instance method
change_table
Ruby on Rails 3.2.22.5
Signature
change_table(table_name, options = {})A block for changing columns in table.
Example
# change_table() yields a Table instance
change_table(:suppliers) do |t|
t.column :name, :string, :limit => 60
# Other column alterations here
end
The options hash can include the following keys:
:bulk-
Set this to true to make this a bulk alter query, such as ALTER TABLE
usersADD COLUMN age INT(11), ADD COLUMN birthdate DATETIME …Defaults to false.
Examples
Add a column
change_table(:suppliers) do |t|
t.column :name, :string, :limit => 60
end
Add 2 integer columns
change_table(:suppliers) do |t|
t.integer :width, :height, :null => false, :default => 0
end
Add created_at/updated_at columns
change_table(:suppliers) do |t|
t.timestamps
end
Add a foreign key column
change_table(:suppliers) do |t|
t.references :company
end
Creates a company_id(integer) column
Add a polymorphic foreign key column
change_table(:suppliers) do |t|
t.belongs_to :company, :polymorphic => true
end
Creates company_type(varchar) and company_id(integer) columns
Remove a column
change_table(:suppliers) do |t|
t.remove :company
end
Remove several columns
change_table(:suppliers) do |t|
t.remove :company_id
t.remove :width, :height
end
Remove an index
change_table(:suppliers) do |t|
t.remove_index :company_id
end
See also Table for details on all of the various column transformation
Parameters
-
table_namereq -
optionsopt = {}
Source
# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 237
def change_table(table_name, options = {})
if supports_bulk_alter? && options[:bulk]
recorder = ActiveRecord::Migration::CommandRecorder.new(self)
yield Table.new(table_name, recorder)
bulk_change_table(table_name, recorder.commands)
else
yield Table.new(table_name, self)
end
end
Defined in activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb line 237
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Defined in ActiveRecord::ConnectionAdapters::SchemaStatements