在ASP.NET Core中查看模型和Fluent验证

Question

How can we Validate Models passed from Views to our API Controllers in ASP.NET Core. Is there a tool like FluentValidation or any similar approach that can be customized to return our errors and messages back to the client apps?

Answer 1

You make use of the IValidatableObject interface. Then create a abstract base class and let your classes inherit from it. You will need to add a reference to System.ComponentModel.DataAnnotations. You can add helper methods to the base class as well.

public abstract class ValidatingBase : IValidatableObject
{
        public bool IsNullOrEmpty(string property)
        {
            return string.IsNullOrEmpty(property);
        }

            #region IValidatableObject

        public abstract IEnumerable<ValidationResult> Validate(ValidationContext validationContext);

        public IEnumerable<ValidationResult> Validate()
        {
            var validationErrors = new List<ValidationResult>();
            var ctx = new ValidationContext(this, null, null);
            Validator.TryValidateObject(this, ctx, validationErrors, true);
            return validationErrors;
        }

        #endregion IValidatableObject
}

Then your class that inherits from the above

public class InsertCompanies : ValidatingBase
{
   public string CompanyName { get; set; }

   #region ValidatingCommandBase

        public override IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
        {
            if (this.IsNullOrEmpty(this.Name))
            {
                yield return new ValidationResult($"{nameof(this.Name)} field can't be null or empty.", new[] { nameof(this.Name) });
            }

            if (this.Name?.Length > 100)
            {
                yield return new ValidationResult($"{nameof(this.Name)} field can't be greater than 100 characters.", new[] { nameof(this.Name) });
            }
        }

        #endregion ValidatingCommandBase
}

There is not much limitation as to what you can do with the above implementation. Perhaps it is a viable option for you?

Asp.Net Core gladly will call the method for you, more information can be found at the link below. https://docs.asp.net/en/latest/mvc/models/validation.html

Answer 2

   [HttpPost]

    public ActionResult Register(RegisterViewModel model)
    {
  // if the validation doesn't match then load same view again with errors
        if (!ModelState.IsValid) 
        {
            return View(model);
        }



    }