Asp.Net core WebApi modelstate not working

Question

I have this webapi and trying to use the "modelstate.IsValid" function, but i have ran into some strange problem. I have the following method in my controller:

[HttpPut]
    [Route("{id}")]
    public async Task<IActionResult> Put([FromBody]ItemUpdateModel model, [FromRoute]int id)
    {
        if (!ModelState.IsValid) //Here i have a breakpoint!
        {
            return BadRequest(new
            {
                code = 400,
                message = ModelState.Values.First().Errors.First().ErrorMessage
            });
        }
}

And here is the model, ItemUpdateModel

using System.ComponentModel.DataAnnotations;

namespace TestApi.Models
{
    public class ItemUpdateModel
    {
        [Required]
        [Display(Name = "title")]
        [MaxLength(40)]
        public string Title { get; set; }

        [Required]
        [Display(Name = "discount")]
        public double Discount { get; set; }

        [Required]
        [Display(Name = "priceupdate")]
        public bool PriceUpdate { get; set; }
    }
}

I use Postman to send this http-request in the body with verb PUT and format json:

{ "title": "Some test", "discount": 0, "priceupdate": false }

This request should pass ok, but even if i try to leave out some properties the modelstate is always true. So when looking into the modelstate, this model aint binding at all to it. Only the [FromRoute]int id is bind, and the modelstate gets valid.

The model is anyway getting filled with data and working except from the modelstate validation/binding.

Also in the header im including: "application/json; charset=utf-8"

Anyone can help me with this, i have struggled a lot with this that seems like a really simple task :)

Thanks!

score 2 · Answer 1 · answered Apr 29 '17 at 11:08

2

Solved this, finally.

For some reason the modelstate aint dealing with the model if its "valid". And the model is getting valid by the JSON formatter adding the missing values for the datatypes double and int by adding value 0 or false for booleans. The solution was to make the properties nullable in the model, like

public double? Price { get; set; }

Now when i post the request, the price is NULL and presented in the modelstate as invalid.

answered Apr 29 '17 at 11:08

mike

143
2
8

check my other answer, if you want to deal with nullable `double` type, this is correct, if you want to use `double` without bein nullable you can use `[BindRequired]` for those types. – Bart Calixto Nov 17 '18 at 22:08

score 0 · Answer 2 · answered Nov 17 '18 at 22:06

0

You need to also use [BindRequired] if you want the properties to be required/exists on the payload.

answered Nov 17 '18 at 22:06

Bart Calixto

19,210
11
78
114

Where exactly do I place the `[BindRequired]` attribute – Swaleh Matongwa Aug 19 '20 at 20:56
1

Same places you use your [Required] attribute (on properties), or can be configured globally – Bart Calixto Aug 21 '20 at 14:29

Asp.Net core WebApi modelstate not working

2 Answers2