Validate only few properties of a model class using Data Annotations from a Console application in c#

Question

I have a model class with several properties like below and each property have Data Annotations for the validation

Class User{

[Required]
public string First Name{get;set;}

[Required]
public string Last Name {get;set;}

[Required, EmailAddress, MaxLength(256), Display(Name = "Email Address")]
public string Email {get;set;}

[Required, MaxLength(20), DataType(DataType.Password), Display(Name ="Password")]
public string Pasword {get;set;}
}

Now, in the Console app I ask user to give me an email address and password to Login. How can I validate if a given email and password satify the conditions. Since it is login, I dont want to validate First Name and Last Name

var context = new ValidationContext(user);
var results = new List<ValidationResult>();

var isValid = Validator.TryValidateObject(user, context, results, true);

TryValidateObject takes an instance as a first parameter, so when I do this it also returns me error for First Name and Last Name

Can someone please suggest how can I validate only Email and password using the same User class?

DavidG · Accepted Answer · 2018-12-30 23:39:29Z

1

If you have a different part of the app that requires a different set or properties and validation rules, then you should be using a completely distinct model for that purpose. So you could have a new model like this:

public class UserCredentials
{
    [Required, EmailAddress, MaxLength(256), Display(Name = "Email Address")]
    public string Email {get;set;}

    [Required, MaxLength(20), DataType(DataType.Password), Display(Name ="Password")]
    public string Password {get;set;}
}

Now your code that looks something like this will work:

UserCredentials userCredentials = .... //Get the credentials from somewhere

var context = new ValidationContext(userCredentials);
var results = new List<ValidationResult>();

var isValid = Validator.TryValidateObject(userCredentials, context, results, true);

Also, if you want to share this code with the user class, you could make use of inheritance:

public class User : UserCredentials
{
    [Required]
    public string FirstName{ get; set; }

    [Required]
    public string LastName { get; set; }
}

answered Dec 30, 2018 at 23:39

DavidG

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1 Comment

Robin Over a year ago

Hi David, Thank you for the quick reply! One more question : Now when I validate against User class, it first validates FirstName, LastName and then properties of UserCredentials. Is there any way we can change the order as we want?

John Babb · Accepted Answer · 2018-12-30 23:40:19Z

1

I would split the class up into a base class for the user name and password and the create a class off of it to hold the user name and password.

Something like this:

Class User : AuthUser {

    [Required]
    public string First Name{get;set;}

    [Required]
    public string Last Name {get;set;}

}

Class AuthUser {
    [Required, EmailAddress, MaxLength(256), Display(Name = "Email Address")]
    public string Email {get;set;}

    [Required, MaxLength(20), DataType(DataType.Password), Display(Name ="Password")]
    public string Pasword {get;set;}
}

answered Dec 30, 2018 at 23:40

John Babb

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