Class: Reform::Form::UniqueValidator

Inherits:
ActiveModel::EachValidator
  • Object
show all
Defined in:
lib/reform/form/validation/unique_validator.rb

Overview

Unique Validation

Reform’s own implementation for uniqueness which does not write to model

Usage

Pass a true boolean value to validate a field against all values available in the database: validates :title, unique: true

Options

Scope

A scope can be use to filter the records that need to be compare with the current value to validate. A scope array can have one to many fields define.

A scope can be define the following ways: validates :title, unique: { scope: :album_id } validates :title, unique: { scope: [:album_id] } validates :title, unique: { scope: [:album_id, …] }

All fields included in a scope must be declared as a property like this: property :album_id validates :title, unique: { scope: :album_id }

Just remove write access to the property if the field must not be change: property :album_id, writeable: false validates :title, unique: { scope: :album_id }

This use case is useful if album_id is set to a Song this way: song = album.songs.new album_id is automatically set and can’t be change by the operation

Instance Method Summary collapse

Instance Method Details

#validate_each(form, attribute, value) ⇒ Object 



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# File 'lib/reform/form/validation/unique_validator.rb', line 32

def validate_each(form, attribute, value)
  model = form.model_for_property(attribute)

  # search for models with attribute equals to form field value
  query = model.class.where(attribute => value)

  # apply scope if options has been declared
  Array(options[:scope]).each do |field|
    # add condition to only check unique value with the same scope
    query = query.where(field => form.send(field))
  end

  # if model persisted, query may return 0 or 1 rows, else 0
  allow_count = model.persisted? ? 1 : 0
  form.errors.add(attribute, :taken) if query.count > allow_count
end