method

add_unique_constraint

v7.1.3.2 - Show latest stable - 0 notes - Class: SchemaStatements

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What's this?

add_unique_constraint(table_name, column_name = nil, **options) public

Adds a new unique constraint to the table.

add_unique_constraint :sections, [:position], deferrable: :deferred, name: "unique_position"

generates:

ALTER TABLE "sections" ADD CONSTRAINT unique_position UNIQUE (position) DEFERRABLE INITIALLY DEFERRED

If you want to change an existing unique index to deferrable, you can use :using_index to create deferrable unique constraints.

add_unique_constraint :sections, deferrable: :deferred, name: "unique_position", using_index: "index_sections_on_position"

The options hash can include the following keys:

:name: The constraint name. Defaults to uniq_rails_<identifier>.
:deferrable: Specify whether or not the unique constraint should be deferrable. Valid values are false or :immediate or :deferred to specify the default behavior. Defaults to false.
:using_index: To specify an existing unique index name. Defaults to nil.

Show source

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 744
        def add_unique_constraint(table_name, column_name = nil, **options)
          options = unique_constraint_options(table_name, column_name, options)
          at = create_alter_table(table_name)
          at.add_unique_constraint(column_name, options)

          execute schema_creation.accept(at)
        end

add_unique_constraint

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