Can't send via POST a nested JSON with null Subclass Net Core API

Question

I want to send an object with subobjects as Json to my Net Core API using c#. This works if the sub-objects are filled. But as soon as the sub-object is null, it doesn't arrive at the controller. I received an error with status code 400.

    StatusCode: 400, ReasonPhrase: 'Bad Request', Version: 1.1, Content: System.Net.Http.StreamContent, Headers:{  Date: Thu, 10 Mar 2022 09:40:25 GMT Server: Kestrel Content Length: 296 Content-Type: application/problem+json; charset=utf-8 }}

I've been googling and trying a lot for the past 2 days. but unfortunately nothing works.

This is my model

   public class Location
   {
        [Key]
        public string Zipcode{ get; set; }
        public string LocationName { get; set; }
        public DateTime CreationDate{ get; set; }

        [ForeignKey("Street")]
        public string StreetID{ get; set; }
        public virtual Street Street{ get; set; }
    }

    public class Street
    {
        [Key]
        public string StreetName { get; set; }
    }

This is my Reqeust

            HttpClient httpClient = new HttpClient();
            string requestUri = "https://localhost:5001/Customers/CreateLocation";
            
            var json = JsonConvert.SerializeObject(location);
            var buffer = System.Text.Encoding.UTF8.GetBytes(json);
            var byteContent = new ByteArrayContent(buffer);
            byteContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
            var response = await httpClient.PostAsync(requestUri, byteContent);
            string result = response.Content.ReadAsStringAsync().Result;

This is my Controller

        [HttpPost]
        [Route("CreateLocation")]
        public IActionResult CreateOrt(Location location)
        {
            location = KundenRepositorie.CreateLocation(Bankdaten_DB, location);
            return CreatedAtAction("GetCustomerByID", new { id = location.Zipcode}, location);
        }

I have already added the following to Programm.cs

builder.Services.AddControllers().AddNewtonsoftJson();
builder.Services.AddControllers().AddJsonOptions(options =>
{
   options.JsonSerializerOptions.DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull;
});

This Json Works fine and arrives at the controller

{"Zipcode":"89898",
 "LocationName ":"MyCity",
 "CreationDate":"2022-03-10T11:01:25.9840573+01:00",
 "StreedID":"Am Dorf",
 "Street":
          {"StreetName ":"Am Dorf",
            "Kunden":null}
}

But here I get the error message and it doesn't arrive

{"Zipcode":"89898",
    "LocationName":"MyCity",
    "CreationDate":"2022-03-10T11:12:39.8402702+01:00",
    "StreedID":null,
    "Street":null}

I am very grateful for any help tip. Maybe I'm doing something fundamentally wrong. I'm here learning for myself and experimenting with the API and the database model to gain experience.

Answer 1

since you are using net 6 , you have to make everything nullable, this is why you have the error you can try this

public class Location
   {
        .....
        public string? StreetID{ get; set; }
        public virtual Street? Street{ get; set; }
    }

but I recommend you to fix everything, by removing nullable from your project properties, otherwise it will be repeating and repeating

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

then fix the program, you added controllers twice, it should be once

builder.Services.AddControllers()
.AddNewtonsoftJson(options =>
  options.SerializerSettings.ContractResolver =
        new CamelCasePropertyNamesContractResolver());

then fix your http request , you don't need any byte array, since you are sending json

    string requestUri = "https://localhost:5001/Customers/CreateLocation";
using HttpClient client = new HttpClient();

client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

 var json = JsonConvert.SerializeObject(location);
var content = new StringContent(json, UTF8Encoding.UTF8, "application/json");    
  
var response = await client.PostAsync(requestUri, content);     

if (response.IsSuccessStatusCode)
    {
        var stringData = await response.Content.ReadAsStringAsync();
        var result = JsonConvert.DeserializeObject<object>(stringData);
    }   

and fix the post action

         [HttpPost]
        [Route("CreateLocation")]
        public IActionResult CreateOrt([FromBody] Location location)