jared jared - 23 days ago 7
JSON Question

Deserialize JSON object with blank array

I'm having a little trouble deserializing a JSON object when there's an empty/null property (using JSON.NET), and hoping someone can point me in the right direction. Below is a snippet of code I'm trying, and been testing at dotnetfiddle

Here's a sample of the JSON:

{
"`LCA0009": [],
"`LCA0001": {
"23225007190002": "1",
"23249206670003": "1",
"01365100070018": "5"
},
"`LCA0003": {
"23331406670018": "1",
"24942506670004": "1"
},
"`LCA0005": {
"01365100070018": "19"
}
}


I'm trying to use this code:

using System;
using System.Collections.Generic;
using Newtonsoft.Json;

public class Program
{
public static void Main()
{

string json = "{\"`LCA0009\": [], \"`LCA0001\": {\"23225007190002\": \"1\",\"23249206670003\": \"1\",\"01365100070018\": \"5\"},\"`LCA0003\": {\"23331406670018\": \"1\",\"24942506670004\": \"1\"},\"`LCA0005\": {\"01365100070018\": \"19\"}}";
Console.WriteLine(json);
Console.WriteLine();

Console.WriteLine("This works");
var root = JsonConvert.DeserializeObject(json);
Console.WriteLine(root);

Console.WriteLine("This doesn't work");
var root2 = JsonConvert.DeserializeObject<Dictionary<string, Dictionary<string, int>>>(json);
Console.WriteLine(root2);

foreach (var locationKvp in root2)
{
foreach (var skuKvp in locationKvp.Value)
{
Console.WriteLine("location: " + locationKvp.Key + ", sku: " + skuKvp.Key + ", qty: " + skuKvp.Value);
}
}
}
}


The "doesn't work" above is that I get this error:


Run-time exception (line 19): Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'System.Collections.Generic.Dictionary`2[System.String,System.Int32]' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly.
To fix this error either change the JSON to a JSON object (e.g. {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array.
Path '`LCA0009', line 1, position 14.


How can I remove the properties that have a null/empty array?

Answer

Fundamentally, the JSON is inconsistent and the best answer is to make it consistent. Whoever is giving you that JSON needs to be told to fix it.

Until/unless you can do that, you can convert the "raw" version to Dictionary<string, Dictionary<string, int>> yourself, but it's more work:

https://dotnetfiddle.net/zdeOOX

string json = "{\"`LCA0009\": [], \"`LCA0001\": {\"23225007190002\": \"1\",\"23249206670003\": \"1\",\"01365100070018\": \"5\"},\"`LCA0003\": {\"23331406670018\": \"1\",\"24942506670004\": \"1\"},\"`LCA0005\": {\"01365100070018\": \"19\"}}";

// Convert it
var root = (JObject)JsonConvert.DeserializeObject(json);
var results = new Dictionary<string, Dictionary<string,int>>();
foreach (var entry in root)
{
    var dict = new Dictionary<string,int>();
    if (!(entry.Value is JArray))
    {
        foreach (var subentry in (JObject)entry.Value)
        {
            int v;
            if (int.TryParse(((JValue)subentry.Value).ToString(), out v))
            {
                dict.Add(subentry.Key, v);
            }
        }
    }
    results.Add(entry.Key, dict);
}

// Results:
foreach (var name in results.Keys)
{
    var entry = results[name];
    Console.WriteLine(name + ":");
    foreach (var entryKey in entry.Keys)
    {
        Console.WriteLine("- " + entryKey + ": " + entry[entryKey]);
    }
}

I expect that can be made much more elegant with Linq.

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