CODEWITHSUNDEEP
c#linquwp
RichPro
RichPro

Reputation: 23

Error when using XDocument in code behind

I have a UWP project that requires data from an XML file. I am developing the project in Blend.

When I add the line:

XDocument xdoc = XDocument.Load("E:/VisualStudioRepo/ImportFromXML/ImportFromXML/Assets/XML/Book2.xml");

I get an error:

An exception of type 'System.InvalidOperationException' occurred in System.IO.FileSystem.dll but was not handled in user code

Additional information: Synchronous operations should not be performed on the UI thread. Consider wrapping this method in Task.Run.

I can replicate this error by just by starting a new project, adding a xaml button and the following code behind:

public void GetSentence()
{
    XDocument xdoc = XDocument.Load("E:/VisualStudioRepo/ImportFromXML/ImportFromXML/Assets/XML/Book2.xml");
}

private void button_Click(object sender, RoutedEventArgs e)
{
    GetSentence();
}

I have tested my full Linq code in a Visual Studio Console application and I can read the xml perfectly there and output lists of all or part of the xml file. So the xml file is OK and my basic methodology seems to work. It just won't work in the UWP environment.

Do I really have to "wrap this method in a Task.Run"? If so, please tell me how to do it. What surprises me is that I can't see anyone else with this precise problem on the web despite hours of searching, so I suspect I am doing something wrong.

I am a self-confessed amateur programmer who loves programming (and an 'old bloke' as well), so please help me with a clear explanation and please don't tell me to go back to school as that was a real long time ago!

Upvotes: 2

Views: 159

Answers (2)

RichPro
RichPro

Reputation: 23

Here is what I did based on advice from @Jeremy:

var newTask = Task.Run(() => GetSentence()) ;

Note that there is no bracket before GetSentence.

This is what I did based on advice from @Karolis and resulting research:

Moved my XML document to the documentsLibrary.

Added 'documentsLibrary' to Capabilities in my appxmanifest file (note this step has to be done in the code as it is not exposed in the UI).

<Capabilities>
  <uap:Capability Name="documentsLibrary" />   
</Capabilities>

Added '.xml' to Extensions in my appxmanifest file (can be done in the UI on the Declarations tab).

<Extensions>
   <uap:Extension Category="windows.fileTypeAssociation">
      <uap:FileTypeAssociation Name=".xml">
         <uap:SupportedFileTypes>
            <uap:FileType>.xml</uap:FileType>
         </uap:SupportedFileTypes>
      </uap:FileTypeAssociation>
   </uap:Extension>
</Extensions>

Upvotes: 0

Jeremy Glazebrook
Jeremy Glazebrook

Reputation: 96

While I'm not too sure why you are getting this error, I will definitely help you out on using Task.Run().

Task.Run allows you to run tasks on a background thread, so that you don't block the UI thread.

You can use it like so:

private void button_Click(object sender, RoutedEventArgs e)
{
    var newTask = Task.Run(() => (GetSentence());
}

What this does is calls the GetSentence() method on a different thread, while still giving you the same result.

You can also do this as well to get the same effect!

var newTask = Task.Run(() => {  XDocument xdoc = XDocument.Load("E:/VisualStudioRepo/ImportFromXML/ImportFromXML/Assets/XML/Book2.xml"); });

Lastly, the Developer Network has a great article here with similar examples: You can find more info here

Upvotes: 0

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