Get the JSON Format using VB.net

Question

Suggest me to get the JSON format as describe below using VB.net

var fieldtypes = {

    name: { label: 'Name', type: 'text', icon: 'fa-user' },
    firstname: { label: 'First name', type: 'text', icon: 'fa-user' },

}

I want to get this format in web-method that call in form of AJAX call. I write the VB.net method for this but it doesn't generate JSON that describe in above.

VB.Net web-method

Public Class FormBuilder
    Public Property label() As String
    Public Property type() As String
    Public Property icon() As String
End Class

Web-method:

Public Shared Function LogsheetDetail(LogMasterID As Integer) As String
    Dim sCtrlTag As String = ""
    Dim sDataType As String = ""
    Dim finalVal As String = ""
    Dim oDs As DataSet
    Dim frmBuilder As New List(Of FormBuilder)()
    Try
        oDs = GenUser.TempLogsheetDetails(Conn, LogMasterID)
        If oDs.Tables(0).Rows.Count > 0 Then
            For i = 0 To oDs.Tables(0).Rows.Count - 1
                sDataType = oDs.Tables(0).Rows(i)("data_type").ToString()
                Select Case sDataType
                    Case "Text"
                        frmBuilder.Add(New FormBuilder() With { _
               .label = oDs.Tables(0).Rows(i)("parameter_name").ToString(), _
               .type = "text", _
               .icon = "fa-user" _
                })


                End Select
            Next

        End If


        oDs.Dispose()
    Catch ex As Exception
        Throw New Exception(ex.ToString)
    Finally
        If Not oDs Is Nothing Then oDs.Dispose()
    End Try
    Dim objJSSerializer As New System.Web.Script.Serialization.JavaScriptSerializer()

    Dim jsonString As String = objJSSerializer.Serialize(frmBuilder)

    Return jsonString

Answer 1

I believe the problem is that your code creates an array of objects instead of a single object. I assume you code is generating an output like this:

[
    { "label": "Name", "type": "text", "icon": "fa-user" },
    { "label": "First name", "type": "text", "icon": "fa-user" }
]

The ideal solution would be creating a dictionary instead of a list. However, the JsonSerializer class does not work very well with dictionaries and would need a workaround.

It would be simpler if you could use Newtonsoft Json instead of JavascriptSerializer. The following code generates the output you want, using the Newtonsoft Json NuGet package:

Dim dic = New Dictionary(Of String, FormBuilder)

dic.Add("name", New FormBuilder() With {
   .label = "name",
   .type = "text",
   .icon = "fa-user"
})

dic.Add("firstname", New FormBuilder() With {
   .label = "firstname",
   .type = "text",
   .icon = "fa-user"
})

Return Newtonsoft.Json.JsonConvert.SerializeObject(dic)