Blazor Server Side against Net5 WebAPI - GetFromJsonAsync returns unexpected null

Question

User379720387 posted

This is a continuation of https://forums.asp.net/t/2174005.aspx?One+to+many+projection+in+a+Web+API+NET5+0+controller+how+to+do+it+

In the above thread the end result was that the API call was successfully returned in Swagger.

Now I am at the point where I need to present the results in Blazor Server page

records returns null, however using swagger I can see that parameters 22, 54 and 2 (hard coded below), returns two records, all fields have values.

With a breakpoint at return recordDetails at the end of this controller action I can see the same data that Swagger sees.

recordDetails
Count = 2
    [0]: {BtApiEf5.Model.Custom.RecordDetail}
    [1]: {BtApiEf5.Model.Custom.RecordDetail}
recordDetails[0]
{BtApiEf5.Model.Custom.RecordDetail}
    BDate: "Jan 24 2021 11:09PM"
    CName: "cname1"
    Initials: "JMC"
    IsBilled: false
    IsPaid: false
    ServiceItems: Count = 1
    SvcLevel: "R2"
    TDate: "Jan 24 2021 11:04PM"
    TransactionId: 1033
recordDetails[0].ServiceItems
Count = 1
    [0]: {BtApiEf5.Model.Custom.ServiceItem}
recordDetails[0].ServiceItems[0]
{BtApiEf5.Model.Custom.ServiceItem}
    BilledRate: 55.0000
    MainCat: "primary"
    ServiceId: 1025
    ServiceName: "service1 long"
    shortForm: "service1 short"

private IEnumerable<RecordDetail> records;

protected override async Task OnInitializedAsync(). 
    {
        try
        {
            var httpClient = _clientFactory.CreateClient("ServerAPI");
            httpClient.DefaultRequestHeaders.Add("Accept", "application/json")
            records = await httpClient.GetFromJsonAsync<RecordDetail[]>($"{baseUrl}/api/Record/DetailByClient/22/54/2");           
        }
        catch (Exception ex) { Console.WriteLine(ex.Message); }                
    }

Swagger even tells me this is the url for this controller action:

https://localhost:44384/api/Record/DetailByClient/22/54/2

What am I missing here?

Answer 1

User379720387 posted

private IEnumerable<RecordDetail> recordDetails = new List<RecordDetail>();

That is what it took, to get the data.

This made my code run however it turns out that json data from the controller was not being populated.

A Microsoft engineer (Ignite one-on-one consultation) has suggested a potential race condition and a remedy.

His suggestion was to separate the data retrieval (controller) from the serialization. And this code is below.

I can report now that data now shows what I was hoping to see in the first place. 

However, the Deserialize statement now has a squiggle with a complaint about round hole, square peg:

Cannot implicitly convert type System.Collections.Generic.List.Model.RecordGrid to Model.RecordGrid

var httpClient = _clientFactory.CreateClient("ServerAPI");
            httpClient.DefaultRequestHeaders.Add("Accept", "application/json");

            var json = JsonSerializer.Serialize(records);
            //var y = JsonSerializer.Deserialize<Service>(json);
            var content = new StringContent(json);
            string errorMessage = null;
        
            content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/json");
            var response = await httpClient.GetAsync($"{baseUrl}/api/Record/ByProvider/22");
            var data = await response.Content.ReadAsStringAsync();
            RecordGrid result = new RecordGrid();


            //snackMsg = String.Format("{0} records retrieved", records.Count());

            if (response.IsSuccessStatusCode)
            {
                result = JsonSerializer.Deserialize<List<RecordGrid>>(data);
            }
            else
            {
                errorMessage = data;
            }

I suspect my problem lies here, but dont know how to remedy that.

And here is RecordGrid:

public class RecordGrid
    {
        
        public int ClientId { get; set; }
        
        public int ProviderId { get; set; }
        public string CName { get; set; }

        public string Location { get; set; }

        public string State { get; set; }

        public string OName { get; set; }

        public int TxnCount { get; set; }
    }