mito
2024-10-12
Abstraction layer for DB schema
Mito
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_atandupdated_atby 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.
If you are using clack as your webserver, A middleware is provided.
(clack:clackup (lack:builder (:mito '(:sqlite3 :database-name #P"/tmp/myapp.db")) ... *app*))
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.
:col-type Definitions with Qualifiers
For some data types there are qualifiers available.
When there is only one qualfier in the data type, it can be given like in the following example
(name :col-type (:varchar 64))
However, when there is more than one qualifier, providing a list of qualifiers does not currently work.
A workaround that works is giving the whole data type definition, including the qualifier, as a string.
For example the following will work:
(price :col-type "numeric(10,2)")
However note that the following examples will not work:
(price :col-type (:numeric "10,2")) (price :col-type (:numeric 10 2))
Common Lisp does not accept parenthesis and commas as valid variable names, so :numeric(10,2) and :numeric10,2 are obviously invalid.
Keep this in mind in particular when using NUMERIC, DECIMAL, and spatial data types.
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 "[email protected]")) ;=> USER (mito:insert-dao me) ;-> ;; INSERT INTO `user` (`name`, `email`, `created_at`, `updated_at`) VALUES (?, ?, ?, ?) ("Eitaro Fukamachi", "[email protected]", "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 "[email protected]") ;; 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", "[email protected]", "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
Custom queries
Mito is at its core a rather thin wrapper around sxql and cl-dbi for converting sql results to special types and back. Most of the porcelain functions shown above are acutally implemented in just under 200 lines.
Given a plist which represents the result from the database, you can apply make-dao-instance To make it into a dao-class automatically doing inflation/deflation.
To run a custom query, use retrieve-by-sql which returns a list of plists.
(mito:retrieve-by-sql (select (:user.*) (from :users) ;; Using a subquery to avoid a join and distinct ;; Make sure you actually test performance before doing this in production (where (:in :user.name (select (:poster) (from :tweets) (where (:> :tweets.likes 1000)) (returning :poster)))))) ;=> ((:name "Shinmera" :email "[email protected]" :followers 200000) ; (:name "Fukamachi" :email "[email protected]" :followers 100000) ...)
You can use select-by-sql if you want to automatically convert it to a class.
(mito:select-by-sql 'user (select (:user.*) (from :users) (where (:in :user.name (select (:poster) (from :tweets) (where (:> :tweets.likes 1000)) (returning :poster)))))) ;=> (#<USER {1003E769E3}> #<USER {10040637A3}>)
The actual definition is basically mapcar #'make-dao-instance over the results of retrieve-by-sql
Finally select-dao provides the highest level API. This is usually what you need.
(mito:select-dao 'user (where (:in :user.name (select (:poster) (from :tweets) (where (:> :tweets.likes 1000)) (returning :poster))))) ;=> (#<USER {1003E769E3}> #<USER {10040637A3}>)
It also provides neat facilities such as an includes clause so that you don't have to write out joins by hand (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 "[email protected]") ;-> Adding "Eitaro Fukamachi"... ; ;; INSERT INTO "user" ("name", "email", "created_at", "updated_at") VALUES (?, ?, ?, ?) ("Eitaro Fukamachi", "[email protected]", "2016-02-16 21:13:47", "2016-02-16 21:13:47") [0 rows] | MITO.DAO:INSERT-DAO ;=> #<USER {100835FB33}>
Iteration (Experimental)
do-select is a macro to iterate over results from SELECT one by one. It's the same as cl:loop, but it uses CURSOR for PostgreSQL, which can reduce memory usage since it won't load whole results on memory.
(do-select (dao (select-dao 'user (where (:< "2024-07-01" :created_at)))) ;; Can be a more complex condition (when (equal (user-name dao) "Eitaro") (return dao))) ;; Same but without using CURSOR (loop for dao in (select-dao 'user (where (:< "2024-07-01" :created_at))) when (equal (user-name dao) "Eitaro") do (return dao))
The query form must be one of select-dao, retrieve-dao, or select-by-sql.
Installation
(ql:quickload :mito)
Or, with Roswell:
ros install mito
If you build a binary, reference a DB driver in your dependencies:
:dbd-sqlite3 :dbd-mysql :dbd-postgres
See Also
Author
- Eitaro Fukamachi ([email protected])
Copyright
Copyright (c) 2015 Eitaro Fukamachi ([email protected])
License
Licensed under the BSD 3-Clause License.