SHAddDefaultPropertiesByExt function (shobjidl.h)

Article
10/13/2021

Adds default properties to the property store as registered for the specified file extension.

Syntax

SHSTDAPI SHAddDefaultPropertiesByExt(
  [in] PCWSTR         pszExt,
  [in] IPropertyStore *pPropStore
);

Parameters

[in] pszExt

Type: PCWSTR

A pointer to a null-terminated, Unicode string that specifies the extension.

[in] pPropStore

Type: IPropertyStore*

A pointer to the IPropertyStore interface that defines the default properties to add.

Return value

Type: HRESULT

If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

The list of properties used to set a default value comes from the SetDefaultsFor registry value of the ProgID for the file association of the specified file extension. The list is prefixed by "prop:" and contains the canonical names of the properties to set the default value, such as: "prop:System.Author;System.Document.DateCreated". The possible properties for this list are System.Author, System.Document.DateCreated, and System.Photo.DateTaken. If the SetDefaultsFor value does not exist on the ProgID, this function uses the default found on the SetDefaultsFor value of HKEY_CLASSES_ROOT*.

System.Author has the value of the user that performed the action. System.Document.DateCreated and System.Photo.DateTaken use the current date. These three properties are the only ones for which the system provides special defaults.

Note that there are several types of properties:

Properties that derive from the file system (such as, size and date created)
Properties that derive from the file (such as, dimensions and number of pages)
Properties that are placed in the file (such as, author and tags)

When creating a new file, types one and two are provided just by creating the file. But properties of type three must be set explicitly by a program. The system provides SHAddDefaultPropertiesByExt to provide values for up to three specific properties of type three. Sometimes Windows Explorer uses this API when saving a file for the first time, or when creating a new file after the menu choice New is selected from a shortcut menu.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
Target Platform	Windows
Header	shobjidl.h
DLL	Shell32.dll

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