C＃.NET錯誤：無法強制轉換'System.Data.DataTable'類型的對象來鍵入'System.Data.DataSet'

Question

我有一個可編輯的GridView，它的數據存儲在XML文件中，當我試圖插入/更新/在GridView刪除數據/，我得到以下錯誤：

Unable to cast object of type 'System.Data.DataTable' to type 'System.Data.DataSet

GridView的成功顯示存儲在XML文件中的數據，但如果出現錯誤，當我試圖插入/更新/刪除行。

我可以得到一些方向，我在這裏失蹤了嗎？

XML文件：

<root> 
<pos> 
    <partNumbers> 
    <partid>0</partid> 
    <partnumber>796542</partnumber> 
    </partNumbers> 
    <partNumbers> 
    <partid>1</partid> 
    <partnumber>225614</partnumber> 
    </partNumbers> 
    <partNumbers> 
    <partid>2</partid> 
    <partnumber>123457</partnumber> 
    </partNumbers> 
</pos> 
</root> 

我的C＃代碼：

//Bind Data 
protected void BindGridView() 
{ 
     DataSet dsgvPartNumber = new DataSet(); 
     dsgvPartNumber.ReadXml(Server.MapPath("~/xml/storeUserInfo.xml")); 
     gvPartNumber.DataSource = dsgvPartNumber.Tables["partNumbers"]; 
     gvPartNumber.DataBind(); 
     gvPartNumber.ShowFooter = true; 
} 

// Delete Row 
protected void gvPartNumber_RowDeleting(object sender, GridViewDeleteEventArgs e) 
{ 
     BindGridView(); 
     DataSet dsgvPartNumberDelete = (DataSet)gvPartNumber.DataSource; 
     dsgvPartNumberDelete.Tables[0].Rows[gvPartNumber.Rows[e.RowIndex].DataItemIndex].Delete(); 
     dsgvPartNumberDelete.WriteXml(Server.MapPath("~/xml/storeUserInfo.xml")); 
     BindGridView(); 
} 

// EditGridView 
protected void gvPartNumber_RowEditing(object sender, GridViewEditEventArgs e) 
{ 
     gvPartNumber.ShowFooter = false; 
     gvPartNumber.EditIndex = e.NewEditIndex; 
     BindGridView(); 
} 

// Update GridView 
protected void gvPartNumber_RowUpdating(object sender, GridViewUpdateEventArgs e) 
{ 
     int index = gvPartNumber.Rows[e.RowIndex].DataItemIndex; 
     string partId = ((TextBox)gvPartNumber.Rows[e.RowIndex].FindControl("txtPartID")).Text; 
     string partNumber = ((TextBox)gvPartNumber.Rows[e.RowIndex].FindControl("txtPartNumber")).Text; 
     gvPartNumber.EditIndex = -1; 
     BindGridView(); 
     DataSet dsUpdateXMLFile = (DataSet)gvPartNumber.DataSource; 
     dsUpdateXMLFile.Tables[0].Rows[index]["partid"] = partId; 
     dsUpdateXMLFile.Tables[0].Rows[index]["partnumber"] = partNumber; 
     dsUpdateXMLFile.WriteXml(Server.MapPath("~/xml/storeUserInfo.xml")); 
     BindGridView(); 
} 

// Insert New Row 
protected void gvPartNumber_RowCommand(object sender, GridViewCommandEventArgs e) 
{ 
     if (e.CommandName == "insertXMLData") 
     { 
      string partid = ((TextBox)gvPartNumber.FooterRow.FindControl("txtPartIDInsert")).Text; 
      string partnumber = ((TextBox)gvPartNumber.FooterRow.FindControl("txtPartNumberInsert")).Text; 
      BindGridView(); 
      DataSet dsXMLInsert = (DataSet)gvPartNumber.DataSource; 
      DataRow drInsert = dsXMLInsert.Tables[0].NewRow(); 
      drInsert["partid"] = partid; 
      drInsert["partnumber"] = partnumber; 
      dsXMLInsert.Tables[0].Rows.Add(drInsert); 
      dsXMLInsert.WriteXml(Server.MapPath("~/xml/storeUserInfo.xml")); 
      BindGridView(); 
     } 
} 

我能請得到一些方向/解釋什麼，我缺少的代碼？

預先感謝您。

Answer 1

這是因爲你設置DataSource到DataTable：

gvPartNumber.DataSource = dsgvPartNumber.Tables["partNumbers"]; 

不是DataSet。所以，與其這樣：

DataSet dsgvPartNumberDelete = (DataSet)gvPartNumber.DataSource; 

做到這一點：

DataTable dsgvPartNumberDelete = (DataTable)gvPartNumber.DataSource; 

，然後在下面幾行你就不必存取像.Tables[0]。它已經是DataTable，因此無論如何都是直接訪問。

此修改當然必須複製到您試圖將DataSource作爲DataSet投射的所有方法。

Answer 2

您的數據源是一個DataTable，而不是DataSet。您不能將DataTable轉換爲DataSet。

DataTable dtUpdateXMLFile = (DataTable)gvPartNumber.DataSource; 
dtUpdateXMLFile.Rows[index]["partid"] = partId; 
dtUpdateXMLFile.Rows[index]["partnumber"] = partNumber; 
dtUpdateXMLFile.WriteXml(Server.MapPath("~/xml/storeUserInfo.xml"));