Deserialize Nested JSON to Lists

Question

I am trying to bind a drop-down with these lists in my View. Not able to convert the below JSON collections to LISTS.

My JSON string is in this format:

 ["AppTypes",
 [
    {
        "AppTypeID": "5136",
        "AppType": "ABC"
    },
    {
        "AppTypeID": "dca6",
        "AppType": "MNO"
    },
    {
        "AppTypeID": "d8de",
        "AppType": "PQR"
    }
],
"CompTypes",
[
    {
        "CompTypeID": "0425",
        "CompType": "STU"
    },        
    {
        "CompTypeID": "0426",
        "CompType": "EDC"
    },
    {
        "CompTypeID": "0444",
        "CompType": "PLM"
    }
]
]

I am trying to deserialize the code, but not getting through. My Class,

     public class DAL
     {
           public DAL() { }
           public CompList CompList { get; set; }
     }

     public class CompList
     {
         public CompList()
         {
              AppTypes = new List<AppTypes>();
              CompType = new List<CompTypes>();                   
         }
         public List<AppTypes> AppTypes;
         public List<ComTypes> CompType;
     }
     public class AppTypes
     {
         public Guid AppTypeID { get; set; }
         public string AppType { get; set; }
     }

     public class CompTypes
     {
         public Guid CompTypeID { get; set; }
         public string CompType { get; set; }
     }

     public class JSONSerializer
     {
          public static T ConvertFromJSON<T>(String json)
          {
              JavaScriptSerializer serializer = new JavaScriptSerializer();
              return serializer.Deserialize<T>(json);
          }
     }

Controller Code:

    dynamic obj = JSONSerializer.ConvertFromJSON<DAL>(JsonData);

Not able to get where I am going wrong. Any help would be really appreciated.

Answer 1

The main problem here is that your JSON represents a top-level array containing either strings or nested arrays containing objects, but you are trying to deserialize this into a top-level object - not an array. Your class design is quite reasonable, but a serializer such as JavaScriptSerializer isn't really designed to completely restructure a data model in this way during deserialization. You may need to deserialize into a more literal representation of the JSON, then restructure the data with, say, Linq.

A secondary problem is that you are declaring your ID properties to be Guids, but the corresponding JSON properties (such as "AppTypeID": "5136") do not have enough digits to be Guids. JavaScriptSerializer expects a Guid to have 32 digits, optionally separated by hyphens, e.g.: "d70d7583-b2e6-4f6e-8d99-2022d3ca2b10" or "d70d7583b2e64f6e8d992022d3ca2b10".

Thus, if I change your Guid properties to strings:

public class AppTypes
{
    public string AppTypeID { get; set; }
    public string AppType { get; set; }
}

public class CompTypes
{
    public string CompTypeID { get; set; }
    public string CompType { get; set; }
}

Then I can deserialize and convert to a CompList as follows:

        var js = new JavaScriptSerializer();
        var array = js.Deserialize<List<object>>(JsonData); // Deserialize outer array
        var compList = new CompList
        {
            AppTypes = array
                .OfType<IEnumerable<object>>()          // Enumerate through nested arrays
                .SelectMany(o => o)                     // Enumerate through elements in nested arrays
                .OfType<IDictionary<string, object>>()  // Pick out those which are JSON objects (deserialized as dictionaries)
                .Where(d => d.ContainsKey("AppType"))   // Filter those that are AppTypes 
                .Select(d => js.ConvertToType<AppTypes>(d)) // Deserialize to the AppTypes class
                .ToList(),
            CompType = array
                .OfType<IEnumerable<object>>()
                .SelectMany(o => o)
                .OfType<IDictionary<string, object>>()
                .Where(d => d.ContainsKey("CompType"))
                .Select(d => js.ConvertToType<CompTypes>(d))
                .ToList(),
        };

FYI, your original code could deserialize JSON that looks like this into a CompList:

{
  "AppTypes": [
    {
      "AppTypeID": "5136",
      "AppType": "ABC"
    },
    {
      "AppTypeID": "dca6",
      "AppType": "MNO"
    },
    {
      "AppTypeID": "d8de",
      "AppType": "PQR"
    }
  ],
  "CompType": [
    {
      "CompTypeID": "0425",
      "CompType": "STU"
    },
    {
      "CompTypeID": "0426",
      "CompType": "EDC"
    },
    {
      "CompTypeID": "0444",
      "CompType": "PLM"
    }
  ]
}

Note that the outermost JSON is an object with two array-valued properties rather than an array of two strings and two arrays.