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Diffstat (limited to 'guides/source/active_record_basics.md')
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diff --git a/guides/source/active_record_basics.md b/guides/source/active_record_basics.md index 182bc865f0..d765e32ac7 100644 --- a/guides/source/active_record_basics.md +++ b/guides/source/active_record_basics.md @@ -1,4 +1,4 @@ -**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.** +**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON https://guides.rubyonrails.org.** Active Record Basics ==================== @@ -29,7 +29,7 @@ Object Relational Mapping system. ### The Active Record Pattern -[Active Record was described by Martin Fowler](http://www.martinfowler.com/eaaCatalog/activeRecord.html) +[Active Record was described by Martin Fowler](https://www.martinfowler.com/eaaCatalog/activeRecord.html) in his book _Patterns of Enterprise Application Architecture_. In Active Record, objects carry both persistent data and behavior which operates on that data. Active Record takes the opinion that ensuring @@ -45,7 +45,7 @@ relationships of the objects in an application can be easily stored and retrieved from a database without writing SQL statements directly and with less overall database access code. -NOTE: If you are not familiar enough with relational database management systems (RDBMS) or structured query language (SQL), please go through [this tutorial](https://www.w3schools.com/sql/default.asp) (or [this one](http://www.sqlcourse.com/)) or study them by other means. Understanding how relational databases work is crucial to understanding Active Records and Rails in general. +NOTE: Basic knowledge of relational database management systems (RDBMS) and structured query language (SQL) is helpful in order to fully understand Active Record. Please refer to [this tutorial](https://www.w3schools.com/sql/default.asp) (or [this one](http://www.sqlcourse.com/)) or study them by other means if you would like to learn more. ### Active Record as an ORM Framework @@ -82,9 +82,9 @@ of two or more words, the model class name should follow the Ruby conventions, using the CamelCase form, while the table name must contain the words separated by underscores. Examples: -* Database Table - Plural with underscores separating words (e.g., `book_clubs`). * Model Class - Singular with the first letter of each word capitalized (e.g., `BookClub`). +* Database Table - Plural with underscores separating words (e.g., `book_clubs`). | Model / Class | Table / Schema | | ---------------- | -------------- | @@ -105,9 +105,9 @@ depending on the purpose of these columns. fields that Active Record will look for when you create associations between your models. * **Primary keys** - By default, Active Record will use an integer column named - `id` as the table's primary key. When using [Active Record - Migrations](active_record_migrations.html) to create your tables, this column will be - automatically created. + `id` as the table's primary key (`bigint` for PostgreSQL and MySQL, `integer` + for SQLite). When using [Active Record Migrations](active_record_migrations.html) + to create your tables, this column will be automatically created. There are also some optional column names that will add additional features to Active Record instances: @@ -115,12 +115,12 @@ to Active Record instances: * `created_at` - Automatically gets set to the current date and time when the record is first created. * `updated_at` - Automatically gets set to the current date and time whenever - the record is updated. + the record is created or updated. * `lock_version` - Adds [optimistic - locking](http://api.rubyonrails.org/classes/ActiveRecord/Locking.html) to + locking](https://api.rubyonrails.org/classes/ActiveRecord/Locking.html) to a model. * `type` - Specifies that the model uses [Single Table - Inheritance](http://api.rubyonrails.org/classes/ActiveRecord/Base.html#class-ActiveRecord::Base-label-Single+table+inheritance). + Inheritance](https://api.rubyonrails.org/classes/ActiveRecord/Base.html#class-ActiveRecord::Base-label-Single+table+inheritance). * `(association_name)_type` - Stores the type for [polymorphic associations](association_basics.html#polymorphic-associations). * `(table_name)_count` - Used to cache the number of belonging objects on @@ -202,6 +202,8 @@ class Product < ApplicationRecord end ``` +NOTE: Active Record does not support using non-primary key columns named `id`. + CRUD: Reading and Writing Data ------------------------------ @@ -307,12 +309,12 @@ user = User.find_by(name: 'David') user.destroy ``` -If you'd like to delete several records in bulk, you may use `destroy_all` -method: +If you'd like to delete several records in bulk, you may use `destroy_by` +or `destroy_all` method: ```ruby # find and delete all users named David -User.where(name: 'David').destroy_all +User.destroy_by(name: 'David') # delete all users User.destroy_all |