ASP.NET Core REST Api - how to return multiple objects from GET method

Question

Hi,

I need to return multiple objects from GET method:

    [HttpGet]
    [ActionName("GetTimesheets")]
    [AllowAnonymous]
    public (List, Errors) GetTimesheets([FromBody] TimeSheetBO timeSheetBO)
    {
        (List ListTimesheetsTmp, Errors ErrorTmp) = TimesheetDAL.GetUserTimesheets(timeSheetBO);
        return (ListTimesheetsTmp, ErrorTmp);
    }

from Blazor page I cannot receive the correct values:

    var request = new HttpRequestMessage
    {
        Method = HttpMethod.Get,
        RequestUri = new Uri(@MySettings["URLTimeReportRestAPI"] + "/ControllerName/GetTimesheets"),
        Content = new StringContent(JsonConvert.SerializeObject(ObjTimeSheet), System.Text.Encoding.UTF8, "application/json"),

    };
    (var ListTimesheetsTmp, var ErrorTmp) = await http.SendJsonAsync<(List, Errors)>(request.Method, request.RequestUri.ToString(), ObjTimeSheet);

both objects (ListTimesheetsTmp, ErrorTmp) are NULL.

Any idea?

Best
Stefano

Accepted Answer

  for Asp.Net Core 2.1

The main result you failed to deserialize is you didn't return json object correctly.
You could create a combind object which contains ListTimesheetsTmp and ErrorTmp. And deserialize with the same Obj.

    public class Obj  
    {  
        public List listTimesheetsTmp;  
        public Errors errorTmp;  

        public Obj(List listTimesheetsTmp, Errors errorTmp)  
        {  
            this.listTimesheetsTmp = listTimesheetsTmp;  
            this.errorTmp = errorTmp;  
        }  
    }

Test
![78755-image.png

Answer

Hi,
first of all, thank you for your reply.

I have tested the procedure/service/controller several times, in different way (postman, trace log, ...) and I can say that:

thimesheetBO object is correctly valued. It contains the search criteria fields that the user has filled
TimesheetDAL.GetUserTimesheets function, returned correctly a list of timesheets (List) and the Error object, for testing purpose, has been filled with testing values (test messages) ... so, in the controller, the two objects are correctly filled

The problem is when they (two objects) are returned to the main call on the Blazor page, both contains null values

Thanks
Stefano

Answer

Hi, @Stefano Milanesi

Use Newtonsoft’s Json.NET instead of System.Text.Json. System.Text.Json is more strict than NewtonsoftJson.

How to replace?

Step 1. Install-Package Microsoft.AspNetCore.Mvc.NewtonsoftJson

Step 2. services.AddRazorPages().AddNewtonsoftJson();

Adding the AddNewtonsoftJson() call to the end means that we’re going to use the Newtonsoft.Json APIs over the default System.Text.Json implementation.

Then, change the codes of controller like below

        [HttpGet]  
        [ActionName("GetTimesheets")]  
        [AllowAnonymous]  
        public async Task GetTimesheets([FromBody] TimeSheetBO timeSheetBO)  
        {  
            (List ListTimesheetsTmp, Errors ErrorTmp) = TimesheetDAL.GetUserTimesheets(timeSheetBO);  
            return Json((ListTimesheetsTmp, ErrorTmp));  
        }

Test result

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Best Regards,
Michael Wang

Answer