[AccessD] Your favorite control behavior

Arthur Fuller artful at rogers.com
Sun Mar 7 13:14:12 CST 2004 

I don't see the advantage to doing it in the OnOpen versus in the
NotInList event of the control itself. Either way it's one line of code.
Please explain.

Arthur

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of John W. Colby
Sent: Sunday, March 07, 2004 4:56 AM
To: Access Developers discussion and problem solving
Subject: RE: [AccessD] Your favorite control behavior


>That is almost exactly the way my Notinlist procedure is coded.  I also

>add
two parameters, one for the target table to which the record will be
added and one for a user name for the type of data to be added.

My framework has this functionality built in.  The developer programs
the framework for each such control in the form's OnOpen with syntax
like:

    With fclsfrm.Children
        .Item("cboIDCity").NotInListData "tlkpCity", "CI_Name",
"lfrmCity"
        .Item("cboIDPrefix").NotInListData "tlkpPrefix", "PFX_Prefix",
"lfrmPrefix"
        .Item("cboIDSuffix").NotInListData "tlkpSuffix", "SFX_Suffix",
"lfrmSuffix"
        .Item("cboIDCity").DependentSet
fclsfrm.Children("cboIDContactCity")
        .Item("cboIDST").DblClickFormData = "lfrmState"
        .Item("cboIDContactCity").NotInListData "tlkpCity", "CI_Name",
"lfrmCity"
        .Item("cboIDContactSt").DblClickFormData = "lfrmState"
        .Item("cboIDContactCity").DependentSet
fclsfrm.Children("cboIDCity")
    End With

This is actual code taken from the Open of a form in an application.
You can also see the calls to set up "dependent object processing" for
combos that have other combos that need requerying when they are
changed.

For the NotInList processing, as you can see I specify the combo name to
find the class for in a collection of classes - .Item("cboIDCity"), then
specify a method of that class that I will pass parameters into -
.NotInListData, then pass in the table name, field name, and a form to
open if the double click is used.  If the form is missing, the double
click is disabled.  If the table and field are missing but the form is
there, then the NotInList is disabled.  There are tables that a combo
can display data from that have multiple fields that may need editing.

In addition, my code that opens the form takes the PK of the item
currently selected and looks up that record, so that when the form opens
it is already on that record waiting to be edited.

>I just set a single record recordset for the existing form to the 
>record
that is added and it displays the new data in the appropriate field or
fields.

I tried doing multi-field parsing and such and it just got too messy and
confusing to the user.  If the table has multiple fields, I open an edit
form, take the data the user just typed that wasn't in list and make
that data the "default value" of the control on the form for the data
displayed in the combo.  For example if the user is typing in an SSN of
a person ad it is not in list, there are waaaay to many fields to fill
in for a new person to just do it without a form, so I open the form in
Add mode, and place that SSN in the ssn field on the form.

This is all done using the combo control class communicating with the
form class.  The control class opens the new form and passes in
OpenArgs.  The form class discovers it has openargs, loads an OpenArgs
class which parses the OpenArgs and processes any standard OpenArgs such
as the one to find the control and make the data the DefaultValue.

>in the On Got Focus entry in the property you could enter:
=OnFocus([Screen].[Activecontrol])

Unfortunately doing things that way has several major drawbacks.

1) You can't use the Find in a code module to find everywhere that
function is called since the call to the function isn't in code.  I
realize that it can be found from a search utility such as speedferret
or Find and Replace but that means that you now have to switch focus and
go to that utility.

2) You can't add other functionality to that event since you are
specifying that YOUR function be called.  There is no generic event stub
for adding additional processing to.

3) Programs such as my framework which need to hook events just write
MyCtl.SomeEvent = "[EventProcedure]" in order to hook the event and
cause Access to route processing to the event stub.  Your custom
processing would just disappear now.

Using this method is fine if you are the only developer who will ever
touch your app (and unfortunately many developers simply don't care
about the guy that comes along behind).  You know you do that, you love
doing that and you are happy with it.  God forbid you get hit by a bus
and I have to take over maintenance of your app because I will be
cursing your name for the rest of the life of that application (or until
I get the mess straightened out).

>Another nice means to hookup events automatically is to create a 
>control
combination, or even a single control, encapsulated on a sub form all by
itself.

My only problem with using subforms in this manner is the frustration of
getting the cursor movement to work correctly.  The user is tabbing
along filling in data and hits a subform and has to then use special
keys to get out of the thing and into the next control to be filled in.
A custom class that has all the required processing that your form class
has gives me all
(most) of the advantages that you mention without the "cursor movement"
issues since the control is now in my main form.  The only thing I don't
get is the "drag and drop and I'm done".  I do have to dimension the
class, initialize it, and clean it up when I am done.  I am so used to
using classes now though that this is a 60 second thing.

On the other hand, if this really is so generic that I use it all the
time, I use a naming convention such that as a combo or list class loads
it looks at it's name and hooks in the calls to that class to do the
special processing for it.  Then you are right back to drag and drop
convenience.  I do this for the record selector combos at the top of my
forms.  They use a naming convention and my combo class just "knows"
that this is a record selector and when an item is selected in that
combo the combo class finds the record selected and causes the form to
display it.

John W. Colby
www.ColbyConsulting.com

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com]On Behalf Of Jürgen Welz
Sent: Sunday, March 07, 2004 1:09 AM
To: accessd at databaseadvisors.com
Subject: RE: [AccessD] Your favorite control behavior


That is almost exactly the way my Notinlist procedure is coded.  I also
add two parameters, one for the target table to which the record will be
added and one for a user name for the type of data to be added.  I guess
the only difference is that I don't open a separate data entry form.  I
just set a single record recordset for the existing form to the record
that is added and it displays the new data in the appropriate field or
fields.

For things like date fields or lookups, I create them once on a template
form and then copy from there to the form on which I need it displayed.
Although you can use WithEvents and hook up controls, I haven't found a
way to do this with the Notinlist parameters.  I have found that just
about every event that I may want to use WithEvents for, I can instead
create a public function procedure for.  For a control that displays a
date for which I want a calendar to pop on double click and to change
backcolor when it gets focus and revert to a non-focus backcolor when
focus is lost, or respond to mouse move events, I can call the public
procedure, usually passing in screen.activecontrol by using the function
name rather than [eventprocedure] in the property sheet.  When I copy
and paste a date control from my template form into a new target form,
it is completely hooked up to all standard events.  Retrieving the form
container name only requires the code to check the parent property of
the active control.  For example, if you open the event property sheet
for a conventional textbox, in the On Got Focus entry in the property
you could enter:

=OnFocus([Screen].[Activecontrol])

and in the On Lost Focus entyr you could enter:

=OffFocus([Screen].[Activecontrol])

Then in a public module:

Public Function OnFocus(ctl As Control)
    ctl.BackColor = vbWhite 'or some standard constant
End Function
Public Function OffFocus(ctl As Control)
    ctl.BackColor = -2147483633 'or some constant that can be set End
Function

You can check for control type being a combo and call .DropDown in the
OnFocus or write a separate OnFocusCombo procedure.  The whole point is
that the event procedures are hooked up  when you paste a copy of the
control as the event properties are copied with the control.

Another nice means to hookup events automatically is to create a control
combination, or even a single control, encapsulated on a sub form all by
itself.  The control comes with its own class module in the code behind
the subform.  I have found this a great way to hookup something like a
callback based list of municipalities with a not in list that can be
made aware of the need to requery the data array when there is an
addition or change to a municipality record.  No need to create a new
copy of the control on multiple forms, just drag the subform container
on and you get format and events all done.

Ciao
Jürgen Welz
Edmonton, Alberta
jwelz at hotmail.com





>From: "Arthur Fuller" <artful at rogers.com>
>Reply-To: Access Developers discussion and problem 
>solving<accessd at databaseadvisors.com>
>To: "'Access Developers discussion and problem 
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>Subject: RE: [AccessD] Your favorite control behavior
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>I have a function called aaNotInList() which takes the same parms as 
>the NotInList function and adds two new ones -- the name of the form to

>open when adding an item, and the "human" name of said entity, the 
>latter just to pretty up the messagebox that comes up. The functon asks

>if you want to add a new "XXX" (4th parm) and if so opens the specified

>form, which uses the typical code to hide itself on OK and close itself

>on Cancel. Then the function does the usual "add to list and accept the

>value" and closes the form. It works great but I still have to type in 
>that line of code every time I need one. Not that one line of code is a

>major hassle, I guess, but can you think of a class-based way to do 
>this? It might be more fun to do it that way.
>
>Arthur
>
>-----Original Message-----
>From: accessd-bounces at databaseadvisors.com
>[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of John W. 
>Colby
>Sent: Saturday, March 06, 2004 1:24 PM
>To: AccessD
>Subject: [AccessD] Your favorite control behavior
>
>
>I am taking suggestions for control behaviors that you have found 
>useful and have programmed controls to perform in the past.
>
>For example I program the back color of combos, lists and text boxes to

>change to a given color as they get the focus, and back to their 
>original color as they lose the focus.  This helps to avoid the 
>"where's the cursor" questions.
>
>Another example, I program the double-click of a combo to open a form 
>to allow editing the data in the table that the combo pulls from.  In 
>addition, if a combo is programmed to perform this behavior, I 
>dynamically set its label's back color to a specific color.  this is a 
>visual cue that "this combo has the dbl-click behavior activated"
>
>What kinds of things do you have your controls do?
>
>John W. Colby
>www.ColbyConsulting.com
>
>
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