Enum Validation

kiln validates string columns against a set of allowed values, generating oneof= validation tags.

Auto-Detection

If your schema uses CHECK constraints, kiln detects allowed values automatically:

CREATE TABLE posts (
  status TEXT NOT NULL DEFAULT 'draft'
    CHECK (status IN ('draft', 'published', 'archived'))
);

This generates:

type CreatePostRequest struct {
    Status string `json:"status" validate:"required,oneof=draft published archived"`
}

No config needed.

Config Override

For columns without CHECK constraints, specify values in kiln.yaml:

overrides:
  users:
    enums:
      role: [member, moderator, admin]
  posts:
    enums:
      status: [draft, published, archived]

Config values always take precedence over auto-detected constraints.

Error Response

Invalid values return a structured error:

curl -X POST http://localhost:8080/api/v1/users \
  -H "Content-Type: application/json" \
  -d '{"email": "[email protected]", "name": "Test", "role": "superadmin"}'

{
  "error": "validation failed",
  "fields": {
    "role": "must be one of: member moderator admin"
  }
}

Update Requests

On PATCH requests, enum fields are optional but still validated when provided:

type UpdatePostRequest struct {
    Status *string `json:"status,omitempty" validate:"omitempty,oneof=draft published archived"`
}

Omitting the field is fine. Sending an invalid value is rejected.