Data validation library based on predicate logic and rule composition.
Unlike other, well known, validation solutions in Ruby, dry-validation takes
a different approach and focuses a lot on explicitness, clarity and preciseness
of validation logic. It is designed to work with any data input, whether it's a
simple hash, an array or a complex object with deeply nested data.
It is based on an idea that each validation is encapsulated by a simple,
stateless predicate, that receives some input and returns either true or false.
Those predicates are encapsulated by rules which can be composed together using
predicate logic. This means you can use the common logic operators to build up
a validation schema.
Validations can be described with great precision, dry-validation eliminates
ambigious concepts like presence validation where we can't really say whether
some attribute or key is missing or it's just that the value is nil.
In dry-validation type-safety is a first-class feature, something that's completely
missing in other validation libraries, and it's an important and useful feature. It
means you can compose a validation that does rely on the type of a given value. In
example it makes no sense to validate each element of an array when it turns out to
be an empty string.
The core of dry-validation is rule composition and predicate logic provided by
dry-logic. The DSL is a simple front-end
for it. It only allows you to define the rules by using predicate identifiers.
There are no magical options, conditionals and custom validation blocks known from
other libraries. The focus is on pure validation logic expressed in a concise way.
The DSL is very abstract, it builds a rule AST which is compiled into an array of rule objects. This means alternative interfaces could be easily built.
Always and everywhere. This is a general-purpose validation library that can be used for many things and it's multiple times faster than ActiveRecord/ActiveModel::Validations and strong-parameters.
Possible use-cases include validation of:
- Form params
- "GET" params
- JSON documents
- YAML documents
- Application configuration (ie stored in ENV)
- Replacement for
ActiveRecord/ActiveModel::Validations - Replacement for
strong-parameters - etc.
Please refer to the wiki for full usage documentation.
UserSchema = Dry::Validation.Schema do
key(:name).required
key(:email).required(format?: EMAIL_REGEX)
key(:age).maybe(:int?)
key(:address) do
key(:street).required
key(:city).required
key(:zipcode).required
end
end
UserSchema.(
name: 'Jane',
email: 'jane@doe.org',
address: { street: 'Street 1', city: 'NYC', zipcode: '1234' }
).inspect
# #<Dry::Validation::Result output={:name=>"Jane", :email=>"jane@doe.org", :address=>{:street=>"Street 1", :city=>"NYC", :zipcode=>"1234"}} messages={:age=>["age is missing"]}>This library is in an early stage of development but you are encouraged to try it out and provide feedback.
For planned features check out the issues.
See LICENSE file.