Define validations directly in DB as MySQL constraints and integrate them into your model transparently. See mv-core for details. There you will be able to review high level project information. Below you can see details of the migration validations that are supported by MySQL driver.

#Table Of Contents

• Validations
  • uniqueness
  • length
  • inclusion
  • exclusion
  • presence
  • absence
  • format
  • custom
• [Version History](#version history)
• Contributing

Examples:

validate uniqueness of the column 'column_name':

def up
  validates :table_name, :column_name, uniqueness: true
end

def down
  validates :table_name, :column_name, uniqueness: false
end

define validation as trigger with specified failure message:

def up
  validates :table_name, :column_name,
            uniqueness: { message: 'Error message', as: :trigger }
end

def down
  validates :table_name, :column_name, uniqueness: false
end

define validation as unique index:

def up
  validates :table_name, :column_name, uniqueness: { as: :index }
end

def down
  validates :table_name, :column_name, uniqueness: false
end

all above are available in a create and change table blocks:

def change
  create_table :table_name do |t|
     t.string :column_name, validates: { uniqueness: true }
  end
end

def up
  change :table_name do |t|
     t.change :column_name, :string, :validates: { uniqueness: true }
  end
end

def down
  change :table_name do |t|
     t.change :column_name, :string, :validates: { uniqueness: false }
  end
end

simplifications (version >= 2.1 is required):

def change
  create_table :table_name do |t|
     t.string :column_name, uniqueness: true
  end
end

Options:

• message - text of the error message that will be shown if constraint violated. Ignored unless :as == :trigger
• index_name - name of the index that will be created for validator. Ignored unless :as == :index
• on - validation event. Possible values [:save, :update, :create]. Ignored unless :as == :trigger. Default value :save
• create_tigger_name - name of the 'before insert' trigger that will be created if :as == :trigger && :on in [:save, :create]
• update_tigger_name - name of the 'before update' trigger that will be created if :as == :trigger && :on in [:save, :update]
• allow_nil - ignore validation for nil values. Ignored unless :as == :trigger. Default value: false
• allow_blank - ignore validation for blank values. Ignored unless :as == :trigger. Default value: false
• as - defines the way how constraint will be implemented. Possible values: [:index, :trigger]. Default value: :index

Examples:

column value length should be more than 4 symbols and less than 9. Otherwise 'Wrong length message' error will be raised:

 def up
   validates :table_name, :column_name,
                          length: { in: 5..8,
                                    message: 'Wrong length message' }
 end

 def down
   validates :table_name, :column_name, length: false
 end

allow NULL:

def up
  validates :table_name, :column_name,
                         length: { is: 3, allow_nil: true}
end

def down
  validates :table_name, :column_name, length: false
end

allow blank values:

def up
  validates :table_name, :column_name,
                       length: { maximum: 3,
                                 too_long: 'Value is longer than 3 symbols' }
end

def down
  validates :table_name, :column_name, length: false
end

all above are available in a create and change table blocks:

def change
  create_table :table_name do |t|
     t.string :column_name, validates: { length: { is: 3, allow_nil: true} }
  end
end

def up
  change :table_name do |t|
     t.change :column_name, :string, validates: { length: { is: 3 } }
  end
end

def down
  change :table_name do |t|
     t.change :column_name, :string, validates: { length: false }
  end
end

simplifications (version >= 2.1 is required):

def change
  create_table :table_name do |t|
    t.string :string_3, length: 3
    t.string :string_from_1_to_3, length: 1..3,
    t.string :string_1_or_3, length: [1, 3]
    t.string :string_4, validates: { length: 4 }
    t.string :string_4_in_trigger: length: { is: 4, as: :trigger }
  end
end

Options:

• in- range or array that length of the value should be contained in.
• within - synonym of :in
• is- exact length of the value
• maximum- maximum allowed length
• minimum- minimum allowed length
• message- message that should be shown if validation failed and specific message is not defined. Ignored unless :as == :trigger
• too_long- message that will be shown if value longer than allowed. Ignored unless maximum value is defined
• too_short- message that will be shown if value shorter than allowed. Ignored unless minimum value is defined
• on- validation event. Possible values [:save, :update, :create]. Default value: :save
• create_tigger_name- Name of the 'before insert' trigger
• update_tigger_name- Name of the 'before update' trigger
• allow_nil- ignore validation for nil values. Default value: false
• allow_blank- ignore validation for blank values. Default value: false
• as- defines the way how constraint will be implemented. Possible values: [:trigger]

Examples:

valid values array:

def up
  validates :table_name, :column_name, inclusion: { in: [1, 2, 3] }
end

def up
  validates :table_name, :column_name, inclusion: false
end

with failure message specified:

def up
validates :table_name, :column_name,
  inclusion: { in: [1, 2, 3],
               message: "Column value should be equal to 1 or 2 or 3" }
end

def down
  validates :table_name, :column_name, inclusion: false
end

all above are available in a create and change table blocks:

def change
  create_table :table_name do |t|
     t.integer :column_name, validates: { inclusion: { in: 1..3 } }
  end
end

def up
  change :table_name do |t|
     t.change :column_name, :integer, validates: { inclusion: { in: 1..3 } }
  end
end

def down
  change :table_name do |t|
     t.change :column_name, :integer, validates: { inclusion: false }
  end
end

simplifications (version >= 2.1 is required):

def change
  create_table :table_name do |t|
    t.string :str_or_str_1, inclusion: ['str', 'str1']
    t.string :from_str_to_str_1, inclusion: 'str'..'str1'
    t.string :str_or_str_1_in_trigger, inclusion: { in: ['str', 'str1'],
                                                    as: :trigger}
  end
end

Options:

• in - range or array that column value should be contained in.
• message - that should be shown if validation failed. Ignored unless :as == :trigger
• on - validation event. Possible values [:save, :update, :create]. Default value: :save
• create_tigger_name - Name of the 'before insert' trigger
• update_tigger_name - Name of the 'before update' trigger
• allow_nil - ignore validation for nil values. Default value: false
• allow_blank - ignore validation for blank values. Default value: false
• as - defines the way how constraint will be implemented. Possible values: [:trigger]

Examples:

exclude 1, 2, and 3:

def up
  validates :table_name, :column_name, exclusion: { in: [1, 2, 3] }
end

def down
  validates :table_name, :column_name, exclusion: false
end

the same with failure message:

def up
  validates :table_name, :column_name,
    exclusion: {
      in: [1, 2, 3],
      message: "Column value should not  be equal to 1 or 2 or 3" }
end

def down
  validates :table_name, :column_name, exclusion: false
end

all above are available in a create and change table blocks:

def change
  create_table :table_name do |t|
     t.integer :column_name, validates: { exclusion: { in: 1..3 } }
  end
end

def up
  change :table_name do |t|
     t.change :column_name, :integer, validates: { exclusion: { in: 1..3 } }
  end
end

def down
  change :table_name do |t|
     t.change :column_name, :integer, validates: { exclusion: false }
  end
end

simplifications (version >= 2.1 is required):

def change
  create_table :table_name do |t|
    t.string :neither_str_nor_str_1, exclusion: ['str', 'str1']
    t.string :from_str_to_str_1, exclusion: 'str'..'str1'
    t.string :str_or_str_1_in_trigger, exclusion: { in: ['str', 'str1'],
                                                    as: :trigger}
  end
end

Options:

• in - range or array that column value should NOT be contained in.
• message - message that should be shown if validation failed. Ignored unless :as == :trigger
• on - validation event. Possible values [:save, :update, :create]. Default value: :save
• create_tigger_name - Name of the 'before insert' trigger
• update_tigger_name - Name of the 'before update' trigger
• allow_nil - ignore validation for nil values. Default value: false
• allow_blank - ignore validation for blank values. Default value: false
• as - defines the way how constraint will be implemented. Possible values: [:trigger]

Examples:

def up
  validates :table_name, :column_name, presence: true
end

def down
  validates :table_name, :column_name, presence: false
end

with failure message:

def up
  validates :table_name, :column_name,
                  presence: { message: 'value should not be empty' }
end

def down
  validates :table_name, :column_name, presence: false
end

check when record is inserted only:

def up
  validates :table_name, :column_name,
                  presence: { message: 'value should not be empty',
                              as: :trigger,
                              on: :create }
end

def down
  validates :table_name, :column_name, presence: false
end

all above are available in a create and change table blocks:

def change
  create_table :table_name do |t|
     t.string :column_name, validates: { presence: true }
  end
end

def up
  change :table_name do |t|
     t.change :column_name, :string, validates: { presence: true }
  end
end

def down
  change :table_name do |t|
     t.change :column_name, :string, validates: false
  end
end

simplifications (version >= 2.1 is required):

def change
  create_table :table_name do |t|
    t.string :presence_in_check, presence: true
    t.string :presence_in_trigger, presence: { as: :trigger, on: :create }
  end
end

Options:

• message - message that should be shown if validation failed. Ignored unless :as == :trigger
• on - validation event. Possible values [:save, :update, :create]. Ignored unless :as == :trigger. Default value: :save
• create_tigger_name - Name of the 'before insert' trigger that will be created if :as == :trigger && :on in [:save, :create]
• update_tigger_name - Name of the 'before update' trigger that will be created if :as == :trigger && :on in [:save, :update]
• allow_nil - ignore validation for nil values. Default value: false
• allow_blank - ignore validation for blank values. Default value: false
• as - defines the way how constraint will be implemented. Possible values: [:trigger] Default value: :trigger

Examples:

def up
  validates :table_name, :column_name, absence: true
end

def down
  validates :table_name, :column_name, absence: false
end

with failure message:

def up
  validates :table_name, :column_name,
                  absence: { message: 'value should be empty' }
end

def down
  validates :table_name, :column_name, absence: false
end

check when record is inserted only:

def up
  validates :table_name, :column_name,
                  absence: { message: 'value should be empty',
                              as: :trigger,
                              on: :create }
end

def down
  validates :table_name, :column_name, absence: false
end

all above are available in a create and change table blocks:

def change
  create_table :table_name do |t|
     t.string :column_name, validates: { absence: true }
  end
end

def up
  change :table_name do |t|
     t.change :column_name, :string, validates: { absence: true }
  end
end

def down
  change :table_name do |t|
     t.change :column_name, :string, validates: { absence: false }
  end
end

simplifications (version >= 2.1 is required):

def change
  create_table :table_name do |t|
    t.string :absence_in_check, absence: true
    t.string :absence_in_trigger, absence: { as: :trigger, on: :create }
  end
end

Options:

• message - message that should be shown if validation failed. Ignored unless :as == :trigger
• on - validation event. Possible values [:save, :update, :create]. Ignored unless :as == :trigger. Default value: :save
• create_tigger_name - Name of the 'before insert' trigger that will be created if :as == :trigger && :on in [:save, :create]
• update_tigger_name - Name of the 'before update' trigger that will be created if :as == :trigger && :on in [:save, :update]
• allow_nil - ignore validation for nil values. Default value: true
• allow_blank - ignore validation for blank values. Default value: true
• as - defines the way how constraint will be implemented. Possible values: [:trigger] Default value: :trigger

Examples:

allows only values that contains 'word' inside:

def up
  validates :table_name, :column_name, format: { with: /word/ }
end

def down
  validates :table_name, :column_name, format: false
end

with failure message:

def up
validates :table_name, :column_name,
  format: { with: /word/,
            message: 'Column_name value should contain start word' }
end

def down
  validates :table_name, :column_name, format: false
end

implemented as trigger:

def up
  validates :table_name, :column_name,
    format: { with: /word/,
              message: 'Column_name value should contain start word',
              as: :trigger }
end

def down
  validates :table_name, :column_name, format: false
end

all above are available in a create and change table blocks:

def change
  create_table :table_name do |t|
    t.string :column_name, validates { format: { with: /word/ } }
  end
end

def up
  change :table_name do |t|
    t.change :column_name, :string, validates: { format: { with: /word/ } }
  end
end

def down
  change :table_name do |t|
    t.change :column_name, :string, validates: { format: false }
  end
end

simplifications (version >= 2.1 is required):

def change
  create_table :table_name do |t|
    t.string :contains_word, format: /word/
    t.string :contains_word_in_trigger, format: { with: /word/,
                                                  as: :trigger }
  end
end

Options:

• with - regular expression that column value should be matched to
• message - message that should be shown if validation failed. Ignored unless :as == :trigger
• on - validation event. Possible values [:save, :update, :create]. Ignored unless :as == :trigger. Default value: :save
• create_tigger_name - Name of the 'before insert' trigger that will be created if :as == :trigger && :on in [:save, :create]
• update_tigger_name - Name of the 'before update' trigger that will be created if :as == :trigger && :on in [:save, :update]
• allow_nil - ignore validation for nil values. Default value: false
• allow_blank - ignore validation for blank values. Default value: false
• as - defines the way how constraint will be implemented. Possible values: [:trigger] Default value: :trigger

(version >= 2.1 is required)

Examples:

allows only values that equals 'word' when trimmed:

def up
  validates :table_name, :column_name,
                        custom: { statement: "TRIM({column_name}) = 'word'" }
end

def down
  validates :table_name, :column_name, custom: false
end

with failure message:

def up
  validates :table_name, :column_name,
    custom: { statement: "TRIM({column_name}) = 'word'",
              message: 'Column_name value should contain start word' }
end

def down
  validates :table_name, :column_name, custom: false
end

implemented as trigger on insert event:

def up
  validates :table_name, :column_name,
    custom: { statement: "TRIM({column_name}) = 'word'",
              message: 'Column_name value should contain start word',
              as: :trigger,
              on: :create }
end

def down
  validates :table_name, :column_name, custom: false
end

all above are available in a create and change table blocks:

def change
  create_table :table_name do |t|
    t.string :column_name,
          validates: { custom: { statement: "TRIM({column_name}) = 'word'"} }
  end
end

def up
  change :table_name do |t|
    t.change :column_name, :string,
          validates: { custom: { statement: "TRIM({column_name}) = 'word'"} }
  end
end

def down
  change :table_name do |t|
    t.change :column_name, :string, validates: { custom: false }
  end
end

simplifications (version >= 2.1 is required):

def change
  create_table :table_name do |t|
    t.string :contains_word, custom: "TRIM({contains_word}) = 'word'"
    t.string :contains_word_synonym,
             validates: "TRIM({contains_word_synonym}) = 'word'"
    t.string :contains_word_in_trigger,
             custom: { statement: "TRIM({contains_word_in_trigger}) = 'word'",          as: :trigger }
  end
end

Options:

• message - message that should be shown if validation failed. Ignored unless :as == :trigger
• on validation event. Possible values [:save, :update, :create]. Default value: :save
• create_tigger_name - name of the 'before insert' trigger
• update_tigger_name - name of the 'before update' trigger
• allow_nil - ignore validation for nil values. Default value: false
• allow_blank - ignore validation for blank values. Default value: false
• as - defines the way how constraint will be implemented. Possible values: [:trigger]

(2.0.0) (17 Jan, 2015)

• Completely rewritten. Migrated to Ruby 2.0 and RoR 4

(2.1.0) (22 Jan, 2015)

• Custom validation

(2.2.0) (28 Jan, 2015)

• Integration with ActiveRecord

(2.2.1) (23 May, 2015)

• Format validation

(2.2.2) (29 May, 2015)

• Made it possible to use several mv-* drivers in the same project

(2.2.3) (20 Jul, 2015)

• Fix issue with invalid parameters number in add_column and change_column methods

(2.2.4) (23 Nov, 2015)

• Do not camel case column name in error message
• Use SIGNAL to raise validation exception for MySQL >= 5.5

(2.2.5) (23 Feb, 2016)

• Suppress exception while running db:schema:load

(2.2.6) (12 Sep, 2016)

• Escape single quotes in the custom validation statement body

• Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet
• Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it
• Fork the project
• Start a feature/bugfix branch
• Commit and push until you are happy with your contribution
• Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.