I got tired of describing the same request 3 times in Symfony

When building Symfony APIs, I kept duplicating the same request contract:

• validation rules in a DTO
• OpenAPI schema (often separately)
• mapping / glue code around it

After enough endpoints, the API layer started feeling heavier than the business logic.

Here’s a tiny example (validation in a DTO):

class CreateUserRequest
{
    #[Assert\NotBlank]
    #[Assert\Email]
    public string $email;
}

The same email then needs to exist again in OpenAPI docs - and the two drift over time.

So I built a small Symfony bundle to reduce that duplication.

Instead of describing the request multiple times, I keep a single JSON Schema:

{
  "type": "object",
  "required": ["email"],
  "properties": {
    "email": {
      "type": "string",
      "format": "email"
    }
  }
}

That schema becomes the source of truth for:

• request validation
• request mapping
• OpenAPI generation

Basic usage:

#[MapRequest('schemas/user-create.json')]
UserCreateDto $user

It's not trying to replace Symfony (or API Platform). The goal is to adopt it gradually and write less boilerplate while keeping request contracts explicit.

Project: https://github.com/outcomer/symfony-json-schema-validation
Docs: https://outcomer.github.io/symfony-json-schema-validation/

What part do you duplicate the most in Symfony APIs: validation, OpenAPI, or mapping?