Constraints for validation

[patrick-fitzgerald]

Hi, Is it currently possible to use constraints for validation, or does it require a plugin? This would be a nice feature to have. e.g

type SignUpInput {
  email: String! @constraint(format: "email", maxLength: 255)
  password: String! @constraint(maxLength: 255)
  firstName: String! @constraint(pattern: "^[0-9a-zA-Z]*$", maxLength: 255)
  lastName: String! @constraint(pattern: "^[0-9a-zA-Z]*$", maxLength: 255)
}

https://blog.apollographql.com/graphql-validation-using-directives-4908fd5c1055

[vektah]

Will be addressed via plugins - #228

[ravilution]

Hi @vektah

I was able to achieve the constraint directive with the code below. However, I also want to sanitize my input values. How can I change the obj value that goes to the resolver inside the directive? For example, how can I change the input that comes into lowercase?

func ConstraintDirective(ctx context.Context, obj interface{}, next graphql.Resolver, pattern string, max int, min int, isLower bool) (res interface{}, err error) {
	v := obj.(string)
	r := regexp.MustCompile(pattern)

	if !r.MatchString(v) || len(v) < min || len(v) > max {
		return nil, gqlerror.Errorf("format")
	}

	return next(ctx)
}

Also is there a way to get the graphql input attribute name inside the directive?