Graph.ArgumentValidator

Adds support for validating input arguments in HotChocolate

Generally, we use attributes from System.ComponentModel.DataAnnotations for validating our input models in controllers.

As HotChocolate doesn't validate input arguments, After installing this package, By just adding 2 lines of code in your Startup.cs file. You will be adding support for validation to all input models in your Queries/Mutations.

Installation Note:

Use Graph.ArgumentValidator v2.0.0 if you are using HotChocolate v12.

Use Graph.ArgumentValidator v1.0.1 if you are using HotChocolate v11.

Tech Note: You can use all validation attributes/rules from System.ComponentModel.DataAnnotations (ex: Required, MinLength, Regex etc). This package just adds a middleware to the hot chocolate resolver for validating your input models as configured in the below steps.

Steps for configuring validator

Step 1

Go to StartUp.cs file and inside ConfigureServices make the following changes.

Step 2

Add argument validator to services by referring to below code

services
  .AddGraphQLServer()
  .AddArgumentValidator();

Step 3

Just add the Validatable attribute to all the classes you defined for input.

Ex:

    using System.ComponentModel.DataAnnotations;
    using Graph.ArgumentValidator;
    
    namespace Demo
    {
        [Validatable]
        public class RegisterUserInput
        {
            [Required, MinLength(4, ErrorMessage = "Username must be atleast 4 characters.")]
            public string UserName { get; set; }

            [Required, EmailAddress(ErrorMessage = "Email Id format is invalid.")]
            public string Email { get; set; }

            [Required, RegularExpression(@"^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}$", ErrorMessage = "Password needs to be more strong.")]
            public string Password { get; set; }
            
            [Compare(nameof(Password), ErrorMessage = "Passwords do not match!")]
            public string ConfirmPassword { get; set; }
        }
        
        public class UserMutations
        {
            public int RegisterUser(RegisterUserInput input, [Service] UserService userService)
            {
                return userService.RegisterUser(input);
            }
        }
    }

Another way of providing inline validation for Primitive data types

  using System.ComponentModel.DataAnnotations;
  using Graph.ArgumentValidator;
  
  namespace Demo
  {
      public class Mutations
      {
          public bool RegisterUserPhone([Required(ErrorMessage = "Email is required")string email,
              [Phone(ErrorMessage = "Invalid Phone Number")] string phone)
          {
              return userService.RegisterUserPhone(email,phone);
          }
      }
  }

When the user is given the following wrong values to the mutation input

     mutation{
      registerUser(input:{userName:"va2", password:"weak", confirmPassword:"strong", email:"varun"})
     }

This is the response we got from GraphQL Server

{
  "errors": [
    {
      "message": "Username must be atleast 4 characters.",
      "path": [
        "input"
      ],
      "extensions": {
        "field": "userName"
      }
    },
    {
      "message": "Email Id format is invalid.",
      "path": [
        "input"
      ],
      "extensions": {
        "field": "email"
      }
    },
    {
      "message": "Password needs to be more strong.",
      "path": [
        "input"
      ],
      "extensions": {
        "field": "password"
      }
    },
    {
      "message": "Passwords do not match!",
      "path": [
        "input"
      ],
      "extensions": {
        "field": "confirmPassword"
      }
    }
  ]
}