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In Rails 4.2, when creating a table or adding a reference via references or add_reference how do you specify that the foreign key should cascade on delete.
Command to generate scaffold:
rails g scaffold Child parent:references name:string Resulting migration:
create_table :childs do |t| t.references :parent, index: true, foreign_key: true t.string :name t.timestamps null: false end 
842
Should we use on delete cascade? Yes, the use of ON DELETE CASCADE is fine, but only when the dependent rows are really a logical extension of the row being deleted.
DELETE CASCADE: When we create a foreign key using this option, it deletes the referencing rows in the child table when the referenced row is deleted in the parent table which has a primary key.
ON DELETE CASCADE clause in MySQL is used to automatically remove the matching records from the child table when we delete the rows from the parent table. It is a kind of referential action related to the foreign key.
This should work
create_table :childs do |t| t.references :parent, index: true, foreign_key: {on_delete: :cascade} t.string :name t.timestamps null: false end According to ActiveRecord::ConnectionAdapters::TableDefinition#references, if a hash is specified on the foreign_key option, it is directly passed down into the foreign_key method.
source:
foreign_key(col.to_s.pluralize, foreign_key_options.is_a?(Hash) ? foreign_key_options : {}) if foreign_key_options If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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