I have a .NET 8 Blazor WebApp project with a separate WebAssembly project for the front end. When I call the api and return a list of objects, it shows a count of 0, yet actually contains elements. It shows both in Rider’s debugging value watches and when I am looking at List.Count value in code. In postman the json that the api is returning is formatted correctly, so I think it’s something to do with the deserialization on the WebAssembly side. But have no idea what I’m doing wrong.

   public async Task<ApiResponse<List<TreatmentDto>>> GetTreatmentsAsync()
   {
        var response = await httpClient.GetAsync("api/treatments");
        return await response.HandleResponse<List<TreatmentDto>>();
   }

    public static async Task<ApiResponse<T>> HandleResponse<T>(this HttpResponseMessage response)
    {
        if (response.IsSuccessStatusCode)
        {
            return await response.Content.ReadFromJsonAsync<ApiResponse<T>>() ?? new ApiResponse<T> { Success = false };
        }
        return new ApiResponse<T> { Success = false, Message = "API call failed", Errors = new List<string> { response.ReasonPhrase } };
    }

    public class ApiResponse<T>
    {
        public bool Success { get; set; }
        public T Data { get; set; }
        public string Message { get; set; }
        public List<string> Errors { get; set; } = new List<string>();
    }

Postman response

{
    "success": true,
    "data": [
        {
            "id": "2f312b5f-6d6f-4615-8bf1-b7b88bc40365",
            "type": 0,
            "name": "HYDROCORTISONE 10 MG ORAL TABLET [CORTEF]",
            "description": "asdfasf",
            "isMuted": false,
            "customerNotes": "",
            "medicationRxcui": 208712,
            "medicationRxstring": "HYDROCORTISONE 10 MG ORAL TABLET [CORTEF]",
            "tzid": "",
            "expectedUnits": [
                {
                    "id": "dab0842c-226d-4c49-8b8c-8f1ba0766086",
                    "treatmentId": "2f312b5f-6d6f-4615-8bf1-b7b88bc40365",
                    "numberOfUnits": 2,
                    "unitType": "Pills",
                    "order": 0
                }
            ],
            "reminders": [
                {
                    "id": "84699631-db01-4e09-b292-6c26f5c4236d",
                    "rRule": "FREQ=WEEKLY",
                    "startDate": "2024-09-08T10:00:00-04:00",
                    "endDate": null,
                    "untilDate": null,
                    "tzid": "",
                    "treatmentId": "2f312b5f-6d6f-4615-8bf1-b7b88bc40365"
                },
                {
                    "id": "a77dfbe2-5290-4453-99af-9c7ac3dbe5b7",
                    "rRule": "FREQ=WEEKLY",
                    "startDate": "2024-09-08T09:00:00-04:00",
                    "endDate": null,
                    "untilDate": null,
                    "tzid": "",
                    "treatmentId": "2f312b5f-6d6f-4615-8bf1-b7b88bc40365"
                }
            ]
        }
    ],
    "message": null,
    "errors": []
}

Relevent Client Program.cs services

builder.Services.AddScoped(sp => new HttpClient
    { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
builder.Services.AddScoped<ITreatmentService, TreatmentService>();