Trying to avoid creating separate DTOs for my one really simple post in this app. I have a required property on my entity that is a reference to another entity. This is the user, which is grabbed later by the authentication/authorization and populated.

Except... I can't get past the instantiation in the controller because it's a non-nullable property.

public class MyModel {
    public UserModel User { get; set; } = null!;
}

public IActionResult Submit(MyModel model){
    model.User = CurrentUser; // <- can't get here.
}

0: "The User field is required."

I was under the impression that the = null! would allow the model to instantiate and not care that it's "null" until I try to utilize it later? I may be misunderstanding that functionality significantly.

I'd very much like to:

• Keep this property not-nullable.
• Not have to create a second class to handle post data without this property

Is this possible?

CodePudding user response：

You would need to initialize the property to some valid value. The point of non-nullable is that it can never be null.

My only suggestions would be to either

1. let the value be null, and initialize as such, but edit set operator to throw ArgumentNullException if given null value later,
2. define User.Null to be a non-existent User, used for "initialization", or
3. change your class to enable passing value to UserModel during initialization and create MyModel in Submit as output parameter.

CodePudding user response：

You can work with a default value.

If the instance you are receiving is null, it will create a new instance of User, else it will contain your non-null instance.

public class MyModel {
    public UserModel User { get; set; } = new User();
}

CodePudding user response：

What if you use a property with a backing field?

public class MyModel {

    [CanBeNull]
    private UserModel _User = null;

    public UserModel User 
    { 
        get { return _User ?? throw new System.InvalidOperationException("_User is has not been set yet"); }
        set { _User = value; }
    }
}

CodePudding user response：

You are probably using Net 6. You can remove option nullable from project configuration. This way you don't need to do a stupid job to mark all default nullabble properties all your classes as nullable

<PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <Nullable>disable</Nullable>   <!-- change from enable -->
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>