XamlParseException occured. Root element is missing.

Question

Actually what I want to try is to store a Xaml for StackPanel as a file and then access the same file to again load StackPanel and all its content.

Hi there I have one stack panel - topPanel inside which there is another stack panel - MainPanel. There is one button in MainPanel which gets the Xaml code for MainPanel writes it to the file in D:\ and loads it in UIElement and attepts to add that element to topPanel so that the same Ui will be added to the topPanel. But while loading file in XamlReader I am getting above exception occured.

XAML

        

<Window x:Class="WpfApplication2.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="693.5" Width="558.5">
    <StackPanel x:Name="topPanel">
<StackPanel x:Name="MainPanel" Margin="8,0,0,0" Height="312">
<Label Content="Write text here to test binding"/>
<TextBox x:Name="TestInput" Height="64" />
<TextBlock x:Name="TestStatic" Height="55" />
<Button Content="Press to see XAML code" Click="ShowXAML"/>
<TextBox x:Name="XamlCode" Height="100" />

</StackPanel>
</StackPanel>
</Window>

        

<Window x:Class="WpfApplication2.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="693.5" Width="558.5">
    <StackPanel x:Name="topPanel">
<StackPanel x:Name="MainPanel" Margin="8,0,0,0" Height="312">
<Label Content="Write text here to test binding"/>
<TextBox x:Name="TestInput" Height="64" />
<TextBlock x:Name="TestStatic" Height="55" />
<Button Content="Press to see XAML code" Click="ShowXAML"/>
<TextBox x:Name="XamlCode" Height="100" />

</StackPanel>
</StackPanel>
</Window>

XAML.CS

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Markup;
using System.Text;
using System.IO;
using System.Xml;
using BindingsHelpers;


namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            EditorHelper.Register<BindingExpression, BindingConvertor>();
            Binding myBinding = new Binding("Text");
            myBinding.Source = TestInput;
            TestStatic.SetBinding(TextBlock.TextProperty, myBinding);


        }
        void ShowXAML(object sender, RoutedEventArgs e)
        {
            TextWriter writer = File.CreateText("d:\\xamlfile.xaml");
            //StringBuilder outstr=new StringBuilder();
            XamlCode.Clear();
            //this code need for right XML fomating 
            XmlWriterSettings settings = new XmlWriterSettings();
            settings.Indent = true;
            settings.OmitXmlDeclaration = true;
            XamlDesignerSerializationManager dsm = new XamlDesignerSerializationManager(XmlWriter.Create(writer, settings));
            //this string need for turning on expression saving mode 
            dsm.XamlWriterMode = XamlWriterMode.Expression;
          
            XamlWriter.Save(MainPanel, dsm);
            //XamlCode.Text = outstr.ToString();

            writer.Close();
            TextReader reader = File.OpenText(@"d:\xamlfile.xaml");
            string outstr = reader.ReadToEnd();
            XamlCode.Text = outstr;

            XmlReaderSettings xrs = new XmlReaderSettings();
            xrs.ValidationType = ValidationType.None;
            XmlReader xmlReader = XmlReader.Create(reader, xrs);

            UIElement obj = (UIElement)XamlReader.Load(xmlReader);  //here is the exception: Root element is missing.
            topPanel.Children.Add(obj);

        }
    }
}

Answer 1

Are you looking to persist the user interface or the data that is contained within?  If you are trying to save the data, you may want to consider serialization.

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Answer 2

I want to persist UI. The error was due to the fact that when I store the StackPanel MainPanel, it is stored as fragement not complete doc, with the root element. So I just set ConformanceLevel.Fragment. That worked. But now loading from fragment is returning Null. That is obj is null suring debugging.

Answer 3

This would appear to work:

  private void ShowXAML(object sender, RoutedEventArgs e)
  {
   TextWriter writer = File.CreateText("xamlfile.xaml");
   //StringBuilder outstr=new StringBuilder();
   //XamlCode.Clear();
   topPanel.Children.Clear();

   //this code need for right XML fomating 
   //XmlWriterSettings settings = new XmlWriterSettings();
   //settings.Indent = true;
   //settings.OmitXmlDeclaration = true;
   //XamlDesignerSerializationManager dsm = new XamlDesignerSerializationManager(XmlWriter.Create(writer, settings));
   //this string need for turning on expression saving mode 
   //dsm.XamlWriterMode = XamlWriterMode.Expression;

   //XamlWriter.Save(MainPanel, dsm);
   writer.Write(XamlWriter.Save(MainPanel));

   writer.Close();
   TextReader reader = File.OpenText("xamlfile.xaml");
   //string outstr = reader.ReadToEnd();
   //XamlCode.Text = outstr;

   //XmlReaderSettings xrs = new XmlReaderSettings();
   //xrs.ValidationType = ValidationType.None;
   //XmlReader xmlReader = XmlReader.Create(reader, xrs);
   XmlReader xmlReader = XmlReader.Create(reader);

   UIElement obj = (UIElement)XamlReader.Load(xmlReader);  //here is the exception: Root element is missing.
   topPanel.Children.Add(obj); 
  }

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It would be greatly appreciated if you would mark any helpful entries as helpful and if the entry answers your question, please mark it with the Answer link.

Answer 4

Or, ot preserve your XamlDesignerSerilizationManager settings:

  private void ShowXAML(object sender, RoutedEventArgs e)
  {
   TextWriter writer = File.CreateText("xamlfile.xaml");
   //StringBuilder outstr=new StringBuilder();
   //XamlCode.Clear();
   topPanel.Children.Clear();

   //this code need for right XML fomating 
   //XmlWriterSettings settings = new XmlWriterSettings();
   //settings.Indent = true;
   //settings.OmitXmlDeclaration = true;
   //XamlDesignerSerializationManager dsm = new XamlDesignerSerializationManager(XmlWriter.Create(writer, settings));
   XamlDesignerSerializationManager dsm = new XamlDesignerSerializationManager(XmlWriter.Create(writer));
   //this string need for turning on expression saving mode 
   dsm.XamlWriterMode = XamlWriterMode.Expression;

   XamlWriter.Save(MainPanel, dsm);
   //writer.Write(XamlWriter.Save(MainPanel,));

   writer.Close();
   TextReader reader = File.OpenText("xamlfile.xaml");
   //string outstr = reader.ReadToEnd();
   //XamlCode.Text = outstr;

   //XmlReaderSettings xrs = new XmlReaderSettings();
   //xrs.ValidationType = ValidationType.None;
   //XmlReader xmlReader = XmlReader.Create(reader, xrs);
   XmlReader xmlReader = XmlReader.Create(reader);

   UIElement obj = (UIElement)XamlReader.Load(xmlReader);  //here is the exception: Root element is missing.
   topPanel.Children.Add(obj); 
  }

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It would be greatly appreciated if you would mark any helpful entries as helpful and if the entry answers your question, please mark it with the Answer link.