Class: ActiveRecord::ConnectionAdapters::TableDefinition
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Subclasses:
|
|
Super Chains via Extension / Inclusion / Inheritance | |
Instance Chain:
self,
ColumnMethods
|
|
Inherits: | Object |
Defined in: | activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb |
Overview
Represents the schema of an SQL table in an abstract way. This class provides methods for manipulating the schema representation.
Inside migration files, the t
object in create_table is actually of this type:
class SomeMigration < ActiveRecord::Migration[7.1]
def up
create_table :foo do |t|
puts t.class # => "ActiveRecord::ConnectionAdapters::TableDefinition"
end
end
def down
#...
end
end
ColumnMethods
- Attributes & Methods
Class Method Summary
Instance Attribute Summary
- #as readonly
- #check_constraints readonly
- #comment readonly
- #foreign_keys readonly
- #if_not_exists readonly
- #indexes readonly
- #name readonly
- #options readonly
- #temporary readonly
Instance Method Summary
-
#[](name)
Returns a
ColumnDefinition
for the column with name #name. -
#belongs_to(*args, **options)
Alias for #references.
- #check_constraint(expression, **options)
-
#column(name, type, index: nil, **options)
Instantiates a new column for the table.
-
#columns
Returns an array of
ColumnDefinition
objects for the columns of the table. - #foreign_key(to_table, **options)
-
#index(column_name, **options)
Adds index options to the indexes hash, keyed by column name This is primarily used to track indexes that need to be created after the table.
-
#references(*args, **options)
(also: #belongs_to)
Adds a reference.
-
#remove_column(name)
remove the column #name from the table.
- #set_primary_key(table_name, id, primary_key, **options)
-
#timestamps(**options)
Appends
:datetime
columns:created_at
and:updated_at
to the table.
ColumnMethods
- Included
#column | Appends a column or columns of a specified type. |
#primary_key | Appends a primary key definition to the table definition. |
Constructor Details
.new(conn, name, temporary: false, if_not_exists: false, options: nil, as: nil, comment: nil) ⇒ TableDefinition
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 368
def initialize( conn, name, temporary: false, if_not_exists: false, options: nil, as: nil, comment: nil, ** ) @conn = conn @columns_hash = {} @indexes = [] @foreign_keys = [] @primary_keys = nil @check_constraints = [] @temporary = temporary @if_not_exists = if_not_exists @options = @as = as @name = name @comment = comment end
Instance Attribute Details
#as (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
#check_constraints (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
#comment (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
#foreign_keys (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
#if_not_exists (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
#indexes (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
#name (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
#options (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
#temporary (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 366
attr_reader :name, :temporary, :if_not_exists, :, :as, :comment, :indexes, :foreign_keys, :check_constraints
Instance Method Details
#[](name)
Returns a ColumnDefinition
for the column with name #name.
#belongs_to(*args, **options)
Alias for #references.
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 553
alias :belongs_to :references
#blob
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 324
alias :blob :binary
#check_constraint(expression, **options)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 522
def check_constraint(expression, ** ) check_constraints << new_check_constraint_definition(expression, ) end
#column(name, type, index: nil, **options)
Instantiates a new column for the table. See connection.add_column for available options.
Additional options are:
-
:index
- Create an index for the column. Can be eithertrue
or an options hash.
This method returns self
.
Examples
# Assuming {td} is an instance of TableDefinition
td.column(:granted, :boolean, index: true)
Short-hand examples
Instead of calling #column
directly, you can also work with the short-hand definitions for the default types. They use the type as the method name instead of as a parameter and allow for multiple columns to be defined in a single statement.
What can be written like this with the regular calls to column:
create_table :products do |t|
t.column :shop_id, :integer
t.column :creator_id, :integer
t.column :item_number, :string
t.column :name, :string, default: "Untitled"
t.column :value, :string, default: "Untitled"
t.column :created_at, :datetime
t.column :updated_at, :datetime
end
add_index :products, :item_number
can also be written as follows using the short-hand:
create_table :products do |t|
t.integer :shop_id, :creator_id
t.string :item_number, index: true
t.string :name, :value, default: "Untitled"
t. null: false
end
There’s a short-hand method for each of the type values declared at the top. And then there’s #timestamps that’ll add created_at
and updated_at
as datetimes.
#references will add an appropriately-named _id column, plus a corresponding _type column if the :polymorphic
option is supplied. If :polymorphic
is a hash of options, these will be used when creating the _type
column. The :index
option will also create an index, similar to calling add_index. So what can be written like this:
create_table :taggings do |t|
t.integer :tag_id, :tagger_id, :taggable_id
t.string :tagger_type
t.string :taggable_type, default: 'Photo'
end
add_index :taggings, :tag_id, name: 'index_taggings_on_tag_id'
add_index :taggings, [:tagger_id, :tagger_type]
Can also be written as follows using references:
create_table :taggings do |t|
t.references :tag, index: { name: 'index_taggings_on_tag_id' }
t.references :tagger, polymorphic: true
t.references :taggable, polymorphic: { default: 'Photo' }, index: false
end
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 489
def column(name, type, index: nil, ** ) name = name.to_s type = type.to_sym if type raise_on_duplicate_column(name) @columns_hash[name] = new_column_definition(name, type, ** ) if index = index.is_a?(Hash) ? index : {} index(name, ** ) end self end
#columns
Returns an array of ColumnDefinition
objects for the columns of the table.
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 415
def columns; @columns_hash.values; end
#foreign_key(to_table, **options)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 518
def foreign_key(to_table, ** ) foreign_keys << new_foreign_key_definition(to_table, ) end
#index(column_name, **options)
Adds index options to the indexes hash, keyed by column name This is primarily used to track indexes that need to be created after the table
index(:account_id, name: 'index_projects_on_account_id')
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 514
def index(column_name, ** ) indexes << [column_name, ] end
#numeric
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 325
alias :numeric :decimal
#references(*args, **options) Also known as: #belongs_to
Adds a reference.
t.references(:user)
t.belongs_to(:supplier, foreign_key: true)
t.belongs_to(:supplier, foreign_key: true, type: :integer)
See connection.add_reference for details of the options you can use.
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 548
def references(*args, ** ) args.each do |ref_name| ReferenceDefinition.new(ref_name, ** ).add_to(self) end end
#remove_column(name)
remove the column #name from the table.
remove_column(:account_id)
#set_primary_key(table_name, id, primary_key, **options)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 392
def set_primary_key(table_name, id, primary_key, ** ) if id && !as pk = primary_key || Base.get_primary_key(table_name.to_s.singularize) if id.is_a?(Hash) .merge!(id.except(:type)) id = id.fetch(:type, :primary_key) end if pk.is_a?(Array) primary_keys(pk) else primary_key(pk, id, ** ) end end end
#timestamps(**options)
Appends :datetime
columns :created_at
and :updated_at
to the table. See connection.add_timestamps
t. null: false
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 530
def (** ) [:null] = false if [:null].nil? if ! .key?(:precision) && @conn.supports_datetime_with_precision? [:precision] = 6 end column(:created_at, :datetime, ** ) column(:updated_at, :datetime, ** ) end