER class
   (user-id :references (user id))))

;; The :col-type of USER-ID column is retrieved from the foreign class.
(mito:table-definition (find-class 'tweet))
;=> (#<SXQL-STATEMENT: CREATE TABLE tweet (
;       id BIGSERIAL NOT NULL PRIMARY KEY,
;       status TEXT NOT NULL,
;       user_id VARCHAR(36) NOT NULL,
;       created_at TIMESTAMPTZ,
;       updated_at TIMESTAMPTZ
;   )>)

You can also specify another foreign class at :col-type to define a relationship:

(mito:deftable tweet ()
  ((status :col-type :text)
   ;; This slot refers to USER class
   (user :col-type user)))

(mito:table-definition (find-class 'tweet))
;=> (#<SXQL-STATEMENT: CREATE TABLE tweet (
;        id BIGSERIAL NOT NULL PRIMARY KEY,
;        status TEXT NOT NULL,
;        user_id VARCHAR(36) NOT NULL,
;        created_at TIMESTAMP,
;        updated_at TIMESTAMP
;    )>)

;; You can specify :USER arg, instead of :USER-ID.
(defvar *user* (mito:create-dao 'user :name "Eitaro Fukamachi"))
(mito:create-dao 'tweet :user *user*)

(mito:find-dao 'tweet :user *user*)

The latter example allows you to create/retrieve TWEET by a USER object, not a USER-ID.

Mito doesn't add foreign key constraints for referring tables, since I'm not sure it's still handful while using with ORMs.

Inflation/Deflation

Inflation/Deflation is a function to convert values between Mito and RDBMS.

(mito:deftable user-report ()
  ((title :col-type (:varchar 100))
   (body :col-type :text
         :initform "")
   (reported-at :col-type :timestamp
                :initform (local-time:now)
                :inflate #'local-time:universal-to-timestamp
                :deflate #'local-time:timestamp-to-universal))
  (:conc-name report-))

Eager loading

One of the pains in the neck to use ORMs is the "N+1 query" problem.

;; BAD EXAMPLE

(use-package '(:mito :sxql))

(defvar *tweets-contain-japan*
  (select-dao 'tweet
    (where (:like :status "%Japan%"))))

;; Getting names of tweeted users.
(mapcar (lambda (tweet)
          (user-name (tweet-user tweet)))
        *tweets-contain-japan*)

This example sends a query to retrieve a user, like "SELECT * FROM user WHERE id = ?" for each iteration.

To prevent this performance issue, add includes to the above query, which sends only a single WHERE IN query instead of N queries:

;; GOOD EXAMPLE with eager loading

(use-package '(:mito :sxql))

(defvar *tweets-contain-japan*
  (select-dao 'tweet
    (includes 'user)
    (where (:like :status "%Japan%"))))
;-> ;; SELECT * FROM `tweet` WHERE (`status` LIKE ?) ("%Japan%") [3 row] | MITO.DB:RETRIEVE-BY-SQL
;-> ;; SELECT * FROM `user` WHERE (`id` IN (?, ?, ?)) (1, 3, 12) [3 row] | MITO.DB:RETRIEVE-BY-SQL
;=> (#<TWEET {1003513EC3}> #<TWEET {1007BABEF3}> #<TWEET {1007BB9D63}>)

;; No additional SQLs will be executed.
(tweet-user (first *))
;=> #<USER {100361E813}>

Migrations

(ensure-table-exists 'user)
;-> ;; CREATE TABLE IF NOT EXISTS "user" (
;       "id" BIGSERIAL NOT NULL PRIMARY KEY,
;       "name" VARCHAR(64) NOT NULL,
;       "email" VARCHAR(128),
;       "created_at" TIMESTAMP,
;       "updated_at" TIMESTAMP
;   ) () [0 rows] | MITO.DAO:ENSURE-TABLE-EXISTS

;; No changes
(mito:migration-expressions 'user)
;=> NIL

(mito:deftable user ()
  ((name :col-type (:varchar 64))
   (email :col-type (:varchar 128)))
  (:unique-keys email))

(mito:migration-expressions 'user)
;=> (#<SXQL-STATEMENT: ALTER TABLE user ALTER COLUMN email TYPE character varying(128), ALTER COLUMN email SET NOT NULL>
;    #<SXQL-STATEMENT: CREATE UNIQUE INDEX unique_user_email ON user (email)>)

(mito:migrate-table 'user)
;-> ;; ALTER TABLE "user" ALTER COLUMN "email" TYPE character varying(128), ALTER COLUMN "email" SET NOT NULL () [0 rows] | MITO.MIGRATION.TABLE:MIGRATE-TABLE
;   ;; CREATE UNIQUE INDEX "unique_user_email" ON "user" ("email") () [0 rows] | MITO.MIGRATION.TABLE:MIGRATE-TABLE
;-> (#<SXQL-STATEMENT: ALTER TABLE user ALTER COLUMN email TYPE character varying(128), ALTER COLUMN email SET NOT NULL>
;    #<SXQL-STATEMENT: CREATE UNIQUE INDEX unique_user_email ON user (email)>)

SQLite3 migration creates temporary tables with pre-migration data. To delete them after migration is complete set mito:*migration-keep-temp-tables* to nil. It has no effect on other drivers.

Auto migrations

If mito:*auto-migration-mode* is set to t, and you are connected to a database, Mito will run migrations after each change to model definitions.

Schema versioning

$ ros install mito
$ mito
Usage: mito command [option...]

Commands:
    generate-migrations
    migrate
    migration-status

Options:
    -t, --type DRIVER-TYPE          DBI driver type (one of "mysql", "postgres" or "sqlite3")
    -d, --database DATABASE-NAME    Database name to use
    -u, --username USERNAME         Username for RDBMS
    -p, --password PASSWORD         Password for RDBMS
    -s, --system SYSTEM             ASDF system to load (several -s's allowed)
    -D, --directory DIRECTORY       Directory path to keep migration SQL files (default: "/Users/nitro_idiot/Programs/lib/mito/db/")
    --dry-run                       List SQL expressions to migrate
    -f, --force                     Create a new empty migration file even when it's unnecessary.

Example

mito --database postgres --username fukamachi --pasword c0mmon-l1sp

Inheritance and Mixin

A subclass of DAO-CLASS is allowed to be inherited. This may be useful when you need classes that have similar columns:

(mito:deftable user ()
  ((name :col-type (:varchar 64))
   (email :col-type (:varchar 128)))
  (:unique-keys email))

(mito:deftable temporary-user (user)
  ((registered-at :col-type :timestamp)))

(mito:table-definition 'temporary-user)
;=> (#<SXQL-STATEMENT: CREATE TABLE temporary_user (
;        id BIGSERIAL NOT NULL PRIMARY KEY,
;        name VARCHAR(64) NOT NULL,
;        email VARCHAR(128) NOT NULL,
;        registered_at TIMESTAMP NOT NULL,
;        created_at TIMESTAMP,
;        updated_at TIMESTAMP,
;        UNIQUE (email)
;    )>)

If you need a 'template' for tables, not related to any specific database table, you can use DAO-TABLE-MIXIN:

(defclass has-email ()
  ((email :col-type (:varchar 128)
          :accessor object-email))
  (:metaclass mito:dao-table-mixin)
  (:unique-keys email))
;=> #<MITO.DAO.MIXIN:DAO-TABLE-MIXIN COMMON-LISP-USER::HAS-EMAIL>

(mito:deftable user (has-email)
  ((name :col-type (:varchar 64))))
;=> #<MITO.DAO.TABLE:DAO-TABLE-CLASS COMMON-LISP-USER::USER>

(mito:table-definition 'user)
;=> (#<SXQL-STATEMENT: CREATE TABLE user (
;       id BIGSERIAL NOT NULL PRIMARY KEY,
;       name VARCHAR(64) NOT NULL,
;       email VARCHAR(128) NOT NULL,
;       created_at TIMESTAMP,
;       updated_at TIMESTAMP,
;       UNIQUE (email)
;   )>)

Triggers

Since insert-dao, update-dao and delete-dao are defined as generic functions, you can define :before, :after or :around methods on those.

(defmethod mito:insert-dao :before ((object user))
  (format t "~&Adding ~S...~%" (user-name object)))

(mito:create-dao 'user :name "Eitaro Fukamachi" :email "e.arrows@gmail.com")
;-> Adding "Eitaro Fukamachi"...
;   ;; INSERT INTO "user" ("name", "email", "created_at", "updated_at") VALUES (?, ?, ?, ?) ("Eitaro Fukamachi", "e.arrows@gmail.com", "2016-02-16 21:13:47", "2016-02-16 21:13:47") [0 rows] | MITO.DAO:INSERT-DAO
;=> #<USER {100835FB33}>

Installation

(ql:quickload :mito)

Or, with Roswell:

ros install mito

See Also

Author

Copyright

Copyright (c) 2015 Eitaro Fukamachi (e.arrows@gmail.com)

License

Licensed under the LLGPL License.

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An ORM for Common Lisp with migrations, relationships and PostgreSQL support

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