How to properly serialize my object that contains a list> into Json?

Question

I'm trying to serialize a collection of object named TableDTO. This object contains a Name, Date and a List>. I'm trying to serialize it using Newtonsoft.Json library in C#

Every things works good when i construct the object. I add the KeyValuePair like this :
mylist.Add(new KeyValuePair<string, string>($"Col{compteur}", value.Value));
Then i add the list to my TableDTO
TableDTO.List = mylist
Then i serialize my object like this
JsonConvert.SerializeObject(TableDto);
And here is what i got

{ "FileName" : "MEP_3_10$3aList.xlsx", "Conditions" :{"Predicate" : "<select a condition>"}, "DataRows" : [{"Key" : "Col1","Value" : "value"}, {"Key" : "Col2","Value" : "value"}] }

The problem I encountered is when i serialized it Instead of having

{
    {"Col1":"value"},
    {"Col2":"value"}
}

The list is serialized like this

{
    {"Key" : "Col1","Value" : "value"},
    {"Key" : "Col2","Value" : "value"}
}

I tried to use a converter as described on another post in stackoverflow but since the list is a property of my object it's not as easy.

Thanks a lot for your help

Can you please share more of your code? I recently did exactly the same as you are trying to do here, so please give me more information so I can help you. — Tony_KiloPapaMikeGolf, Dec 02 '16 at 08:27
Your desired JSON is invalid. Upload to http://jsonlint.com/ and you will get an error `Error: Parse error on line 1: { { "Col1": "value"`. In the [json standard](http://www.json.org/) a container surrounded by braces `{ ... }` is an unordered set of name / value pairs, but your outer container has no property names. — dbc, Dec 02 '16 at 08:33

score 1 · Answer 1 · answered Dec 02 '16 at 08:33

The problem you encounter is: NewtonSoft JSON can't handle dictionary key values and struct.

Please inspect my code:

public class CustomJSONSerializationHelper
{
    public string CustomSerialize(Dictionary<AuthorizationKey, ConditionalActionFlags> actionFlagMappings)
    {
        // ToArray() and use custom convertors, because NewtonSoft JSON can't handle dictionary key values and struct.
        var jsonString = JsonConvert.SerializeObject(actionFlagMappings.ToArray(), new Newtonsoft.Json.Converters.StringEnumConverter(), new AuthorizationKeyJsonConverter());
        return jsonString;
    }

    public Dictionary<AuthorizationKey, ConditionalActionFlags> CustomDeserialize(string jsonActionFlagMappings)
    {
        var resultArray = CustomDeserializeOverLoad(jsonActionFlagMappings);
        return (resultArray != null) ? resultArray.ToList().ToDictionary(pair => pair.Key, pair => pair.Value) : null;
    }

    public KeyValuePair<AuthorizationKey, ConditionalActionFlags>[] CustomDeserializeOverLoad(string jsonActionFlagMappings)
    {
        var result = JsonConvert.DeserializeObject<KeyValuePair<AuthorizationKey, ConditionalActionFlags>[]>(jsonActionFlagMappings,
             new Newtonsoft.Json.Converters.StringEnumConverter(), new AuthorizationKeyJsonConverter());
        return result;
    }
}

I call it like this:

    private string ObjectToJSON(Dictionary<AuthorizationKey, ConditionalActionFlags> actionFlagsMapping)
    {
        CustomJSONSerializationHelper customSerializationHelper = new CustomJSONSerializationHelper();
        return customSerializationHelper.CustomSerialize(actionFlagsMapping);
    }

You only have the dictionary problem. I even had to serialize a struct. Thats is why my code has an additional class AuthorizationKeyJsonConverter. You don't need this, only use the fix for the dictionary. — Tony_KiloPapaMikeGolf, Dec 02 '16 at 08:43
Were you able to use my code in your context? Please let me know. If not, please share your code and later today I will look at it. — Tony_KiloPapaMikeGolf, Dec 02 '16 at 08:59
Then please share your code if you can. (the .sln) So later today we can write it for you. It really is not so hard once you understand what to do. — Tony_KiloPapaMikeGolf, Dec 02 '16 at 09:29

How to properly serialize my object that contains a list> into Json?

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