File: README — Documentation for validates_lengths_from

Validates Lengths from Database

Few people add length validations to fields in their database, and when saving such fields that have exhausted their length, an SQL error occurs. This gem introspects your table schema for maximum lengths on string and text fields and automatically adds length validations to the model.

Requirements

As of v0.5.0, validates_lengths_from_database lazily loads column information and requires Rails 3+. If you are using Rails 2, please use the v0.4.0 release.

Due to issues maintaining backwards compatibility, as of v0.4.0 validates_lengths_from_database requires ruby 1.9.3 or higher. If you are still using 1.8.7 or 1.9.2, please use the v0.3.0 release.

Installation

Include the gem using bundler in your Gemfile:

gem "validates_lengths_from_database"

Usage

In your model you can activate validations:

class Post < ActiveRecord::Base
  validates_lengths_from_database
end

It also supports filter-style :only and :except options:

class Post < ActiveRecord::Base
  validates_lengths_from_database :only => [:title, :contents]
end

class Post < ActiveRecord::Base
  validates_lengths_from_database :except => [:other_field]
end

If you’d rather specify the limits explicitly instead of pulling them from the database, you can set it:

class Post < ActiveRecord::Base
  validates_lengths_from_database :limit => 255
end

Or to set the limit differently for string (VARCHAR) and (TEXT) columns:

class Post < ActiveRecord::Base
  validates_lengths_from_database :limit => {:string => 255, :text => 4092}
end

Note that unfortunately this cannot be done at a global level directly against ActiveRecord::Base, since the validates_length_from_database method requires the class to have a table name (with the ability to load the schema).

Running Tests

This gem uses appraisal to test with different versions of the dependencies. See Appraisal first for which versions are tested.

# Just the gems locked in Gemfile.lock
$ rake test

# All of the Appraisals:
$ appraisal install
$ appraisal rake test