Module: MigrationConstraintHelpers

Defined in:
lib/migration_helpers/lib/migration_helper.rb

Instance Method Summary collapse

Instance Method Details

#drop_foreign_key(table, field) ⇒ Object

Drops a foreign key from table.field that has been created before with foreign_key method

table: The table name field: A field (or array of fields) of the table



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# File 'lib/migration_helpers/lib/migration_helper.rb', line 22

def drop_foreign_key(table, field)
   execute "ALTER TABLE #{table} DROP FOREIGN KEY #{constraint_name(table, field)}"
end

#foreign_key(table, field, referenced_table, referenced_field = :id, cascade = true) ⇒ Object

Creates a foreign key from table.field against referenced_table.referenced_field

table: The tablename field: A field of the table referenced_table: The table which contains the field referenced referenced_field: The field (which should be part of the primary key) of the referenced table cascade: delete & update on cascade?



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# File 'lib/migration_helpers/lib/migration_helper.rb', line 10

def foreign_key(table, field, referenced_table, referenced_field = :id, cascade = true)
   execute "ALTER TABLE #{table} ADD CONSTRAINT #{constraint_name(table, field)}
            FOREIGN KEY #{constraint_name(table, field)} (#{field_list(field)})
            REFERENCES #{referenced_table}(#{field_list(referenced_field)})
            #{(cascade ? 'ON DELETE CASCADE ON UPDATE CASCADE' : '')}"
end

#primary_key(table, field) ⇒ Object

Creates a primary key for table, which right now HAS NOT primary key defined

table: The table name field: A field (or array of fields) of the table that will be part of the primary key



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# File 'lib/migration_helpers/lib/migration_helper.rb', line 30

def primary_key(table, field)
   execute "ALTER TABLE #{table} ADD PRIMARY KEY(#{field_list(field)})"
end