Saving State

Posted on 2001-09-17
Last Modified: 2010-05-02
In VB, how do do I save the state of a form?  For example, I have several forms that a user can progress through.  The problem I am having is when the user clicks 'Cancel' on a particular screen.  When this happens I want to redisplay the previous screen with all the same settings the user selected.  Currently, I am using the registry to keep track of state information.  Is this the best way?  What are my options?  Some example code or internet documentation would be very helpful.  Thanks.
Question by:hotwheels
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Expert Comment

ID: 6487794
The registry is NOT the place to keep track of selected values, use variables, Whe are talking VB right not ASP webpages? If VB it is, you can easely collect the selected info in global variables of your main form.

An other option is to make all form layouts in the same form and then hide/display the right layout while progressing, this way you only have to collect the info at the end, and all settings are maintained until the user closes the form or clicks the final finish button.

This sollution, is more design intensive but much neater then yours, and it is how setup forms (tab forms) work

Expert Comment

ID: 6487798
can you use form.visible = false to hide previous screens?
and form.visible = true to show

Expert Comment

ID: 6487874
rkot2000 has the better answer here. Global variales are generally discouraged if you can use a lesser scope to do the job (ie form or procedure level variables) Simply hiding a form will retain all listbox selections, textbox valus, etc. They'll still be there when you show the form again. If you're holding info in form level variables, be aware of this:

If you use syntax like
'set some form level vars
''''more stuff
unload form1

when you do a again, he form level vars will still hold the vals you set before you unloaded (sounds like you may want to use this to your advantage)

in contrast, the following will not retain values from to the next.

Dim myForm as form1
Set myForm = new Form1

'set vals
unload myform

Set myForm = new Form1
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Expert Comment

ID: 6488001

Firstly , Storing settings in registry may be right choice if no of settings is limited.

By the way - do you want values to persist even when user has closed application ?

or Is it that you just want to maintain state for current session ?

LVL 52

Expert Comment

by:Ryan Chong
ID: 6489286
Hi hotwheels,

Depends on what you need in your application.

Keeping the values in registry is a choice, alternatively you can also store the values in a INI file, or use a normal file that you can define the method to read/ write from it.

Using registry is good as its location never changed.


Expert Comment

ID: 6489897
Use the registry only for settings you want to maintain even after software is close, pc is rebootde, etc. but for a current sellection, and therefor var's wich are only used temperorly and is not the right way to go.

I agree with rkot2000 as it is like i stated as seconde and more preferable sollution in my first post, hiding/showing layouts is better.
LVL 52

Expert Comment

by:Ryan Chong
ID: 6490045
> hiding/showing layouts is better
Only when few forms are loaded or in a small application bcos memory will be loaded as forms are loaded..

Accepted Solution

telebasics earned 75 total points
ID: 6490094
well, these are the sollutions, looks like it is a personal choice what is better, i personaly try to keep the registry as clean as i can.

btw, you can use multiple "forms" in one form object, like using the tab control, on form holds many, wich all get hidden and only the one you want to show gets shown, one piece of memory, and when your totaly done unload the form and memory is free, dont forget to save ;-)

Author Comment

ID: 6490798
All of these suggestions are great!  I am real busy right now, and it will take me some time to test out the solutions.  I only need the variables during the current session.  However, the memory use is a large factor.  Thank you all very much for your comments.  I will assign points within two weeks.

Expert Comment

ID: 6490903

If you need to save state for current session,then you might like to add properties to FORM, similar to classes Let/Get

Hope this Helps

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