Keep Coding

I have a JSON object as below
[
{
"Id": 7,
"Name": "Colocation Folder",
"ParentId": 1,
"depth": 0
},
{
"Id": 8,
"Name": "CoLo Real Estate",
"ParentId": 7,
"depth": 1
},
{
"Id": 10,
"Name": "CoLo: Burst",
"ParentId": 7,
"depth": 1
},
{
"Id": 34,
"Name": "CoLo Dedicated Bandwidth",
"ParentId": 7,
"depth": 1
},
{
"Id": 10035,
"Name": "Infrastructure as a Service",
"ParentId": 7,
"depth": 1
},
{
"Id": 10037,
"Name": "Software as a Service",
"ParentId": 7,
"depth": 1
},
{
"Id": 10038,
"Name": "IaaS Component Upgrade",
"ParentId": 7,
"depth": 1
},
{
"Id": 668,
"Name": "CoLo Misc Folder",
"ParentId": 7,
"depth": 1
},
{
"Id": 758,
"Name": "CoLo: Conduit Fee",
"ParentId": 668,
"depth": 2
},
{
"Id": 765,
"Name": "CoLo: Private VLAN",
"ParentId": 668,
"depth": 2
}
]
The Id and ParentId fields show the relation between the items. I need to make it as a nested JSON using C#.
Since there will be many such models, I don't want to create individual classes for each model. Is there a generic approach in C# that will take a flat JSON array, take the ID and ParentId fields as input and then return me a nested JSON with all other fields in the array as well? For example, I am looking for an output of nested JSON as below:
[
{
"Id": 7,
"Name": "Colocation Folder",
"items": [
{
"Id": 8,
"Name": "CoLo Real Estate",
"ParentId": 7
},
{
"Id": 10,
"Name": "CoLo: Burst",
"ParentId": 7
},
{
"Id": 34,
"Name": "CoLo Dedicated Bandwidth",
"ParentId": 7
},
{
"Id": 10035,
"Name": "Infrastructure as a Service",
"ParentId": 7
},
{
"Id": 10037,
"Name": "Software as a Service",
"ParentId": 7
},
{
"Id": 10038,
"Name": "IaaS Component Upgrade",
"ParentId": 7
},
{
"Id": 668,
"Name": "CoLo Misc Folder",
"ParentId": 7,
"items": [
{
"Id": 758,
"Name": "CoLo: Conduit Fee",
"ParentId": 668
},
{
"Id": 765,
"Name": "CoLo: Private VLAN",
"ParentId": 668
}
]
}
]
}
]

If you use Json.Net, you can do this conversion in a generic way using the LINQ-to-JSON API (JObjects). The idea is to parse the JSON array and add all the individual items to a dictionary keyed by Id. Then, loop over the dictionary items, and for each one, try to look up the parent. If the parent is found, add the item to the parent's items array (creating it if needed). Otherwise, add the item to the root array. Along the way, remove the depth property from each item, since you don't seem to want that in the output. Lastly, just dump the root array to string to get the final result.
var dict = JArray.Parse(json)
.Children<JObject>()
.ToDictionary(jo => (string)jo["Id"], jo => new JObject(jo));
var root = new JArray();
foreach (JObject obj in dict.Values)
{
JObject parent;
string parentId = (string)obj["ParentId"];
if (parentId != null && dict.TryGetValue(parentId, out parent))
{
JArray items = (JArray)parent["items"];
if (items == null)
{
items = new JArray();
parent.Add("items", items);
}
items.Add(obj);
}
else
{
root.Add(obj);
}
JProperty depth = obj.Property("depth");
if (depth != null) depth.Remove();
}
Console.WriteLine(root.ToString());
Fiddle: https://dotnetfiddle.net/Buza6T

You can use a dynamic object with JSON.Net like so to detect your properties dynamically then you could build a new json object with the desired nesting:
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
dynamic d = JArray.Parse(stringy);
foreach(var ob in d)
{
if(ob.ParentID != ob.Id)
{
string debug = "oh snapple, it's a child object";
}
}