Unable to construct Object from JSON string

Question

I am passing a simple JSON string from my C# client to my webservice . Following is the string I send

"{ \"name\":\"S1\" }"

At the service end I use the following code

class DataDC
{

    public String attr { get; set; }
    public String attrVal { get; set; }

}

JavaScriptSerializer json_serializer = new JavaScriptSerializer();
DataDC dc = (DataDC)json_serializer.DeserializeObject(str);

I get the following error

"Unable to cast object of type 'System.Collections.Generic.Dictionary`2[System.String,System.Object]' to type 'DataDC'."

how is your json deserializer supposed to know about the DataDC object nad how to map it? — njzk2
– njzk2, Commented Aug 9, 2013 at 10:01

Adam Moszczyński · Accepted Answer · 2013-08-09 10:05:56Z

28

Shouldn't it be like this to deserialize to your class:

JavaScriptSerializer json_serializer = new JavaScriptSerializer();
DataDC dc = json_serializer.Deserialize<DataDC>(str);

Another thing is that you don have Name parameter in your model class therefore nothing will be passed to it. Your JSON should be like this: "{ \"attr\":\"some value\",\"attrVal\":\"some value\" }"

Or change your model class:

class DataDC {
    public String name{ get; set; }    
}

answered Aug 9, 2013 at 10:05

Adam Moszczyński

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1 Comment

elolos Over a year ago

@sameer could you please mention which of the two suggestions helped you (or both)?

Tim B James · Accepted Answer · 2013-08-09 10:09:49Z

Your Json string/object does not match any of the properties of DataDC

In order for this to work, you would at least need to have a property called name within the class. e.g.

public class DataDC
{

    public string name { get; set; }
    public string attr { get; set; }
    public string attrVal { get; set; }

}

This way you might get one property matched up.

Going with your existing Class, you would need the following Json string;

"{ \"attr\":\"S1\", \"attrVal\":\"V1\" }"

Note: You can also use the following code to deserialize;

DataDC dc = json_serializer.Deserialize<DataDC>(str);

Kenneth · Accepted Answer · 2013-08-09 10:02:14Z

0

The reason you can't deserialize it is because it doesn't look at all like your class. You should create a class like this:

public class DataDC
{
    public string name{get; set;}
}

answered Aug 9, 2013 at 10:02

Kenneth

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