Deserializing json array into .net class

Question

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))

Rob · Accepted Answer · 2010-02-16 10:39:55Z

7

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)

edited Feb 16, 2010 at 10:39

answered Feb 16, 2010 at 10:34

Rob

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2 Comments

Rob Over a year ago

@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 :)

GordonBy Over a year ago

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.

GordonBy · Accepted Answer · 2010-02-16 10:40:51Z

2

Doing it all on one line worked a treat;

Dim lstTextAreas As List(Of jsTextArea) = js.Deserialize(textAreaJson, GetType(List(Of jsTextArea)))

answered Feb 16, 2010 at 10:40

GordonBy

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2 Comments

Rob Over a year ago

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! :)

GordonBy Over a year ago

Yah, two routes... same result, albeit yours less wordy that mine. Cheers for your help :)

Sky Sanders · Accepted Answer · 2010-02-16 10:46:53Z

0

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)

answered Feb 16, 2010 at 10:46

Sky Sanders

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Comments

mikro · Accepted Answer · 2016-10-30 03:37:33Z

0

Here's a function to Deserialize JSON of any type:

    Public Function DeserializeJson(Of T)(json As String) As T
        Return New JavaScriptSerializer().Deserialize(Of T)(json)
    End Function

answered Oct 30, 2016 at 3:37

mikro

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