IWMPMediaCollection::getByAttribute method (wmp.h)

[アーティクル]
4/26/2023

[The feature associated with this page, Windows Media Player SDK, is a legacy feature. It has been superseded by MediaPlayer. MediaPlayer has been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer instead of Windows Media Player SDK, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The getByAttribute method retrieves a pointer to an IWMPPlaylist interface. This interface corresponds to the specified attribute having the specified value.

Syntax

HRESULT getByAttribute(
  [in]  BSTR         bstrAttribute,
  [in]  BSTR         bstrValue,
  [out] IWMPPlaylist **ppMediaItems
);

Parameters

[in] bstrAttribute

String containing the specified attribute.

[in] bstrValue

String containing the specified value.

[out] ppMediaItems

Pointer to a pointer to an IWMPPlaylist interface for the retrieved media items.

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code	Description
S_OK	The method succeeded.

Remarks

This method can be used to create a generic query for media items that match a value for an attribute in the database. This is useful in the case of user-defined attributes. If the attribute does not exist, an error will result.

You can use this method to retrieve all of the media items of a specific type. Use the attribute name "MediaType" and one of the following values:

Value	Description
audio	Music and other audio-only items
other	Other items, such as an .asf file or the URL of a stream.
photo	Photo items. Requires Windows Media Player 10.
playlist	Playlists represented as media items.
radio	Radio station items. Not used by Windows Media Player 10.
video	Video items.

Before calling this method, you must have read access to the library. For more information, see Library Access.

There are two ways you ways you can retrieve an IWMPMediaCollection interface, and the behavior of the getByAttribute method depends on which of those two ways you use. If you retrieve the interface by calling IWMPCore::get_mediaCollection, then the getByAttribute method returns all the media items in the library that have the specified attribute and value. If you retrieve the interface by calling IWMPLibrary::get_mediaCollection, then the getByAttribute method returns only the audio items in the library that have the specified attribute and value.

Requirements

Requirement	Value
Minimum supported client	Windows Media Player 9 Series or later.
Target Platform	Windows
Header	wmp.h
DLL	Wmp.dll

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