method

add_reference

v4.0.2 - Show latest stable - 1 note - Class: ActiveRecord::ConnectionAdapters::SchemaStatements

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What's this?

add_reference(table_name, ref_name, options = {}) public

Adds a reference. Optionally adds a type column, if :polymorphic option is provided. add_reference and add_belongs_to are acceptable.

Create a user_id column

add_reference(:products, :user)

Create a supplier_id and supplier_type columns

add_belongs_to(:products, :supplier, polymorphic: true)

Create a supplier_id, supplier_type columns and appropriate index

add_reference(:products, :supplier, polymorphic: true, index: true)

Show source

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 604
      def add_reference(table_name, ref_name, options = {})
        polymorphic = options.delete(:polymorphic)
        index_options = options.delete(:index)
        add_column(table_name, "#{ref_name}_id", :integer, options)
        add_column(table_name, "#{ref_name}_type", :string, polymorphic.is_a?(Hash) ? polymorphic : options) if polymorphic
        add_index(table_name, polymorphic ? ]id type].map{ |t| "#{ref_name}_#{t}" } : "#{ref_name}_id", index_options.is_a?(Hash) ? index_options : nil) if index_options
      end

June 7, 2016

0 thanks

foreign_key option

It is also possible to specify that add_foreign_key should be added to the schema:

add_reference(:products, :supplier, foreign_key: true)

add_reference

Related methods

Create a user_id column

Create a supplier_id and supplier_type columns

Create a supplier_id, supplier_type columns and appropriate index

foreign_key option