javascript custom converter deserialize json array

Question

I have an object model that includes an array of longs and I'm deserializing a json string that contains an array using a custom javascript converter and the javascript serializer class.

I thought this would work but it doesn't:

List<long> TheList = new List<long>;

if (dictionary.ContainsKey("TheArray") && dictionary["TheArray"] != null)
{
    TheList = serializer.ConvertToType<List<long>>(dictionary["TheArray"]); //bug
    TheObject.TheObjectList = (from s in TheList 
                               select Convert.ToInt64(s)).ToList<long>();
}

The error is on the line TheList = serializer.ConvertToType... and the error message is:

Cannot convert object of type 'System.String' to type 'System.Collections.Generic.List`1[System.Int64]'

I also tried this:

var TheStringArray = serializer.ConvertToType<string>(dictionary["TheArray"]);

TheObject.TheObjectList = (from s in TheStringArray.Split(',') 
                           select Convert.ToInt64(s)).ToList<long>();

But then I get this error message:

Type 'System.String' is not supported for deserialization of an array.

What am I missing?

Thanks.

Are all the values in the array (string?) valid Int64 values? — Jocke
– Jocke, Commented Feb 6, 2013 at 12:17
yes, they're all javascript int values. As a precaution, I'm actually also parsing the values to Int64 on the following line. — frenchie
– frenchie, Commented Feb 6, 2013 at 12:20
The json is a dictionary that contains an array of number, all classic, nothing fancy. — frenchie
– frenchie, Commented Feb 6, 2013 at 12:38

tpeczek · Accepted Answer · 2013-02-06 12:46:40Z

1

Array is visible to JavaScriptConverter as ArrayList, you may approach the deserialization like this:

List<long> theArray = null;

if (dictionary.ContainsKey("TheArray") && dictionary["TheArray"] is ArrayList)
{
    theArray = new List<long>();
    ArrayList serializedTheArray = (ArrayList)dictionary["TheArray"];
    foreach (object serializedTheArrayItem in serializedTheArray)
    {
        if (serializedTheArrayItem is Int64)
            theArray.Add((long)serializedTheArrayItem);
    }
}

This will do all types checking in case there is somethign unexpected in the JSON. Of course it assumes that TheArray property in JSON in fact contains an Array, not inner JSON string which represents Array (the error message might suggest this kind of issue).

answered Feb 6, 2013 at 12:46

tpeczek

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1 Comment

frenchie Over a year ago

ok, I'm able to get your serializedTheArray to contain the array. Now I'm working on writing the second line with linq like I have it in the question instead of the foreach loop.

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