.NET Core ModelState Validation after setting properties

Question

I've got a Web API controller in .NET Core. I'm posting data to save a new comment model, and I have the AuthorID property that has a [Required] data annotation on the model.

I'm setting the AuthorID in the controller before saving. However, ModelState is always coming back stating that AuthorID field is required.

How do I keep my validations on the model in place and validate correctly in this scenario?

public async Task<IActionResult> PostComment([FromBody] Comment comment)
{
    comment.AuthorID = Utilities.GetUserId(this.User);
    comment.CreatedAt = DateTime.Now;

    if (!ModelState.IsValid) {
        ....

Create a separate type for the incoming data that doesn't include the id https://learn.microsoft.com/en-us/aspnet/web-api/overview/data/using-web-api-with-entity-framework/part-5 — peco, Jan 15 '18 at 07:17

score 1 · Answer 1 · answered Jan 15 '18 at 21:01

-You can use TryValidateModel() but first you need to clear the model state and then revalidate the model again ASP.NET MVC TryValidateModel() Issues when Model is Modified

 public async Task<IActionResult> PostComment([FromBody] Comment comment)
    {

        comment.AuthorID = Utilities.GetUserId(this.User);
        comment.CreatedAt = DateTime.Now;

        ModelState.Clear();

        if (!TryValidateModel(comment)) // the same as !ModelState.IsValid
        {
            //Failure 
        }
        //Success 
    }

score 0 · Answer 2 · answered Jan 15 '18 at 06:40

0

You can remove ModelState validation using

ModelState.Remove("AuthorID")

answered Jan 15 '18 at 06:40

Riyaz K

11
2

Is there a way to do it and keep the validation? In this example AuthorID could be null, in which case I would like validation to fail. I could always write this separately, but ideally I'd like ModelState to validate with AuthorID, just after I've set it. – Ryan Jan 15 '18 at 06:51
Is your AuthorID Nullable in Model? – Riyaz K Jan 15 '18 at 07:03

score 0 · Answer 3 · answered Jan 15 '18 at 14:51

Create a ViewModel and pass it to your Controller Post

public async Task<IActionResult> PostComment([FromBody] CommentModel comment) 
{}

And about other logic that you need AuthorID, Create another ViewModel for that, Why you decide to depend only on one model for everything !!.

.NET Core ModelState Validation after setting properties

3 Answers3