convert WebApi response from c# object to JSON

Question

i need help to get data from web Api. I use EF with two tables named "Reichweites" and "Points"(child)

This is my DTO class:

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web;

namespace xms_ef_vers1.Models
{
    public class ReichweitePointsDto
    {

        public ReichweitePointsDto() { }

        public ReichweitePointsDto(Reichweite reichweite)
        {
            ReichweiteID = reichweite.Id;
            Name = reichweite.Name;
            Potenzial = reichweite.Potenzial;
            Geschlecht = reichweite.Geschlecht;
            CPGRP = reichweite.CpGRP;
            ZielGRP = reichweite.ZielGRP;
            Benutzer = reichweite.Benutzer;

            PointListe = new List<PointListDto>();
            foreach (Points item in reichweite.PointListe)
            {
                PointListe.Add(new PointListDto(item));
            }
        }

        [Key]
        public int ReichweiteID { get; set; }
        public string Name { get; set; }
        //[Required]
        public int Potenzial { get; set; }
        //[Required]
        public string Geschlecht { get; set; }
        //[Required]
        public int CPGRP { get; set; }
        public int ZielGRP { get; set; }
        public string Benutzer { get; set; }

        public virtual List<PointListDto> PointListe { get; set; }

        public Reichweite ToEntity()
        {
            Reichweite reich = new Reichweite
            {
                Id = ReichweiteID,
                Name = Name,
                Potenzial = Potenzial,
                Geschlecht = Geschlecht,
                CpGRP = CPGRP,
                ZielGRP = ZielGRP,
                Benutzer = Benutzer,
                PointListe = new List<Points>()
            };

            foreach (PointListDto item in PointListe)
            {
                reich.PointListe.Add(item.ToEntity());
            }

            return reich;
        }

    }
}

And my Data Model:

1:n relation

Main Table is Reichweites

Id
Name
Potenzial
Geschlecht
CpGRP
ZielGRP
Benutzer

Child Table is Points

Id
GRP
RW_TV
Cost_TV
Rw_ZuWGS
Cost_I_Rea
ReichweiteId fk

I want provide the data in this format:

[   
  {
    "User":"testuser",
    "CPGRP":21321321,   
    "Sex":"men",    
    "Name": "test",
    "Potenzial":213213,
    "ReichweiteID":0,   
    "ZielGRP": 21321321 
    "PointList":[
                      {
                       "Cost_I_Rea":"22202771.01",
                       "Cost_TV":"213213210.0" ,
                       "GRP":10,   
                       "ID":0, 
                       "ReichweiteID_F":1, 
                       "RW_TV":"9.603",    
                       "RW_Zuwgs":"9.603",
                      },
                      {
                        "Cost_I_Rea":"22202771.01",
                        "Cost_TV":"213213210.0" ,
                        "GRP":10,   
                        "ID":0, 
                        "ReichweiteID_F":1, 
                        "RW_TV":"9.61103",  
                        "RW_Zuwgs":"9.6043",
                      },
                      {
                        "Cost_I_Rea":"22202771.01",
                        "Cost_TV":"213213210.0" ,
                        "GRP":10,   
                        "ID":0, 
                        "ReichweiteID_F":1, 
                        "RW_TV":"9.61103",  
                        "RW_Zuwgs":"9.6043",
                      },
                      {
                        "Cost_I_Rea":"22202771.01",
                        "Cost_TV":"213213210.0" ,
                        "GRP":10,   
                        "ID":0, 
                        "ReichweiteID_F":1, 
                        "RW_TV":"9.61103",  
                        "RW_Zuwgs":"9.6043",
                      }
              ]
   }
]

some additional requirement is that i must fiter by id and user name.

This is how i try it now but it do not work.

What do you need to understand my question better?

[ResponseType(typeof(Reichweite1Dto))]

public async Task<IHttpActionResult> GetReichweite(int id)
{
    var reich = await db.Points.Include(b => b.ReichweiteId)
        .Select(b => 
        new ReichweitePointsDto ()
        {
            Benutzer = b.Reichweite.Benutzer,
            Name = b.Reichweite.Name,
            Geschlecht = b.Reichweite.Geschlecht,
            CPGRP = b.Reichweite.CpGRP,
            Potenzial = b.Reichweite.Potenzial,
            ZielGRP = b.Reichweite.ZielGRP,
            PointListe = (from item in reich
                          select new Points()
                              {
                                  GRP = item.GRP,
                                  RW_TV = item.RW_TV,
                                  Cost_TV = item.Cost_TV,
                                  Rw_ZuWGS = item.RW_Zuwgs,
                                  Cost_I_Rea = item.Cost_I_Rea,
                              }).ToList()
          };
      return reich;
}

I don't understand the question , what exactly are you have trouble with? once you have filled the models with data all you have to do is in the controller this.Json(reich); and it will turn c# objects into JSON like that for you — Scott Selby
– Scott Selby, Commented Oct 27, 2014 at 13:29
I don´t know how i have to write the get method that i get the data like the json example — Andreas Klumpe
– Andreas Klumpe, Commented Oct 27, 2014 at 13:34
What I meant was , are you already properly returning all the data in c# objects? and just need it converted to JSON? — Scott Selby
– Scott Selby, Commented Oct 27, 2014 at 13:58
so , you are already getting the data just fine?? and are having problems converting into JSON? — Scott Selby
– Scott Selby, Commented Oct 27, 2014 at 14:09

Andreas Klumpe · Accepted Answer · 2014-10-28 10:35:53Z

Yes i have it. The key was to keep it simple. Many thanks to Scott.

Now my method works fine and provides the data in the Json format which i wanted!

Here the Methods:

    namespace xms_ef_vers1.Controllers
    {
        public class TVKurveController : ApiController
        {
            private ReichweitenKurveContext db = new ReichweitenKurveContext();


            // GET api/TVKurve/5
            public IHttpActionResult GetReichweite(int id)
            {
                var obj = db.Reichweites.Where(r => r.Id == id && r.Benutzer == user.identity.name);
                return Ok(obj);
            }

            /////////////////////
            // GET api/TVKurve
            [ResponseType(typeof(ReichweitePointsDto))]

            public IEnumerable<Reichweite> GetReichweite()
            {
                var obj = db.Reichweites.Take(100);
                return obj;
            }
         }
   }

Someone was missing in the WebApiConfig.cs:

var json = config.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling =
Newtonsoft.Json.PreserveReferencesHandling.Objects;

config.Formatters.Remove(config.Formatters.XmlFormatter);

And here how the result will be:

[
    {
        "$id": "1",
        "PointListe": [
            {
                "$id": "2",
                "Reichweite": {
                    "$ref": "1"
                },
                "Id": 2771,
                "GRP": 10,
                "RW_TV": 1000,
                "Cost_TV": 15600,
                "Rw_ZuWGS": 1000,
                "Cost_I_Rea": 15.6,
                "ReichweiteId": 21
            },
            {
                "$id": "3",
                "Reichweite": {
                    "$ref": "1"
                },
                "Id": 2772,
                "GRP": 20,
                "RW_TV": 2000,
                "Cost_TV": 31200,
                "Rw_ZuWGS": 1000,
                "Cost_I_Rea": 15.6,
                "ReichweiteId": 21
            },
            {
                "$id": "4",
                "Reichweite": {
                    "$ref": "1"
                },
                "Id": 2773,
                "GRP": 30,
                "RW_TV": 3500,
                "Cost_TV": 46800,
                "Rw_ZuWGS": 1500,
                "Cost_I_Rea": 10.4,
                "ReichweiteId": 21
            },
            {
                "$id": "5",
                "Reichweite": {
                    "$ref": "1"
                },
                "Id": 2774,
                "GRP": 40,
                "RW_TV": 4500,
                "Cost_TV": 62400,
                "Rw_ZuWGS": 1000,
                "Cost_I_Rea": 15.6,
                "ReichweiteId": 21
            }
        ],
        "Id": 21,
        "Name": "Short Curve",
        "Potenzial": 132132132,
        "Geschlecht": "men",
        "CpGRP": 1560,
        "ZielGRP": 1560,
        "Benutzer": "admin"
    }
]

Maybe you can tell me what the "$id" and "$ref" is.

Best and thank you very much

converting the German to english helps a lot too before posting

Scott Selby · Accepted Answer · 2014-10-27 17:27:41Z

0

If I understood correctly form your comments you say that you are already getting all the data just fine - you just need it converted into JOSN

simple just change the last line of the controller action form :

return reich;

to:

return this.Json(reich);

MVC and WebApi have built in JSON serializers

try this:

public IHttpActionResult GetReichweite(int id)
        {
            var obj = db.Points.Take(100);                
            return Ok(obj);
        }

that should simpify things abit

edited Oct 27, 2014 at 17:27

answered Oct 27, 2014 at 14:13

Scott Selby

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5 Comments

Andreas Klumpe Over a year ago

Do not work. Something went wrong in the method. (from item in reich select new Points() reich is red underlined "missing deklaration"

Scott Selby Over a year ago

yea - your whole query doesn't look like it could possibly work the way you have it written , I wasn't sure about that . You did say you were successfully getting data back - and asked how to convert that data into JSON - this answer here is how to do that

Andreas Klumpe Over a year ago

Sorry my fail. Can you help me to get the data which i need.

Scott Selby Over a year ago

updated answer - take out async until you get it working normally

Andreas Klumpe Over a year ago

Ok i´ve try it but get an Self referencing loop detected for property error back.

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