MS Access : Determine Object Type

问题:

Is there a way to determine the Object type, when passing a reference to a function?

I'm using a security permissions function, which determines if the user has permission to view/edit the Form passed to it by reference. I'd like to expand this to include reports as well.

To keep the function generic, I'd like to pass a ref for either a Form or a Report as an Object, eg: function gfSecurity_Permission(obj as Object)

However, I'd need to determine the type of the object within the function.

Does anyone know of a way to do that?

MTIA

回答1:

Take a look at

typeOf and typeName

Generic object variables (that is, variables you declare as Object) can hold objects from any class. When using variables of type Object, you may need to take different actions based on the class of the object; for example, some objects might not support a particular property or method. Visual Basic provides two means of determining which type of object is stored in an object variable: the TypeName function and the TypeOf...Is operator.

TypeName and TypeOf…Is
The TypeName function returns a string and is the best choice when you need to store or display the class name of an object, as shown in the following code fragment:

Dim Ctrl As Control = New TextBox  
MsgBox(TypeName(Ctrl))

The TypeOf...Is operator is the best choice for testing an object's type, because it is much faster than an equivalent string comparison using TypeName. The following code fragment uses TypeOf...Is within an If...Then...Else statement:

If TypeOf Ctrl Is Button Then  
    MsgBox("The control is a button.") 
End If

回答2:

Simplest way to determine the access type in access is to do an object lookup within the Access' system tables.

Here would be the lookup:

DLookup("Type","MSysObjects","NAME = '" & strObject & "'")

strObject is the name of the object within Access

The result is one of the number below OR NULL if the object does not exist in Access

1 = Access Table
4 = OBDB-Linked Table / View
5 = Access Query
6 = Attached (Linked) File  (such as Excel, another Access Table or query, text file, etc.)
-32768 = Access Form
-32764 = Access Report
-32761 = Access Module

so, the dlookup would provide "-32768" for a Form or "-32764" for a Report Hope that helps