Module: Foreigner::ConnectionAdapters::AbstractAdapter

Defined in:
lib/foreigner/connection_adapters/abstract/schema_statements.rb

Instance Method Summary collapse

Instance Method Details

#add_foreign_key(from_table, to_table, options = {}) ⇒ Object

Adds a new foreign key to the from_table, referencing the primary key of to_table

The foreign key will be named after the from and to tables unless you pass :name as an option.

Examples
Creating a foreign key
add_foreign_key(:comments, :posts)

generates

ALTER TABLE `comments` ADD CONSTRAINT
   `comments_post_id_fk` FOREIGN KEY (`post_id`) REFERENCES `posts` (`id`)
Creating a named foreign key
add_foreign_key(:comments, :posts, name: 'comments_belongs_to_posts')

generates

ALTER TABLE `comments` ADD CONSTRAINT
   `comments_belongs_to_posts` FOREIGN KEY (`post_id`) REFERENCES `posts` (`id`)
Creating a cascading foreign_key on a custom column
add_foreign_key(:people, :people, column: 'best_friend_id', dependent: :nullify)

generates

ALTER TABLE `people` ADD CONSTRAINT
   `people_best_friend_id_fk` FOREIGN KEY (`best_friend_id`) REFERENCES `people` (`id`)
   ON DELETE SET NULL

Supported options

:column

Specify the column name on the from_table that references the to_table. By default this is guessed to be the singular name of the to_table with “_id” suffixed. So a to_table of :posts will use “post_id” as the default :column.

:primary_key

Specify the column name on the to_table that is referenced by this foreign key. By default this is assumed to be “id”.

:name

Specify the name of the foreign key constraint. This defaults to use from_table and foreign key column.

:dependent

If set to :delete, the associated records in from_table are deleted when records in to_table table are deleted. If set to :nullify, the foreign key column is set to NULL.

:options

Any extra options you want appended to the foreign key definition.



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# File 'lib/foreigner/connection_adapters/abstract/schema_statements.rb', line 83

def add_foreign_key(from_table, to_table, options = {})
end

#create_table(table_name, *args, &block) ⇒ Object 



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# File 'lib/foreigner/connection_adapters/abstract/schema_statements.rb', line 12

def create_table(table_name, *args, &block)
  definition = nil
  super do |td|
    definition = td # This is my trick to get the definition
    block.call(td) unless block.nil?
  end
  definition.foreign_keys.each do |to_table, options_list|
    options_list.each do |options|
      add_foreign_key(table_name, to_table, options)
    end
  end
end

#foreign_key_exists?(table_name, options) ⇒ Boolean

Checks to see if a foreign key exists on a table for a given constraint.

# Check a foreign key exists
foreign_key_exists?(:suppliers, :companies)

# Check a foreign key with a custom name exists
foreign_key_exists?(:suppliers, name: "fk_company_id")

# Check a foreign key on a column
foreign_key_exists?(:suppliers, column: "company_id")

Returns:

  • (Boolean) 


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# File 'lib/foreigner/connection_adapters/abstract/schema_statements.rb', line 40

def foreign_key_exists?(table_name, options)
end

#foreign_keys(table_name) ⇒ Object

Return the foreign keys for the schema_dumper



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# File 'lib/foreigner/connection_adapters/abstract/schema_statements.rb', line 99

def foreign_keys(table_name)
  []
end

#remove_foreign_key(from_table, options) ⇒ Object

Remove the given foreign key from the table.

Examples
Remove the suppliers_company_id_fk in the suppliers table.
remove_foreign_key :suppliers, :companies
Remove the foreign key named accounts_branch_id_fk in the accounts table.
remove_foreign_key :accounts, column: :branch_id
Remove the foreign key named party_foreign_key in the accounts table.
remove_foreign_key :accounts, name: :party_foreign_key



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# File 'lib/foreigner/connection_adapters/abstract/schema_statements.rb', line 95

def remove_foreign_key(from_table, options)
end

#supports_foreign_keys? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/foreigner/connection_adapters/abstract/schema_statements.rb', line 25

def supports_foreign_keys?
  false
end