A validation library for Crystal Objects which takes its inspiration from Valcro, a simple validation library for Ruby. There are some differences between the Crystal version and Ruby that you'll need to pay attention to.
Add this to your application's shard.yml
:
dependencies:
accord:
github: neovintage/accord
Validations can be defined within the object that needs to be validated or as separate classes. When using the inline method of validation,
an instance method of validate
needs to be defined. This allows crystal to access all of the instance variables that exist as part of the
instantiated object.
require "accord"
class Dog
include Accord
property name
def validate
errors.add(:name, "must be tough") if name != "spike"
end
end
dog = Dog.new
dog.name = "chuck"
dog.validate!
dog.valid? # false
dog.error_messages # ["name must be tough"]
dog.name = "spike"
dog.validate!
dog.valid? # true
One of the big values for this library is the ability to share validations across objects. When creating a validation as an object, the validator object must:
- Accept the object to be validated as a parameter to the constructor
- Define a
call
instance method that accepts a parameter of typeAccord::ErrorList
- Be a subclass of
Accord::Validator
require "accord"
class NameValidator < Accord::Validator
def initialize(context)
@context = context
end
def call(errors : Accord::ErrorList)
if @context.name != "spike"
errors.add(:name, "must be spike")
end
end
end
class Dog
include Accord
validates_with [ NameValidator ]
end
class Cat
include Accord
validates_with [ NameValidator ]
end
In cases where you need to be more explicit when sharing validator objects, specifying a union type to the constructor may be necessary. Here's a partial example:
alias AnimalValidationTypes = (Dog | Cat)
class NameValidator < Accord::Validator
def initialize(context : AnimalValidationTypes)
end
end
Accord can mix inline and sharable validations. In terms of the order of operations, sharable validations occur first and then inline
validations. The sharable validations are executed in the order that they're defined within the Array passed to validates_with
.
class Dog
include Accord
validates_with [ NameValidator, AgeValidator ]
def validate
errors.add(:base, "Shouldn't be barking") if night == true && barking == true
end
end
In this example, NameValidator
would be executed first, then AgeValidator
and finally the validate
method.
The ErrorList
instance acts allows you to add new errors directly with the add
instance method. When specifying the
the name of the object it must be a symbol and when that error is turned into a string, the message is appended to the
name of the symbol.
If you don't want the error message to prepend the symbol, a special symbol identifier exists called :base
.
errors = Accord::ErrorList.new
errors.add(:base, "I like writing my own error msgs")
errors.add(:name, "must be awesome")
errors.full_messages # ["I like writing my own error msgs", "name must be awesome"]
- Fork it ( https://github.com/neovintage/accord/fork )
- Create your feature branch (git checkout -b my-new-feature)
- Commit your changes (git commit -am 'Add some feature')
- Push to the branch (git push origin my-new-feature)
- Create a new Pull Request
- neovintage Rimas Silkaitis - creator, maintainer