Scripting Parameters

Now that the holidays are over, time to get some work done again.

I’ve been rewriting some older scripts recently (again), and a lot of them are prompting the modelers for values to be used in the scripts.  I used to do this with a dialog box but now that PowerDesigner has forms, I’ve moved almost exclusively to extended attributes and forms.  This gives me a lot more control over the form, and allows me to gather multiple parameters at the same time.  It gives me greater control over lists of values, and it allows a script to “remember” the values chosen last time the script was run.

Let’s say I want to control access to the tables in my model through views.   Within a model, there are three parameters I want to control for my view generation:

1. Who owns the view
2. Do I use a view suffix (and what is it)
3. Do I want them placed on the diagram after they’ve been created

I could prompt the user three times, but that’s not terribly user friendly.  I’m also very likely to regenerate or add new views over time, and I’ll likely want the same settings each time.

So, instead of prompting for each option individually, I’m going to create an extended attribute for each and a popup form that the user can use to set the values.

Creating the Extended Attributes

First, we create the three extended attributes we’ll use to control our script. Notice that I’ve created a category to keep them organized.  I’ll create the same category for forms, templates etc. so it’s easy to see what’s related.

I’ve created “Place Access View On Diagram” as a boolean, and “Access View Suffix” as a string.  “Access View Owner” needs to be a user defined in the model, so I’ve created it as a text attribute with a list of values.  You can do this by clicking on the “Create” button next to the List of values: box on the attribute.  When the template definition box pops up, enter this code in the editor:

.foreach_item (Model.Users)
%Name%
.next (\n)

This creates a new template called “access View Owner List”.  I recommend you immediately go in, create your category, and then move the template into it for organizational purposes.

Adding the Form

Now that we have our attributes, we need a way to set them (duh).  So let’s make a form.  Create our category, create our blank form, set it as a dialog box, and use the “Add Attribute” button to add our new extended attributes.  Our extended model definition now looks like this:

Setting Parameters

Now we’ve got our extended attributes, and our form.  We need a script with a few extra lines.  Since the point of this post is parameters, not views, I’ve condensed everything but the dialog down to  a couple of dots.

So here’s our script:

Dim dlg

…

Set dlg = obj.CreateCustomDialog(“Access Control Views”)
If not dlg is Nothing Then
dlg.ShowDialog()
End If

…

And here’s the result:

Now that we’ve set the values, we need to get them for the script:

owner = obj.getExtendedAttributeText(“Access View Owner”)

suffix = obj.getExtendedAttributeText(“Access View Suffix”)

display = obj.getExtendedAttributeText(“Place Access View on Diagram”)

Done.  Now the user only has to set the values the first time the execute the script or if they change the values and you can see what values were chosen by looking at the extended attributes.

Next time, we’ll expand on this a bit with some additional options to make this more flexible.

Selection Goodness

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:

• AddActiveSelectionObjects
• ShowObjMultiSelection
• ShowObjectPicker

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.

Missing Timestamps and AltEnableTSCopy

I’m working on a deploy for an Oracle (10g) database and I’ve been asked to preserve data. Because most of my tables are compressed I’ve got “use alter when possible” disabled (that and the fact that you rarely get alters anyway but that probably deserves its own post someday). So, PowerDesigner does this:

1. Rename the original table to “tmp_Table”
2. Create the new table
3. Insert into table (col1, …, colN) select col1, …, colN from “tmp_Table”

When I test the script, I discover that my audit columns (“Created Datetime”, “Last Update Datetime”) are missing from my insert statements. No errors reported. No warnings.  No question marks for me to find and fix.  They’re just not there.  This seemed a bit unusual.

Turns out there’s an option in the XDB file that allows you to skip timestamp columns when you reload the table.  Probably handy, but not what I want.  More interesting, the default is set to omit them.  Even more interesting, the option is hidden when you look in the XDB file.  I’m assuming the thinking is that timestamp columns will be populated with defaults (or by trigger) when the data is re-inserted but, in this case, I don’t want my table alterations to change the audit trail information in the table and it seems a bold assumption that all of your timestamp columns are audit trail data anyway.

To change the value, you need to go to Edit Database\Script\Objects\Column then right click on table and select “Add Items”.

Scroll through the list of options that we apparently don’t need to know about and  find AltEnableTSCopy.

Add it to the list of options, and then change the default from 0 (skip timestamp columns) to 1 (copy timestamp columns).  You should now see your timestamp columns included in your insert statements.

I think this behavior is really poorly thought out.

1. The default should be to include all columns in the insert statement rather than omitting them
2. If you’re going to have the default be to omit columns from an insert statement, the parameter to configure this should really be visible without having to go in and manually add it.

I did take a few minutes to peak at the rest of the hidden options in the column and table objects in the XDB file and some of them appear quite useful.  I hope to complete a more thorough review in the future.  If I find anything interesting, I hope to post it here.