Optimization Using GetInfoEx

The IADs.GetInfoEx method is used to load specific attribute values into the local cache from the underlying directory service. This method only loads the specified attribute values into the local cache. The IADs.GetInfo method is used to load all attribute values into the local cache.

The IADs.GetInfoEx method gets specific current values for the properties of an Active Directory object from the underlying directory store, refreshing the cached values.

If a value already exists in the property cache, however, calling the IADs.Get or IADs.GetEx method without first calling IADs.GetInfoEx for that attribute will retrieve the cached value rather than the most current value from the underlying directory. This can cause updated attribute values to be overwritten if the local cache has been modified, but the values have not been committed to the underlying directory service with a call to the IADs.SetInfo method. The suggested method for avoiding caching problems is to always commit attribute value changes by calling IADs.SetInfo before calling IADs.GetInfo.

Dim usr As IADs
Dim PropArray As Variant

On Error GoTo Cleanup

' Bind to a specific user object.
Set usr = GetObject("LDAP://CN=Jeff Smith,CN=Users,DC=fabrikam,DC=com")
 
' The code example assumes that the property description has a single value in the directory.
' Be aware that this will implicitly call GetInfo because, at this point, GetInfo
' has not yet been called (implicitly or explicitly) on the usr object.
Debug.Print "User's common name is " + usr.Get("cn")
Debug.Print "User's title is " + usr.Get("title")
Debug.Print "User's department is " + usr.Get("department")

' Change two of the attribute values in the local cache.
usr.Put "cn", "Jeff Smith"
usr.Put "title", "Vice President"
usr.Put "department", "Head Office"
Debug.Print "User's common name is " + usr.Get("cn")
Debug.Print "User's title is " + usr.Get("title")
Debug.Print "User's department is " + usr.Get("department")

' Initialize the array of properties to pass to GetInfoEx.
PropArray = Array("department", "title")
 
' Get the specified attribute values.
usr.GetInfoEx PropArray, 0

' The specific attributes values were overwritten, but the attribute
' value not retrieved has not changed.
Debug.Print "User's common name is " + usr.Get("cn")
Debug.Print "User's title is " + usr.Get("title")
Debug.Print "User's department is " + usr.Get("department")

Cleanup:
    If (Err.Number<>0) Then
        MsgBox("An error has occurred. " & Err.Number)
    End If
    Set usr = Nothing

Retrieving Active Directory Constructed Attributes

In Active Directory, most of the constructed attributes are retrieved and cached when the IADs.GetInfo method is called (IADs.Get performs an implicit IADs.GetInfo call if the cache is empty). Some constructed attributes, however, are not automatically retrieved and cached and, therefore, require that the IADs.GetInfoEx method be called explicitly to retrieve them. For example, in Active Directory, the canonicalName attribute is not retrieved when the IADs.GetInfo method is called and IADs.Get will return E_ADS_PROPERTY_NOT_FOUND. The IADs.GetInfoEx method must be called to retrieve the canonicalName attribute. These same constructed attributes will also not be retrieved using the IADsPropertyList interface to enumerate the attributes.

For more information and a code example that shows how to retrieve all attribute values, see Example Code for Reading a Constructed Attribute.