Need a variable to persist from database to database?

[jjfcpa]

Is there a variable declaration that will persist when opening a new database?

I am creating it in one database as a global variable, changing it in another database, but when I come back to the original database, it appears that the variable did not persist.

[Stan Mathews]

Re: Need a variable to persist from database to database?

I suppose there's a reason you don't want to use the help files?

Variable
-----Scope

Note the description of Addin variables

Also the "tutorial", Thanks Tom Henkel

[jjfcpa]

Re: Need a variable to persist from database to database?

After reviewing the documentation, I see that the Global variable only persists until the database is closed.

What is the recommended solution to pass a value back and forth when changing databases?

Can you pass a parameter to the autoexec script?

[jjfcpa]

Re: Need a variable to persist from database to database?

I suppose there's a reason you don't want to use the help files?

Variable
-----Scope

Note the description of Addin variables

Found it. Thanks for pointing my nose in the right direction.

If this forum wasn't so good, I'd probably rely on the help file a lot more. But I can typically post a question on here and get a response long before I can find it in the help file.

[Mike Wilson]

Re: Need a variable to persist from database to database?

John,

If this forum wasn't so good, I'd probably rely on the help file a lot more. But I can typically post a question on here and get a response long before I can find it in the help file.

Like most things, there is a learning curve to using the Help files, and after you use them and get used to using them, you will find it becomes significantly faster. For me, I forget most of what I learn and have to relearn it through re-looking up in the help files...... all the time! :(

[jjfcpa]

Re: Need a variable to persist from database to database?

I suppose there's a reason you don't want to use the help files?

Variable
-----Scope

Note the description of Addin variables

Also the "tutorial", Thanks Tom Henkel

I've run into another problem:

When the application starts and database 1 is opened, the following code is executed in the autoexec script:

dim c_do_what as P
c_do_what = addin.variables()
c_do_what.varname = "Startup"

I then change to database 2 and execute the following before returning to the 1st database:

dim c_do_what as P
c_do_what = addin.variables()
c_do_what.varname = "Relocate"


When I return to database 1, the c_do_what.varname has been successfully chanaged to "Relocate".

The problem is this. When the 1st database is opened, I only want to execute the line "c_do_what.varname = "Startup" if c_do_what.varname does NOT have a value; otherwise, I will change the value to Startup every time I return to database 1.

How do I evaluate c_do_what.varname to see if it has a value?

I tried eval_valid() and it errors out if it does not have a value, but has been dimensioned as a pointer variable.

[G Gabriel]

Re: Need a variable to persist from database to database?

John:
You lost me!
Seems like you are leaving out another peice of information.

1-When you open DB 1 you set c_do_what.varname to "Startup"
2-Then you go to DB 2 and set c_do_what.varname to "Relocate"
3-Then you go back to DB 1 where c_do_what.varname = "Relocate"
The question is, why didn't you set c_do_what.varname in DB 1 to "Relocate" in the first place?
Are you doing something in between?

But regardless, what you should do in DB 1 is:

if c_do_what.varname="" '[COLOR="Blue"]I don't see how this could happen 
unless as I said you are doing something in between.[/COLOR]
dim c_do_what as P
c_do_what = addin.variables()
c_do_what.varname = "Startup"
end if

[jjfcpa]

Re: Need a variable to persist from database to database?

John:
You lost me!
Seems like you are leaving out another peice of information.

1-When you open DB 1 you set c_do_what.varname to "Startup"
2-Then you go to DB 2 and set c_do_what.varname to "Relocate"
3-Then you go back to DB 1 where c_do_what.varname = "Relocate"
The question is, why didn't you set c_do_what.varname in DB 1 to "Relocate" in the first place?
Are you doing something in between?

But regardless, what you should do in DB 1 is:

if c_do_what.varname="" '[COLOR="Blue"]I don't see how this could happen 
unless as I said you are doing something in between.[/COLOR]
dim c_do_what as P
c_do_what = addin.variables()
c_do_what.varname = "Startup"
end if

Database 1 is a loader database that does some housekeeping functions when requested by database 2.

So when database 1 the first time, all it does is change to database 2 and the application runs.

Database 2 will have an option to re-locate the database (#2) to a new location. To accomplish this programmatically, it will be handled by database 1, but I need to send a message to database 1 to do that. That's why I'm changing the variable to "Relocate" and that's why I need to know in database 1 if the "c_do_what" variable has been previously declared and not to change it.

[martinwcole]

Re: Need a variable to persist from database to database?

Gabe, John is trying to deal with a scenario where when the app is on a users site, and they maybe change the folder name how to deal with it.

Correct, John?

I would have a table in the master adb that contained folder locations
if the user opts to change the folder location at startup, save the change, and then by default it would always know the location until changed again

[G Gabriel]

Re: Need a variable to persist from database to database?

John
By definition, addin variables will persist between databases,i.e. they will not go away unless you intentionally and explicitly delete them hence there is no need to use eval_valid() in this case.
The question is not whether it was declared. Once you dim this variable, it will be there, indefinitely, until you delete it. The question is what's its value? Is it "Startup"? Or "Relocate"? And what do you want it to be? and when and where?

[martinwcole]

Re: Need a variable to persist from database to database?

I'm not sure if using addins is the way to accomplish what you want. I use them to set the user name, rights, etc.

If I understand, all you want to do is have their choice point to the correct folder where the apps is installed - correct?

[jjfcpa]

Re: Need a variable to persist from database to database?

John
By definition, addin variables will persist between databases,i.e. they will not go away unless you intentionally and explicitly delete them hence there is no need to use eval_valid() in this case.
The question is not whether it was declared. Once you dim this variable, it will be there, indefinitely, until you delete it. The question is what's its value? Is it "Startup"? Or "Relocate"? And what do you want it to be? and when and where?

Garbriel

When the first database (the loader) gets loader, I have to use eval_valid() to see if the addin variable exists. And this works fine. Since it doesn't exist, it correctly dim's the variable and initializes the value to "Startup".

This is the initial code in the autoexec of the 1st database:

if not eval_valid("c_do_what.varname")

dim the variable
c_do_what = addin.variables()
c_do_what = "Startup"

end if

then a5.load the 2nd database.

When the second database gets loaded, if they select the option to "relocate the database" it does this.

c_do_what = addin.variables
c_do_what = "Relocate"
a5.load the 1st database

When it comes back to the 1st database, when it gets to the line

if not eval_valid("c_do_what.varname")

it always returns false and the c_do_what variable gets set back to Startup so the case statement just jumps back to the 1st database.

Does this make it any clearer?

[MikeC]

Re: Need a variable to persist from database to database?

John,
Just tell us what is supposed to happen--using the different scenarios that are possible--I just read the entire thread and don't really see a specific question / problem anymore!

As a side note---seeing as how even the addin variables do not exist when Alpha Five closes, if you want them to still persist then a simple text file read/write would get you there as far as retaining values.

[G Gabriel]

Re: Need a variable to persist from database to database?

John:
Again, you only need to dim the addin variable ONCE. I t will live in the stratosphere of your application until you kill it. Closing and re-opening the database does not kill it. So if you dimmed it yesterday or this morning, it will forever be there and that's why:
if not eval_valid("c_do_what.varname") will and forever be false that's until you intentionally delete this variable.

Sounds to me that you want:
1-c_do_what.varname to be set to "Startup" only and only when DB 1 is opened for the first time
2-Then c_do_what.varname will be set by the user in DB 2
3-Then when you go back to DB 1 c_do_what.varname stays at what the user set it in DB 2

So the real question is:
How to set c_do_what.varname to "Startup" when DB 1 is first opened then let the user set it afterwards?
Right?
If so, this should do it.

if eval_valid(c_do_what.varname)=.f.
dim c_do_what as P
c_do_what = addin.variables()
c_do_what.varname = "Startup"
end if

[jjfcpa]

Re: Need a variable to persist from database to database?

John:
Again, you only need to dim the addin variable ONCE. I t will live in the stratosphere of your application until you kill it. Closing and re-opening the database does not kill it. So if you dimmed it yesterday or this morning, it will forever be there and that's why:
if not eval_valid("c_do_what.varname") will and forever be false that's until you intentionally delete this variable.

Sounds to me that you want:
1-c_do_what.varname to be set to "Startup" only and only when DB 1 is opened for the first time
2-Then c_do_what.varname will be set by the user in DB 2
3-Then when you go back to DB 1 c_do_what.varname stays at what the user set it in DB 2

So the real question is:
How to set c_do_what.varname to "Startup" when DB 1 is first opened then let the user set it afterwards?
Right?
If so, this should do it.

if eval_valid(c_do_what.varname)=.f.
dim c_do_what as P
c_do_what = addin.variables()
c_do_what.varname = "Startup"
end if

Gabriel

You have 100% grasped the idea of what I'm trying to do; however, the problem is that your code (which is the same as my code) ALWAYS returns false - when DB 1 is loaded for the first time as well as when DB 1 is loaded from DB 2.

There in lies the whole problem. I can't NOT tell whether I'm running DB 1 for the first time (actually I can, because the eval_valid("c_do_what.varname") properly returns false), but when it returns from DB 2, it still returns false.

I would be happy to provide you with some code, DB's, etc. if that will help.

I believe you can also test this by just using the interactive mode in each database.