Target Invocation Exception in async method

Question

I am trying to retrieve items from an rss feed but at times I get a TargetInvocationException 'unable to connect to remote server'. I am trying to use a try catch block to catch this error but I am not managing as I need the variable feed to be used throughout the other code and like this it is not visible. Any suggestions?

public static async Task<List<FeedItem>> getFeedsAsync(string url)
    {
       //The web object that will retrieve our feeds..
       SyndicationClient client = new SyndicationClient();

       //The URL of our feeds..
       Uri feedUri = new Uri(url);

       //Retrieve async the feeds..
       try
       {
           var feed = await client.RetrieveFeedAsync(feedUri);
       }
       catch (TargetInvocationException e)
       {

       }

       //The list of our feeds..
       List<FeedItem> feedData = new List<FeedItem>();

       //Fill up the list with each feed content..
       foreach (SyndicationItem item in feed.Items)
       {
             FeedItem feedItem = new FeedItem();
             feedItem.Content = item.Summary.Text;
             feedItem.Link = item.Links[0].Uri;
             feedItem.PubDate = item.PublishedDate.DateTime;
             feedItem.Title = item.Title.Text;

             try
             {
                 feedItem.Author = item.Authors[0].Name;
             }
             catch(ArgumentException)
             { }

             feedData.Add(feedItem);
         }

         return feedData;
    }

 }
}

Stephen Cleary · Accepted Answer · 2014-02-02 12:27:59Z

1

This kind of error cannot be prevented. It is an exogenous exception.

There is only one way to deal with those kinds of errors: your application must be designed to expect them and react in a reasonable way (e.g., bring up an error dialog or notification).

In particular, don't try to ignore them with an empty catch block.

answered Feb 2, 2014 at 12:27

Stephen Cleary

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2 Comments

Tamara Caligari Over a year ago

How do I show a pop up dialogue from the catch block?

Stephen Cleary Over a year ago

You use whatever APIs are available on your platform.

i3arnon · Accepted Answer · 2014-02-02 11:50:02Z

0

IAsyncOperationWithProgress<SyndicationFeed, RetrievalProgress> feed;

//Retrieve async the feeds..
try
{
   feed = await client.RetrieveFeedAsync(feedUri);
}
catch (TargetInvocationException e)
{

}

answered Feb 2, 2014 at 11:50

i3arnon

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2 Comments

Tamara Caligari Over a year ago

If I use this I get an error that I cannot convert from Windows.Web.Syndication.SyndicationFeed to Windows.Foundation. IAsyncOperationWithProgress<Windows.Web.Syndication.SyndicationFeed, Windows.Web.Syndication.RetrievalProgress. So, I tried using SyndicationFeed feed and it worked but now the content of the item is not retrievable via item.Text. There is a node value instead but it contains all the text not just what I need

i3arnon Over a year ago

@TamaraCaligari You should use the specific type that RetrieveFeedAsync returns. It seems like you have a "using" problem, so try using the full qualified name.

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