views:

346

answers:

3

I'm having problems deserializing some json data, getting InvalidCastExceptions and the like.

Can anyone point me in the right direction?

Here's the json i'm wanting to deserialize;

[{"OrderId":0,"Name":"Summary","MaxLen":"200"},{"OrderId":1,"Name":"Details","MaxLen":"0"}]

Here's my code;

  Public Class jsTextArea
    Public OrderId As Integer
    Public Name As String
    Public MaxLen As String
  End Class

Dim js As New System.Web.Script.Serialization.JavaScriptSerializer
Dim rawdata = js.DeserializeObject(textAreaJson)
Dim lstTextAreas As List(Of jsTextArea) = CType(rawdata, List(Of jsTextArea))
+2  A: 

OrderId is an Int in your json (note the lack fo quotes round the values), but you're declaring it as String in "jsTextArea". Also, unless the type that rawdata is returned as has a cast to List(Of jsTextArea), which it probably doesn't the code you've shown won't work.

Update To get the data out into a List(Of jsTextArea) try the following:

    Dim js As New System.Web.Script.Serialization.JavaScriptSerializer
    Dim lstTextAreas = js.Deserialize(Of List(Of jsTextArea))(textAreaJson)
Rob
@GordonB, see update I've just added. The code works for me :) It also seems to handle the conversion of int to string between the json and your class :)
Rob
Ah, ok.... Just found that using the straight deserialize method worked... Wa trying to split it into multiple lines to see where the error was occurring, but that didn't help :) I'll give you the answer, as you probably beat me to it by a few seconds..... Cheers.
GordonB
+2  A: 

Doing it all on one line worked a treat;

Dim lstTextAreas As List(Of jsTextArea) = js.Deserialize(textAreaJson, GetType(List(Of jsTextArea)))
GordonB
Working mainly in C# (thus using var for implicit typing of variables), my version of the line seems "cleaner", but they'll compile down to the same IL and do exactly the same thing no doubt! :)
Rob
Yah, two routes... same result, albeit yours less wordy that mine. Cheers for your help :)
GordonB
A: 
Dim textAreaJson As String = "[{""OrderId"":0,""Name"":""Summary"",""MaxLen"":""200""},{""OrderId"":1,""Name"":""Details"",""MaxLen"":""0""}]"
Dim js As New System.Web.Script.Serialization.JavaScriptSerializer
Dim lstTextAreas As jsTextArea() = js.Deserialize(Of jsTextArea())(textAreaJson)
Sky Sanders