Parsing dynamic JSON with Newtonsoft.JSON is missing array in the deserialized object

Question

When I get to the third loop, it blows up because it can't find the "Row" on the table. Why?

var converter = new ExpandoObjectConverter();
dynamic deserializeObject = JsonConvert.DeserializeObject<ExpandoObject>(jsonString, converter);

foreach (var model in deserializeObject.Model)
{
    foreach (var table in model.Table)
    {
        foreach (var row in table.Row)
        {
            Console.WriteLine(row.BookId + ": " + row.BookName);
        }
    }
}

JSON:

{
  "Model": [
    {
      "Field1": "Field1Value",
      "Field2": "Field2Value",
      "Field3": "Field3Value",
      "Table": {
        "Row": [
          {
            "BookId": "1",
            "BookName": "Computer Architecture",
            "Category": "Computers",
            "Price": "125.60"
          },
          {
            "BookId": "2",
            "BookName": "Asp.Net 4 Blue Book",
            "Category": "Programming",
            "Price": "56.00"
          },
          {
            "BookId": "3",
            "BookName": "Popular Science",
            "Category": "Science",
            "Price": "210.40"
          },
          {
            "BookId": "4",
            "BookName": "Mission Impossible",
            "Category": "Adventure",
            "Price": "210.40"
          }
        ]
      }
    },
    {
      "ClientFirstName": "Jane",
      "ClientLastName": "Doe",
      "Table": [
        {
          "Row": [
            {
              "BookId": "1",
              "BookName": "Computer Architecture",
              "Category": "Computers",
              "Price": "125.60"
            },
            {
              "BookId": "3",
              "BookName": "Popular Science",
              "Category": "Science",
              "Price": "210.40"
            },
            {
              "BookId": "4",
              "BookName": "Mission Impossible",
              "Category": "Adventure",
              "Price": "210.40"
            }
          ]
        },
        {
          "Row": [
            {
              "BookId": "1",
              "BookName": "Computer Architecture",
              "Category": "Computers",
              "Price": "125.60"
            },
            {
              "BookId": "4",
              "BookName": "Mission Impossible",
              "Category": "Adventure",
              "Price": "210.40"
            }
          ]
        }
      ]
    }
  ]
}

check your json in jsonlint.com

tofutim
– tofutim

2016-04-07 02:39:32 +00:00
Commented Apr 7, 2016 at 2:39 — tofutim
– tofutim, Commented Apr 7, 2016 at 2:39

Timothy von Hollen · Accepted Answer · 2016-04-07 05:10:47Z

The problem isn't with the way you're deserializing the object. Your json is different between the two objects that contain a table.

The first object is a table that has an array of rows:

    "Table": {
    "Row": [
      {
        "BookId": "1",
        "BookName": "Computer Architecture",
        "Category": "Computers",
        "Price": "125.60"
      },
      {
        "BookId": "2",
        "BookName": "Asp.Net 4 Blue Book",
        "Category": "Programming",
        "Price": "56.00"
      },
      {
        "BookId": "3",
        "BookName": "Popular Science",
        "Category": "Science",
        "Price": "210.40"
      },
      {
        "BookId": "4",
        "BookName": "Mission Impossible",
        "Category": "Adventure",
        "Price": "210.40"
      }
    ]
  }
}

And your second client object has an array of an array. In addition you have a second array of rows in that client object outside of the table array.

       "Table": [
    {
      "Row": [
        {
          "BookId": "1",
          "BookName": "Computer Architecture",
          "Category": "Computers",
          "Price": "125.60"
        },
        {
          "BookId": "3",
          "BookName": "Popular Science",
          "Category": "Science",
          "Price": "210.40"
        },
        {
          "BookId": "4",
          "BookName": "Mission Impossible",
          "Category": "Adventure",
          "Price": "210.40"
        }
      ]
    },
    {
      "Row": [
        {
          "BookId": "1",
          "BookName": "Computer Architecture",
          "Category": "Computers",
          "Price": "125.60"
        },
        {
          "BookId": "4",
          "BookName": "Mission Impossible",
          "Category": "Adventure",
          "Price": "210.40"
        }
      ]
    }

I'd recommend either formatting your json differently or creating a different method to loop though the two types of tables you have in that json. One being an object and the other an array.

For example. I changed your dynamic to a Newtonsoft Jobject which is in Newtonsoft.Json.Linq; This will pick up on both tables, one being an object and the second being an array.

       var converter = new ExpandoObjectConverter();
        var deserializeObject = JsonConvert.DeserializeObject<JObject>(jsonString, converter);

        foreach(var v in deserializeObject["Model"])
        {
            if(v["Table"] != null && v["Table"].Type == JTokenType.Object)
            {
                foreach (var x in v["Table"]["Row"])
                {
                    Console.Write(x["BookId"] + " : " + x["BookName"] + Environment.NewLine);
                }
            }
            else if (v["Table"].Type == JTokenType.Array)
            {
                foreach(var subTable in v["Table"])
                {
                    foreach (var row in subTable["Row"])
                    {
                        Console.Write(row["BookId"] + " : " + row["BookName"] + Environment.NewLine);
                    }
                }

            }              
        }

har07 · Accepted Answer · 2016-04-08 02:18:25Z

Table property in your JSON was formatted as array in one instance and as object in another. The former deserializes to List<object> while the latter deserializes to KeyValuePair<string, object>.

You can check whether Table in the current instance is of type KeyValuePair<string, object> and then proceed accordingly :

foreach (var model in deserializeObject.Model)
{
    foreach (var table in model.Table)
    {
        if(table is KeyValuePair<string, object>)
        {
            foreach (var row in table.Value)
            {
                Console.WriteLine(row.BookId + ": " + row.BookName);
            }
        }
        else
        {
            foreach (var row in table.Row)
            {
                Console.WriteLine(row.BookId + ": " + row.BookName);
            }
        }
    }
}

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