C# Serialize Dictionary to JSON

Question

I am trying to serialize a Dictionary to JSON, and get the following exception:

new JavaScriptSerializer().Serialize(mydict)`

Type 'System.Collections.Generic.Dictionary`2[[System.UInt64, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.Nullable`1[[System.UInt64, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]], mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]' is not supported for serialization/deserialization of a dictionary, keys must be strings or objects.

Is there an easy way to do this? Maybe converting the ulongs to strings via LINQ or something relatively terse?

This is such an awful error message, isn't a value object still an object? — JoshBerke, May 13 '11 at 14:32
possible duplicate of [How do I convert a dictionary to a JSON String in C#?](http://stackoverflow.com/questions/5597349/how-do-i-convert-a-dictionary-to-a-json-string-in-c) — Jim G., Mar 07 '14 at 16:39
I clearly posted the question first. Why isn't the other one marked as a duplicate? — Mark Richman, Mar 07 '14 at 20:18

score 18 · Accepted Answer · edited Jul 24 '16 at 09:44

18

var dict = mapping.ToDictionary(item => item.Key.ToString(), item => item.Value.ToString());`

that will convert any Dictionary<K,V> to Dictionary<string,string> and serialization then works.

edited Jul 24 '16 at 09:44

Mosh Feu

28,354
16
88
135

answered Sep 10 '10 at 15:16

Mark Richman

28,948
25
99
159

1

This works perfectly. Worthwhile to note that something like a Dictionary can also be serialized in this way while preserving the complex type: mapping.ToDictionary(item => item.Key.ToString(), item => item.Value); – John Nelson Apr 05 '11 at 15:10

score 3 · Answer 2 · edited Jul 24 '16 at 09:45

3

use NewtonSoft.Json instead of JavaScriptSerializer to overcome this problem:

Ex:

JsonConvert.SerializeObject(mydict);

edited Jul 24 '16 at 09:45

Mosh Feu

28,354
16
88
135

answered Sep 16 '15 at 12:52

Binod Mahto

340
2
13

score 1 · Answer 3 · answered Jun 01 '11 at 11:18

1

The blog http://dukelupus.wordpress.com/2011/05/04/asp-net-mvc-json-and-a-generic-dictionary/ describes an extension method Dictionary ToJsonDictionary(this Dictionary input)

answered Jun 01 '11 at 11:18

Michael Freidgeim

26,542
16
152
170

While this answer is several years old [it would be preferable](http://meta.stackexchange.com/q/8259) to include the essential parts of the answer here, and provide the link for reference. – Taryn Mar 09 '14 at 13:57

C# Serialize Dictionary to JSON

3 Answers3

Linked