Sometimes certain subscriptions will contain a mixture of articles, some that you're interested in, and some that aren't of any interest. FeedGhost allows you to 'filter' subscriptions so that only those articles of interest appear. As examples, I'm going to filter the example "Simply Recipes" subscription to show only certain dishes, and the "Rotten Tomatoes" subscription to show only top-rated movies.
To access the filtering functionality for a subscription, right-click it in the tree and choose "Edit".
Choose the "Filter" tab of the "Edit Subscription" dialog that appears.
If the text area is empty, FeedGhost doesn't apply a filter — all articles will be displayed. Entering a filter expression however will cause FeedGhost to only display articles that match the given expression — articles that don't match are completely discarded.
Although the regex (regular expression) syntax used by the filtering feature can be complex, the easiest case is just to enter a word in the filter box — only articles containing that word will then be displayed.
For example, if I enter the word:
chicken
into the filter box, and click "OK", the subscription will be filtered so that only articles involving "chicken" are ever displayed.
Of course, if you want to stop filtering a subscription, just delete the text in the "Filter" tab, and click "OK". The subscription will be refreshed, and the old articles will re-appear.
Often you'll want to display feeds that match a range of words — this OR that OR another. To achieve this, use the vertical bar symbol to separate words. For example,
chicken|lamb|beef
keeps any articles that contain any of the words "chicken", "lamb", or "beef".
More advanced filters can be constructed to use the full power of regex expressions. If you need to go beyond the simple filters described above, or if you find errors appearing, you may find the expression builder helpful. Click the ellipsis button ("...") to the right of the text box to launch this.
The text box at the top of the dialog is exatcly the same as the one in the "Edit Subscription" dialog. The bottom area allows you to enter test text to see if it matches or not.
As an example, I'll demonstrate a filter that only displays high-rated movies on the "Rotten Tomatoes" subscription. I'm going to filter this feed so that only movies rated 70% or higher appear.
I can see that this subscription includes the rating in the title, so I can match on that. First of all, I'll handle films rated 70%-99%. The match criteria for these films is a number 7,8, or 9, followed by a number 0..9, followed by a percentage sign. I can match these character ranges using square brackets, as follows:
[7-9][0-9]%
Of course, I haven't matched films rated 100% yet, but I can do this by applying an "OR" expression. I use round brackets to group the expressions, giving:
([7-9][0-9]%)|(100%)
Once this filter is applied, I now only see movies rated 70% or above:
For more information on regular expressions, please see ".NET Framework Regular Expressions".