module Sequel::Plugins::PgAutoConstraintValidations

  1. lib/sequel/plugins/pg_auto_constraint_validations.rb

The pg_auto_constraint_validations plugin automatically converts some constraint violation exceptions that are raised by INSERT/UPDATE queries into validation failures. This can allow for using the same error handling code for both regular validation errors (checked before attempting the INSERT/UPDATE), and constraint violations (raised during the INSERT/UPDATE).

This handles the following constraint violations:



  • UNIQUE (except expression/functional indexes)

  • FOREIGN KEY (both referencing and referenced by)

If the plugin cannot convert the constraint violation error to a validation error, it just reraises the initial exception, so this should not cause problems if the plugin doesn't know how to convert the exception.

This plugin is not intended as a replacement for other validations, it is intended as a last resort. The purpose of validations is to provide nice error messages for the user, and the error messages generated by this plugin are fairly generic. The error messages can be customized using the :messages plugin option, but there is only a single message used per constraint type.

This plugin only works on the postgres adapter when using the pg 0.16+ driver, PostgreSQL 9.3+ server, and PostgreSQL 9.3+ client library (libpq). In other cases it will be a no-op.


album =>1) # Assume no such artist exists
rescue Sequel::ValidationFailed
  album.errors.on(:artist_id) # ['is invalid']


# Make all model subclasses automatically convert constraint violations
# to validation failures (called before loading subclasses)
Sequel::Model.plugin :pg_auto_constraint_validations

# Make the Album class automatically convert constraint violations
# to validation failures
Album.plugin :pg_auto_constraint_validations


Public Class

  1. configure


DEFAULT_ERROR_MESSAGES = { :not_null=>"is not present", :check=>"is invalid", :unique=>'is already taken', :foreign_key=>'is invalid', :referenced_by=>'cannot be changed currently' }.freeze).each_value(&:freeze)  

The default error messages for each constraint violation type.

Public Class methods

configure (model, opts=OPTS)

Setup the constraint violation metadata. Options:


Override the default error messages for each constraint violation type (:not_null, :check, :unique, :foreign_key, :referenced_by)

[show source]
   # File lib/sequel/plugins/pg_auto_constraint_validations.rb
64 def self.configure(model, opts=OPTS)
65   model.instance_exec do
66     setup_pg_auto_constraint_validations
67     @pg_auto_constraint_validations_messages = (@pg_auto_constraint_validations_messages || DEFAULT_ERROR_MESSAGES).merge(opts[:messages] || OPTS).freeze
68   end
69 end