Controls to hold class objects

[hbrems]

Suppose I create a number of clsEmployee objects from a recordset. Great! Now I can loop through the employees.

Dim employee As clsEmployee
dim employees as Collection

... recordset loads employees in collection ...

For Each employee In employees
     listbox.AddItem employee.ID & ";" & employee.Name
Next

As you can see I've stored the employee property values in a listbox. However, are there any controls in Access that can hold actual objects iso just the values?

 

[vbaInet]

1. Set a new collection
2. Add the instance of clsEmployee to the collection (after adding to the properties of clsEmployee of course)

I would imagine there's some more information about this on the net

 

[stopher]

As you can see I've stored the employee property values in a listbox. However, are there any controls in Access that can hold actual objects iso just the values?

I assume you mean make a collection the source for the control(?) I'm not aware of any standard controls where you can do this.

I can understand why you would want to do this. However, I think technically it would be quite challenging (at least in Access). The reason I think this is because when using a recordset or query as a source, the source structure is very defined. However, if you were to use a collection of objects, how would the control know the accessor methods for the objects or which methods to use/not use? I suppose it's possible though. But Access is a database front end so it would then beg the question why use an object approach?

Chris

 

[hbrems]

Why use an object approach?

Why not use an object oriented approach? A database is a structured way of storing data, OOP is a structured way of programming. VBA is limited on the OOP front but its classes still allow me to create a more natural feel for the data I'm working with.

Personally I don't like to work with tables or queries as rowsource for my forms or controls. Here's the approach I'm currently using (which may be totally crazy to most Access programmers ):

1. A form requests from information from the database
2. A repository class will read the records from the table and create objects
3. These objects become available to the form

An example:

Public Sub btnPrintPayChecks_Clicked()

Dim employee As clsEmployee
Dim employees As Collection
Dim rep As clsEmployeeRepository

     set col = rep.ReadAllEmployees()
     
     for each employee in employees
          employee.PrintPayCheck
     next

End sub

 

[vbaInet]

I see what you're doing.

Disadvantage: In a multi-user environment, when changes are made to that record on table-level it will not reflect on what the class contains.

 

[hbrems]

In a multi-user environment, when changes are made to that record on table-level it will not reflect on what the class contains.

That's a valid point. In cases where the most recent information is needed I'll need to refresh the data contained in the object.

 

[vbaInet]

I suppose naturally you would want the most recent records from a domain. Having to refresh a large set of records will be double work when you can have recordsets and bound forms that already do this for you.