Today’s post is on selections. Selections are a great way to script changes to multiple objects and a great way to make your custom methods more flexible.
Selections are just what they sound like, a group of objects, placed into a collection for processing. Let’s jump right in with a simple example:
Dim mySel Set mySel = ActiveModel.CreateSelection mySel.AddObjects ActiveModel, cls_table, false, true
The first two lines declare and create your selection. The third line adds all objects of the given class, in this case tables, to the selection. The last two parameters (false, true) tell the script to skip shortcuts and to recurse through sub-packages. Now that we have our selection, how do we use it. The following lines will loop through the collection. For my examples, I’m using SetNameAndCode to rebuild the codes on all the objects in the selection, just to demonstrate the concept.
Dim myObj Dim mySel Set mySel = ActiveModel.CreateSelection mySel.AddObjects ActiveModel, cls_table, false, true For each myObj in mySel.Objects With myObj Output .Name .SetNameAndCode .Name, "", True end with Next
So far, so good. It gets better though. You’re not restricted to a single class in a selection. So if you’d like to rebuild the codes for both tables and views, you can add both classes. Our revised code looks like:
Dim mySel Dim myObj Set mySel = ActiveModel.CreateSelection mySel.AddObjects ActiveModel, cls_table, false, true mySel.AddObjects ActiveModel, cls_view, false, true For each myObj in mySel.Objects With myObj Output .Name .SetNameAndCode .Name, "", True end with Next
Without a selection, we’d be stuck doing something like:
For each tab in ActiveModel.tables Output tab.Name Tab.SetNameAndCode Tab.Name, "", True Next For each view in ActiveModel.views output view.name view.SetNameAndCode view.Name, "", True Next
That’s not too bad, but notice our SetNameAndCode sample is very short. Also, we’re only dealing with two classes and we’re only dealing with objects in the root of the model. If we want to recurse through packages, there’s a lot of additional work yet to be done.
Now, suppose we don’t want to include all objects of a particular class, but we’d like to be a bit more choosey. We have a couple of options:
The first, AddActiveSelectionObjects method, does exactly what it says it does. Whatever objects you currently have selected, either in the browser or the active diagram are added to your current selection. I’ll focus on the other two.
The second two provide dialog boxes which you can use to define your selection manually.
Here’s an example:
Dim mySel Set mySel = ActiveModel.CreateSelection mySel.ShowObjMultiSelection ActiveModel, "Tables"
The first parameter is the name of the parent object. In this case, the active model. The second parameter, this case “Tables” is the name of the collection you want to select from. You’ll get a dialog that looks like this:
Choose the objects you want and processing using the same select loop. Instead of the active model, the first parameter can be changed a particular table, view, etc. This allows you to choose from objects that apply only to that object. This is very handy in a custom method. For example, this method would allow you to select references on a particular table. Keep in mind that the selection itself is still a property of the model, not Obj.
Sub %Method%(obj) dim mySel dim myObj Set mySel = ActiveModel.CreateSelection mySel.ShowObjMultiSelection Obj, "InReferences" for each myObj in mySel.Objects With myObj Output .Name .SetNameAndCode .Name, "", True end with next End Sub
If you’ve looked at the VBScript help file, you probably know there’s a great example of how to build your own custom selection list for the multi-selection method. I’m going to change it just a bit to show you how to get a single selection dialog with both inReferences and outReferences. This also demonstrates the Add method available to any collection.
Sub %Method%(obj) dim myObj dim ref'add all of the objects we’re interested in to the collection Set mySel = ActiveModel.CreateSelection For each ref in Obj.inReferences mySel.Objects.Add(ref) next For each ref in Obj.outReferences mySel.Objects.Add(ref) next 'now show the objects in the selection in your dialog mySel.ShowObjMultiSelection mySel, "Objects" for each myObj in mySel.Objects With myObj Output .Name .SetNameAndCode .Name, "", True end with next End
The other method of adding objects to a selection, SubShowObjectPicker, behaves quite a bit differently. I don’t use this method nearly as often, but we’ll cover it just for completeness.
Unlike the mult-selection dialog, ShowObjectPicker always (as far as I can tell) starts from the active model. You can choose which class of object the user gets to choose from (e.g. tables or columns) but you can’t choose to show only columns belonging to a specific table. You can filter by stereotype but unless you’re going to change the stereotype for an object at runtime (and set it back when you’re done), this isn’t an approach I find particularly useful. Anyway, here’s a code snippet and the result.
Dim mySel Set mySel = ActiveModel.CreateSelection mySel.ShowObjectPicker "Table:Column"
This gives you the following dialog:
Well, that’s enough for now. More to come.