Parsing a JSON array

Question

I'm trying to parse this array using JSON.NET

[[{"event_timestamp":1304587800,"event_time_8601":"2011-05-05T19:00:00+09:30","event_date":"Thursday, May 5th, 2011","event_time":"7:00 pm","venue_phone":"","event_notes":"","event_id":"2690119","links":[{"link_url":"http:\/\/tickets.sonicliving.com\/event\/2690119\/sl-tickets","link_title":"7:00 pm","link_type":"ticket"}],"event_title":"Justin Bieber","rsvp":"3","venue_id":"83659","venue_name":"Entertainment Centre Adelaide","venue_address":"","lat":"0","lon":"0","poster_url_large":"http:\/\/posters.sonicliving.com\/event\/2690119\/poster.png","poster_url_small":"http:\/\/posters.sonicliving.com\/event\/2690119\/smallposter.png","venue_city":"Adelaide","venue_state":"05","venue_country":"AU","eid":"181570318520944","eids":[0],"facebook_event_url":"http:\/\/www.facebook.com\/event.php?eid=181570318520944"}],[{"event_timestamp":1304766000,"event_time_8601":"2011-05-07T19:00:00+08:00","event_date":"Saturday, May 7th, 2011","event_time":"7:00 pm","venue_phone":"","event_notes":"","event_id":"2690126","links":[{"link_url":"http:\/\/tickets.sonicliving.com\/event\/2690126\/sl-tickets","link_title":"7:00 pm","link_type":"ticket"}],"event_title":"Justin Bieber","rsvp":"0","venue_id":"76921","venue_name":"Burswood Theatre","venue_address":"Great Eastern Highway","lat":"0","lon":"0","poster_url_large":"http:\/\/posters.sonicliving.com\/event\/2690126\/poster.png","poster_url_small":"http:\/\/posters.sonicliving.com\/event\/2690126\/smallposter.png","venue_city":"Perth","venue_state":"08","venue_country":"AU","eid":"173126412708252","eids":[0],"facebook_event_url":"http:\/\/www.facebook.com\/event.php?eid=173126412708252"}]]

I've tried the following code, but all I get is an exception:

Dim jResults As JArray = JArray.Parse(strJResults)

MessageBox.Show("You have " & jResults.Count & " results")

For Each jTok As JToken In jResults
    txtResult.Text = txtResult.Text & vbCrLf & jTok.Item("event_date").ToString()
Next

System.ArgumentException was unhandled
  Message="Accessed JArray values with invalid key value: "event_date". Array position index expected."
  Source="Newtonsoft.Json.Net35"
  StackTrace:
       at Newtonsoft.Json.Linq.JArray.get_Item(Object key) in d:\Development\Releases\Json\Working\Src\Newtonsoft.Json\Linq\JArray.cs:line 187
       at JSONNetTest.frmMain.frmMain_Load(Object sender, EventArgs e) in C:\Users\John Meyer\Documents\Visual Studio 2008\Projects\JSONNetTest\JSONNetTest\frmMain.vb:line 25
       at System.EventHandler.Invoke(Object sender, EventArgs e)
       at System.Windows.Forms.Form.OnLoad(EventArgs e)
       at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
       at System.Windows.Forms.Control.CreateControl()
       at System.Windows.Forms.Control.WmShowWindow(Message& m)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
  InnerException:

Any ideas?

Answer 1

The message "Array position index expected" is the clue to solving this. (It says: "Hey, I'm an array! Stop trying to ask me for a named property!")

Look at the format again:

[ [{...}], [{...}] ]

Each object with "event_date" is nested in its own array (of one element) which is in turn an element of the outer array. This secondary array also needs to be descended into before the "event_date" property can be accessed.

Consider the access should then be:

jTok.Item(0).Item("event_date")

Happy coding.

Answer 2

Sub Button5Click(sender As Object, e As EventArgs)
Dim APP As New Excel.Application
    Dim worksheet As Excel.Worksheet
    Dim worksheet2 As Excel.Worksheet
    Dim LastRow As Integer
            Dim workbook As Excel.Workbook

            Dim sourceString As String
            Dim url As String

            Dim i As Integer

            Dim wc As New System.Net.WebClient

            workbook = App.Workbooks.Open(room.Text)
            worksheet = workbook.Worksheets("sheet1")
            worksheet2 = workbook.Worksheets("sheet2")
            LastRow = worksheet.UsedRange.Rows.Count           

            For rrow As Integer =2 To LastRow
                url = CStr(worksheet.Cells(rrow, 1).Value)
                ' MsgBox(url)
            Try         

                wc.Headers("User-Agent")="Mozilla/5.0 (iPad; CPU OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A334 Safari/7534.48.3"  ' In my case user agent was table.
                sourceString = wc.DownloadString(url) 
                sourceString=sourceString.Trim()
                'MsgBox(sourceString)
                row.Text="URL# " & rrow-1 & " is getting processed"
                urlno.Text=url

                Dim allData As JArray = JArray.Parse(sourceString)
                i=0
                Try
                    For i=0 To allData.Count-1

                    Dim token As JToken=allData.First


                    Do Until token Is Nothing   

                        msgbox(token.Item("text").ToString())



                    msgbox(allData.Count & i+1) 
                    token=token.Next
                    Loop
                    Next


                Catch ex As Exception
                    worksheet.Cells(rrow, 2).Value=ex.ToString()
                    MsgBox(ex.ToString())

                End Try 

            Catch Outerex As Exception
                worksheet.Cells(rrow,2 ).Value="Unexpected Error"   
                MsgBox(Outerex.ToString())
            End Try

            Next
            MsgBox ("Done")     
            workbook.Save()
            workbook.Close()       
            App.Quit()      
    End Sub