method

column_exists?

v3.0.9 - Show latest stable - 2 notes - Class: ActiveRecord::ConnectionAdapters::SchemaStatements

column_exists?(table_name, column_name, type = nil, options = {}) public

Checks to see if a column exists in a given table.

Examples

# Check a column exists
column_exists?(:suppliers, :name)

# Check a column exists of a particular type
column_exists?(:suppliers, :name, :string)

# Check a column exists with a specific definition
column_exists?(:suppliers, :name, :string, :limit => 100)

Show source

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 66
      def column_exists?(table_name, column_name, type = nil, options = {})
        columns(table_name).any?{ |c| c.name == column_name.to_s &&
                                      (!type                 || c.type == type) &&
                                      (!options[:limit]      || c.limit == options[:limit]) &&
                                      (!options[:precision]  || c.precision == options[:precision]) &&
                                      (!options[:scale]      || c.scale == options[:scale]) }
      end

January 20, 2012

1 thank

Example

Check if id column exists in users table

ActiveRecord::Base.connection.column_exists?(:users, :id)

February 20, 2013

0 thanks

It also works with strings

It works with strings:

ActiveRecord::Base.connection.column_exists?('users', 'id')

Which is helpful if you need to specify the database/schema to use:

ActiveRecord::Base.connection.column_exists?('secondary.users', 'id')

column_exists?

Related methods

Examples

Example

It also works with strings