添加在XML

Question

新元素我有這個xml文件

<?xml version="1.0" encoding="utf-8"?> 
<Root> 
    <Day id="Monday"> 
    <subject name="Software Testing" session="2010" group="Alpha" teacher="Tasawar Khan" classroom="Class Room 1" time="8:30"> 

    </subject> 
    </Day> 
    <Day id="Tuesday"> 
    <subject name="Digital Image Processing" session="2011" group="Alpha" teacher="Ali Javed" classroom="Class Room 2" time="11:30"> 

    </subject> 

    </Day> 
    <Day id="Wednesday"> 
    <subject name="Digital Image Processing" session="2011" group="Alpha" teacher="Ali Javed" classroom="Class Room 2" time="11:30"> 

    </subject> 
    </Day> 
    <Day id="Thursday"> 
    <subject name="Digital Image Processing" session="2011" group="Alpha" teacher="Ali Javed" classroom="Class Room 2" time="11:30"> 

    </subject> 
    </Day> 
    <Day id="Friday"> 
    <subject name="Digital Image Processing" session="2011" group="Alpha" teacher="Ali Javed" classroom="Class Room 2" time="11:30"> 

    </subject> 
    </Day> 

</Root> 

我想在裏面元素根據ID添加主題元素。 我已經爲它編寫了這段代碼。

using (IsolatedStorageFileStream isoStream = new IsolatedStorageFileStream(TeachersXMLPath, FileMode.Open,IsolatedStorageFile.GetUserStoreForApplication())) 
{ 
    string session = tb_session.Text.ToString(); 
    string subject = tb_subject.Text.ToString(); 
    DateTime? _datetime = val_timer.Value; 
    String time = _datetime.Value.Hour + ":" + _datetime.Value.Minute; 
    string crdthr = ((ListPickerItem)lst_credithr.SelectedItem).Content.ToString(); 
    string teacher = tb_teacher.Text.ToString(); 
    string classroom = tb_class.Text.ToString(); 
    XDocument loadedData = XDocument.Load(TeachersXMLPath); 
    var newElement = new XElement("subject", new XAttribute("name", subject), 
              new XAttribute("session", session), 
              new XAttribute("group", "alpha"), 
              new XAttribute("teacher", teacher), 
              new XAttribute("classroom", classroom), 
              new XAttribute("time", time)); 

    isoStream.Position = 0; 
    loadedData.Root.Add(newElement); 
    loadedData.Save(isoStream); 
} 

現在我面臨着兩個問題。

• 此代碼沒有提供任何錯誤，但是當我打開xml文件時根本沒有添加任何數據。
• 其次這個代碼即使工作（這不是）。它會裏面的數據。我怎麼能添加它與特定的ID。

Answer 1

嘗試改變FileMode到Create，而不是Open因爲你的代碼加載所有現有文件XDocument和寫入整個XDocument回獨立存儲在最後。

要在適當的<Day>標記下添加新的<Subject>，您需要先選擇<Day>標記。有幾種可能的方法可以做到這一點，例如：

var day = loadedData.Root.Element("Day") 
        .FirstOrDefault(o => (string)o.Attribute("id") == "Thursday"); 
day.Add(newElement); 
loadedData.Save(isoStream);