CODEWITHSUNDEEP
c#jsonhttprequestblazorcrud
Martine Pirlet
Martine Pirlet

Reputation: 23

Blazor WASM : error while ReadFromJsonAsync <List<Object>> Post crud

I have this Error

The Json value could not be converted to System.Collections.Genereic.List 1[Blazor_fresh_project.Shared.Feedback]. Path: $ | LineNumber: 0 | BytePositionInLine: 1.

when I'm trying to CreateObj in this method :

public async Task<List<Feedback>> CreateFeedback(Feedback feedback)
        {
             var resulte = await _httpClient.PostAsJsonAsync($"api/feedback",feedback);
            string content = Newtonsoft.Json.JsonConvert.SerializeObject(resulte);
            Console.WriteLine("Here is THE CONTENT " +content);
             var   feedbacks = await resulte.Content.ReadFromJsonAsync<List<Feedback>>();
            return feedbacks;
        }

This error happen at line :

 var   feedbacks = await resulte.Content.ReadFromJsonAsync<List<Feedback>>();

The console write : Console debug
Do you have any suggestions or tips for debugging this kind of error?

Edit : api/feedback request

namespace Blazor_fresh_project.Server.Controllers
{

    [Route("api/[controller]")]
    [ApiController]
    public class FeedbackController : ControllerBase
    {
        List<Feedback> Feedbacks = new List<Feedback> {
           new Feedback{Id=1,Name="arthur",Description="I think this is great",DateOfPost=DateTime.Now,Power=10},
           new Feedback{Id=2,Name="Mario",Description=" coming soon",DateOfPost=DateTime.Now,Power=8},
           new Feedback{Id=3,Name="Chipolo",Description="I think this is great",DateOfPost=DateTime.Now,Power=17},
           new Feedback{Id=4,Name="Coco",Description=" coming soon",DateOfPost=DateTime.Now,Power=12},
           new Feedback{Id=5,Name="Marguerite",Description="I think this is great",DateOfPost=DateTime.Now,Power=6},
           new Feedback{Id=6,Name="Carine",Description=" coming soon",DateOfPost=DateTime.Now,Power=4}
            };
        [HttpGet]
        public async Task<IActionResult> GetFeedbacks()
        {
            return Ok(Feedbacks);
        }

        [HttpGet("{id}")]
        public async Task<IActionResult> GetSingleFeedback(int id)
        {
            var feedback = Feedbacks.FirstOrDefault(f => f.Id == id);
            if (feedback == null)
                return NotFound("this feedback wasn't found");
            
            return Ok(feedback);
        }
        [HttpPost]
        public async Task<IActionResult> CreateFeedback(Feedback feedback)
        {
            feedback.Id = Feedbacks.Max(h => h.Id + 1);
            Feedbacks.Add(feedback);
            return Ok(feedback);
        }
    }
}


namespace Blazor_fresh_project.Client.Services
{
    public class FeedbackService : IFeedbackService
    {
        private HttpClient _httpClient;
        public FeedbackService(HttpClient httpClient)
        {
            _httpClient = httpClient;
        }
        [Authorize]
        public async Task<List<Feedback>> GetFeedbacks()
        {
          return await _httpClient.GetFromJsonAsync<List<Feedback>>("api/feedback");

        }

        public async Task<Feedback> GetFeedback(int id)
        {
            return await _httpClient.GetFromJsonAsync<Feedback>($"api/feedback/{id}");
        }
        [Authorize]
        public async Task<List<Feedback>> CreateFeedback(Feedback feedback)
        {
             var resulte = await _httpClient.PostAsJsonAsync($"api/feedback",feedback);
            string content = Newtonsoft.Json.JsonConvert.SerializeObject(resulte);
            Console.WriteLine("Here is THE CONTENT " +content);
             var   feedbacks = await resulte.Content.ReadFromJsonAsync<List<Feedback>>();
            return  feedbacks;
        }
    }
}

Upvotes: 1

Views: 1022

Answers (1)

Henk Holterman
Henk Holterman

Reputation: 273464

The 'Console' screenshot shows us a payload of a single Feedback item, the request-in-a-browser shows a list of Feedbacks.

Your code is doing a POST, the browser does a GET. Apparently you have an endpoint with different return types for GET and POST.

Post the (relevant) code of your controller if you need more help.

OK, so indeed you have. You can change your controller or what looks more logical, your client:

    public async Task<Feedback> CreateFeedback(Feedback feedback)
    {
      var resulte = await _httpClient.PostAsJsonAsync($"api/feedback",feedback);
      var feedback = await resulte.Content.ReadFromJsonAsync<Feedback>();
      return feedback;
    }

and adapt the calling code accordingly.

Upvotes: 1

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