Question

I’m trying to deserialize the JSON string

[{ "key" : "1", "value" : "open"}, {"key" : "2", "value" : "closed"}, {"key" : "3", "value" : "pending"}]

into a C# array. I’m getting the error “No parameterless constructor defined for type of ‘System.Array’.” I’m pulling the JSON from a database, then I wanted to deserialize it so I could access the values and update another field in my database with whatever a user passed in. This is just an example that I’m trying though and I need it to be dynamic, not static, since the JSON string contained in the database can be variable.

I tried using a dictionary earlier, but had no luck with that. So I’m trying a different approach now by deserializing it to an array then I was going to populate the dictionary from the array.

This is the method I’m trying to implement with at the moment…although I’ve tried several others…

 IList<Array> ValueArray = new JavaScriptSerializer().Deserialize<IList<Array>>(this.Parameter.ValueList); 
 //this.Parameter.ValueList just contains my JSON string

I’m thinking that I can’t do this without creating my own class?

When I tried using a dictionary, I tried this

Dictionary<string, string> ValueList =
                JsonConvert.DeserializeObject<Dictionary<string, string>>(this.Parameter.ValueList);  

but received this error

“Cannot deserialize the current JSON array (e.g. [1,2,3]) into type
‘System.Collections.Generic.Dictionary`2[System.String,System.String]’
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 ”, line 1, position 1.”

So I started to try using an array instead.

Answer 1

var list = new JavaScriptSerializer().Deserialize<List<KeyValue>>(json);

public class KeyValue
{
    public string key;
    public string value;
}

or just use KeyValue temporarily

var dict = new JavaScriptSerializer().Deserialize<List<KeyValue>>(json)
                                     .ToDictionary(x => x.key, x => x.value);

If you are open to use Json.Net , you can directly convert it to Dictionary

var dict = JsonConvert.DeserializeObject<JArray>(json)
                     .ToDictionary(x => (string)x["key"], x => (string)x["value"]);