vb.net 数据表序列化为 json

Posted 2023-02-22

【中文标题】vb.net 数据表序列化为 json

【英文标题】：vb.net datatable Serialize to json

【发布时间】：2014-03-06 01:32:14

【问题描述】：

我有这种桌子：

我需要得到这个 JSON（当然顺序可以是任意的，结构/树是最重要的）：

数据表可以改变，所以序列化应该是动态的。我正在使用 vb.net 并使用此代码：

 Public Function GetJson() As String
        Dim dt As New System.Data.DataTable
        dt = CreateDataTable() 'here I retrive data from oracle DB
        Dim serializer As New System.Web.Script.Serialization.javascriptSerializer()
        Dim packet As New List(Of Dictionary(Of String, Object))()
        Dim row As Dictionary(Of String, Object) = Nothing
        For Each dr As DataRow In dt.Rows
            row = New Dictionary(Of String, Object)()
            For Each dc As DataColumn In dt.Columns
                row.Add(dc.ColumnName.Trim(), dr(dc))
            Next
            packet.Add(row)
        Next
        Return serializer.Serialize(packet)
    End Function

但是这段代码返回了错误的 json：["NAME":"city","PARENT":"address","VALUE":"has child","NAME":"coordinates","PARENT":"address","VALUE":"has child","NAME":"street","PARENT":"address","VALUE":"has child".......

有人可以帮帮我吗？

【参考方案1】：

这是我的解决方案：

Public Function GetJson() As String

    Dim dt As New System.Data.DataTable
    dt = CreateDataTable() 'here I retrive data from oracle DB
    Dim serializer As New System.Web.Script.Serialization.JavaScriptSerializer()
    Dim packet As New List(Of Dictionary(Of String, Object))()
    Dim row As Dictionary(Of String, Object) = Nothing

    Try
        Dim result() As DataRow = dt.Select("Parent_ = 'main'")
        Dim i As Integer
        For i = 0 To result.GetUpperBound(0)
            row = New Dictionary(Of String, Object)()
            If UCase(result(i)(2)) <> "HAS CHILD" Then
                row.Add(result(i)(0), result(i)(2))
            Else
                row.Add(result(i)(0), add_(dt, result(i)(0)))
            End If
            packet.Add(row)
        Next i

        Return serializer.Serialize(packet)
    Catch ex As Exception
        MsgBox(ex.ToString)
        Me.Close()
    End Try

End Function

Public Function add_(ByVal dt As System.Data.DataTable, ByVal parent_ As String) As Dictionary(Of String, Object)
    Dim row As Dictionary(Of String, Object) = Nothing
    Try
        Dim result() As DataRow = dt.Select("Parent_ = '" & parent_ & "'")
        Dim i As Integer
        row = New Dictionary(Of String, Object)()
        For i = 0 To result.GetUpperBound(0)

            If UCase(result(i)(2)) <> "HAS CHILD" Then
                row.Add(result(i)(0), result(i)(2))
            Else
                row.Add(result(i)(0), add_(dt, result(i)(0)))
            End If
        Next i
    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try
    Return row
End Function

【参考方案2】：

“哦，不，你没有”版本：

Public Function GetJson(ByVal dt As DataTable) As String
    Return New JavaScriptSerializer().Serialize(From dr As DataRow In dt.Rows Select dt.Columns.Cast(Of DataColumn)().ToDictionary(Function(col) col.ColumnName, Function(col) dr(col)))
End Function

【讨论】：

你会反序列化为字典，还是可以处理数据表？不过，很棒的台词。