Asp.Net Core Web Api, Json Object not return child objects in Complex object

Question

I have Asp.Net core 3.1 Web Api where a complex object sould be returned by an action like a Json, the problem is that the returned object does not contain the list of child objects:

Below the object:

public class DepartementViewModel
{
    public int Dep_ID { get; set; }
    public string Dep_Name { get; set; }

    public List<BasicEmpViewModel> listEmployees = new List<BasicEmpViewModel>();
}

And the Action

[HttpGet]
public async Task<ActionResult<IEnumerable<DepartementViewModel>>> GetDepartement()
{
    IRepository IRepos = new DepartementRepository(_context);
    IList<DepartementViewModel> ilIst = await IRepos.GetList();
    return Ok(ilIst);
}

The repository GetList function

public async Task<IList<DepartementViewModel>> GetList()
{
    IList<DepartementViewModel> listDept = new List<DepartementViewModel>();
    listDept = await(from dept in _context.Departement                        
                          orderby dept.Dep_ID ascending
                              select new DepartementViewModel
                              {
                                  dept.Dep_ID ,
                                  dept.Dep_Name
                              }
                     ).ToListAsync();

    listDept.ForEach(x =>
    {       
        var emObj =_context.Employee;
        foreach (Employee E in emObj)
        {
            E.listEmployees.Add(new BasicEmpViewModel()
                                    {
                                        Emp_ID = E.Emp_ID,
                                        Emp_Name = E.Emp_Name,
                                        Checked = (E.Dep_ID == x.Dep_ID) ? true : false
                                    }
                                );
        }
    }); 

    return listDept;
}

The returned Json object does not contain the list of employees "listEmployees", it just displays information relating to the main object :Dep_ID and Dep_Name.

Is there something missing in my code ?.

Thank you

Do you use EF? Did you forget Include employees at method which retrieve data? learn.microsoft.com/en-us/ef/core/querying/related-data — Sergey Nazarov
– Sergey Nazarov, Commented Oct 5, 2020 at 12:55
I didn't use include but I used Linq requests to populate the object and the object is well populated but it doesn't show the list "listEmployees " in the Json object — devjelop anje
– devjelop anje, Commented Oct 5, 2020 at 13:27
Can you debug and see if "ilist" contains any employess before converting to json? — Tan
– Tan, Commented Oct 6, 2020 at 6:47

devjelop anje · Accepted Answer · 2020-10-06 10:08:10Z

8

I have found the solution, I publish the solution for any such problem. indeed it is necessary to put a Getter and Setter for the property listEmployees in the class DepartementViewModel like below

public class DepartementViewModel
{
    public int Dep_ID { get; set; }
    public string Dep_Name { get; set; }

    public List<BasicEmpViewModel> listEmployees {get; set; };
}

Cordially

answered Oct 6, 2020 at 10:08

devjelop anje

1991 silver badge8 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Joseph L. Over a year ago

This should be the Accepted answer here. Thanks!

Zhi Lv · Accepted Answer · 2020-10-06 06:44:40Z

4

I suppose perhaps you are using System.Text.Json library to serialize and deserialize data in the .net core application, right? If that is the case, perhaps the issue is related this library. As far as I know, when we using the System.Text.Json library to serialize complex object, it will only return the outer object (without the inner entities).

To solve this issue, you could try to use the Microsoft.AspNetCore.Mvc.NewtonsoftJson library to serialize data. Refer the following steps:

Install Microsoft.AspNetCore.Mvc.NewtonsoftJson package via Nuget.

Register the NewtonsoftJson in the Startup.ConfigureServices method:

     services.AddControllersWithViews().AddNewtonsoftJson();

Here are some related articles about the System.Text.Json and Microsoft.AspNetCore.Mvc.NewtonsoftJson, you could refer them:

How to serialize and deserialize (marshal and unmarshal) JSON in .NET

How to migrate from Newtonsoft.Json to System.Text.Json

answered Oct 6, 2020 at 6:44

Zhi Lv

22.2k1 gold badge28 silver badges37 bronze badges

4 Comments

devjelop anje Over a year ago

I changed the method with the use System.Text.Json but the problem still persists, the list listEmployees is not returned in the Json object below the code:

devjelop anje Over a year ago

var options = new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase, WriteIndented = true }; IList<DepartementViewModel> ilIst = await IRepos.GetList(); var modelJson = JsonSerializer.Serialize(ilIst, options); return Ok(modelJson);

Zhi Lv Over a year ago

Yes, I know that. I have created a sample based on your code and reproduced the problem. If I use the System.Text.Json, it will show this issue. After changing the to use the Microsoft.AspNetCore.Mvc.NewtonsoftJson library, everything works well. So, I suggest you try to use the Microsoft.AspNetCore.Mvc.NewtonsoftJson library, instead of 'System.Text.Json'.

devjelop anje Over a year ago

I get the solution, i should put the Getter and setter for listEmployees property

Jules Amonith · Accepted Answer · 2020-10-27 00:07:35Z

3

Took some digging to find, but your issue is that listEmployees is a field. Currently, System.Text.Json only supports the serialization of properties. You'll need to either change listEmployees to a property or use Newtonsoft.Json.

Jules Amonith

314 bronze badges

Collectives™ on Stack Overflow

Asp.Net Core Web Api, Json Object not return child objects in Complex object

3 Answers 3

1 Comment

4 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related