View source for Documentation:WindowsFileFilter

You can control which files a user sees in the WPF file-open dialog for a blob column by setting the <code>WindowsFileFilter</code> tagged value on a [[Documentation:ViewModel Editor|ViewModel]] column that uses a BlobField.

== Use WindowsFileFilter ==
In WPF, add the <code>WindowsFileFilter</code> tagged value to a <code>ViewModelColumn</code> whose field is a BlobField. The value influences the files shown by the file-open dialog when the user selects a file for that column.

# Open the ViewModel that contains the BlobField column.
# Select the <code>ViewModelColumn</code> for the BlobField.
# Set the <code>WindowsFileFilter</code> tagged value to the file filter you want to use.
# Run the WPF application and open the file dialog for the column to verify the displayed file types.

For example, to present an image-file choice for a blob column, use:

<syntaxhighlight lang="text">
Image files (''.jpg, ''.jpeg, ''.jpe, ''.jfif, ''.png, ''.gif) | ''.jpg; ''.jpeg; ''.jpe; ''.jfif; ''.png; ''.gif
</syntaxhighlight>

== Default behavior ==
The default filter depends on the BlobField's blob type.

{| class="wikitable"
! BlobField blob type
! Default file filter
|-
| <code>Image</code>
| <code>Image files (''.jpg, ''.jpeg, ''.jpe, ''.jfif, ''.png, ''.gif) | ''.jpg; ''.jpeg; ''.jpe; ''.jfif; ''.png; ''.gif</code>
|-
| Any blob type other than <code>Image</code>
| Blank; all files are shown.
|}

== Example ==
Assume that a ViewModel has a BlobField column for a product photograph. If the blob type is <code>Image</code>, the file-open dialog uses the image-file filter by default. If you set <code>WindowsFileFilter</code> on that column, the tagged value controls the filter shown for that column instead.

For a BlobField that is not an <code>Image</code>, no default filter is supplied. Set <code>WindowsFileFilter</code> when you want the file-open dialog to present a specific filter rather than showing all files.

== Scope ==
<code>WindowsFileFilter</code> is described for WPF and affects the file-open dialog used for a BlobField in a ViewModelColumn.

== See also ==
* [[Documentation:ViewModel Editor]]

[[Category:Desktop UI (WPF/WinForms)]]
[[Category:Intermediate-Friendly]]
[[Category:Priority 50]]
[[Category:UI & Styling]]
[[Category:WPF UI with MDriven (WECPOF)]]