Custom Validation for schema attributes

[arvindand]

Hi, I went through the documentation but could only find a guide for a custom validation annotation on the bean, is there a plan to support adding custom validation annotations in the generated models for the attributes of a bean?

[hauner]

there is no existing plan. If we come up with a usable configuration I can probably add it.

Can you provide an example what you have in mind?

a few quick thoughts.

I can think of two possibilities to configure this:

• adding extension properties to the OpenAPI description and configure a mapping from the extension to an annotation.

Maybe like this

# mapping.yaml

map:
  extensions:
    x-custom-validation @ custom.annotation.Validation

or

• allow to configure annotations for object properties

map:
  object:
     SomeOpenApiObject:
         somePropertyOfTheObject @ custom.annotation.Validation

I guess the first would be nice to have that information in the api description. The second could be nice for implementation details.

[arvindand]

That's a good question...I think I would still prefer the first option because a feature like this would help in reusing custom property validations across beans and not associating with business logic of a specific type/model. And as you already mentioned, it keeps it part of the api spec.

Perhaps something like this,

properties:
exampleProp:
type: string
maxLength: 20
x-constraints:
- "capitalized"
- "isbn"

 mapping.yaml -->   
    
map:
  extensions:
    x-constraints:
      - "capitalized" => @custom.validation.Capitalized
      - "isbn" => @custom.validation.Isbn

[hauner]

yes, using list for multiple constraints makes sense :)

[hauner]

summarizing, it could work like this:

components:
  schemas:
    Foo:
      type: object
      properties:
        bar:
          type: string
          maxLength: 10
          x-constraints-1: "constraint"
          x-constraints-2:
            - "foo"
            - "bar"

and then map it to annotations with:

map:
  extensions:
    - x-constraints-1 @ some.custom.Constraint
    - x-constraints-2:
      - foo @ some.custom.FooConstraint
      - bar @ some.custom.BarConstraint

[arvindand]

Sounds good :)

[hauner]

openapi-processor/openapi-processor-base#92

[hauner]

released with 2024.1