MICROSOFT_PRESS_EBOOK_PROGRAMMING_WINDOWS_8_APPS_WITH_HTML_CSS_AND_JAVASCRIPT_PDF

When the query is built through a method like createFileQueryWithOptions, the application and
user filter strings here are combined. What this means is that you can separately manage any filter you
want to apply generally for your app (applicationSearchFilter) from user-supplied search terms
(userSearchFilter). This way you can enforce some search filters without requiring the user to type
them in, and without always having to combine strings yourself.
As noted before, the CommonFileQuery.orderBySearchRank query is meaningful only when combined
with an AQS string, which is to say that keyword-based searches return ranked results for which this
common file query would apply. Returning to Scenario 1 of the Programmatic file search sample, then,
we see how it uses this ordering along with the userSearchFilter property:
var musicLibrary = Windows.Storage.KnownFolders.musicLibrary;
var options = new Windows.Storage.Search.QueryOptions(
Windows.Storage.Search.CommonFileQuery.orderBySearchRank, ["*"]);
options.userSearchFilter = searchFilter;
var fileQuery = musicLibrary.createFileQueryWithOptions(options);
On my machine, where I have a number of songs with “Nightingale” in the title, as well as an album
called “Nightingale Lullaby,” a search using the string "Nightingale" System.ItemType: "mp3" in the
above code gives me results that look like this in the sample:
This shows that the search ranking favors songs with “Nightingale” directly in the title, but also
includes those from an album with that name.
My search string here, by the way, shows how you might use the applicationSearchFilter and
userSearchFilter properties together. If my app was capable of working only with mp3 or some other
formats, I could store "System.Item.Type: 'mp3'" in applicationSearchFilter and store user-provided
terms like "Nightingale" in userSearchFilter. This way I avoid having to join them manually in my
code.
Beyond the properties that you set within a QueryOptions object, it also has some information and
capabilities of its own. The groupPropertyName, for one, is a string property that indicates the type of
property that the query is being grouped by. You can also retrieve the query options as a string using
the saveToString method and recreate the object from a string using loadFromString (that is, the
analog of JSON.stringify and JSON.parse).
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