Bad Request When Using PostAsJsonAsync C#

Question

I am trying to Post a model to my MongoDB, but my Blazor app's post command does not even reach my API's Post method in the Controller. I've seen some topics about this and also tried to debug this issue for hours.

I am trying to post a really simple model.

public string MomentCategoryName { get; set; }

The button click activates this method. (I hardcoded a CategoryName for this one.)

public async Task PostAsync(MomentCategoryModel momentCategory)
        {
            using (HttpResponseMessage response = await _api.ApiClient.PostAsJsonAsync("api/MomentCategory/Create", momentCategory))
            {
                if (!response.IsSuccessStatusCode)
                {
                    throw new Exception();
                }
            }
        }

The baseuri and the client is initialized in another class, but the whole uri will look like this: https://localhost:7141/api/MomentCategory/Create

The PostMomentCategory in the MomentCategoryController gets a MomentCategoryModel from another library:

[BsonId]
[BsonRepresentation(MongoDB.Bson.BsonType.ObjectId)]
public string Id { get; set; }
public string MomentCategoryName { get; set; }

And then in the this code should run, but the compiler never gets to this, it never runs:

[HttpPost]
[Route("Create")]
public void PostMomentCategory(MomentCategoryModel model)
{
    _momentCategoryData.CreateMomentCategory(model);
}

Because of that I get back a Bad Request. But when I do a GET request that almost the same, it runs correctly. Example:

public async Task<List<MomentCategoryModel>> GetAllAsync()
        {
            using (HttpResponseMessage response = await _api.ApiClient.GetAsync("api/MomentCategory/GetAll"))
            {
                if (response.IsSuccessStatusCode)
                {
                    var result = await response.Content.ReadFromJsonAsync<List<MomentCategoryModel>>();
                    return result;
                }
                else
                {
                    throw new Exception();
                }
            }
        }

Thank you for your help and your time in advance!

Answer 1

In MomentCategoryController I adjusted the Post method as the following:

[HttpPost]
[Route("Create")]
[Consumes("application/x-www-form-urlencoded")]
public void PostMomentCategory([FromForm] TestMCategoryModel model)
{
    _momentCategoryData.CreateMomentCategory(model);
}

In public async Task PostAsync(MomentCategoryModel momentCategory) method I added a list of KeyValuePair with one element. And also added an HttpContent like this: HttpContent httpcontet = new FormUrlEncodedContent();

This way it works, I get an OK code back (Status code 200). Maybe it would work with the suggested string content if I adjust what the API should consume. I will do a test with that as well, but right now it works this way.

I would like to thank everyone who took the time to read thru the issue and suggest a possible solution!