Storing the username of the Windows user

[Seth Schrock]

My plan is to use the username of the user that is logged into Windows to filter the data in my forms (record access control). I need to know the best way to store the username.

My understanding of public variables that aren't inside any sub or function is that any value assigned to them is retained until the database closes. My thinking is that I could obtain the current username and assign it to some variable when the database first opens and then use this variable as my filter for any form that needs filtered.

The other option that I see is to have a local table (not in the BE) that could store the username and then empty it when the database closed so that there would only ever be one username in it. The username could then be obtained from the table whenever needed.

Not sure if this would decrease performance, but I could also just pull the username each time I needed it and not store it at all (I'm planning on using the Environ("Username") function to get the username).

I'm sure that I could get any of these methods to work, but getting it to work doesn't mean that it is the best way.

[zmbd]

Seth,
A few ways to do this and in v2010 you now have the temp variables to store information. I have used a table as you've suggested, forms, class modules, and global variables (what you're calling a public variable). Each has their advantage and disadvantages... one such is that a global variable can loose its value in some cases.

As for obtaining the user name, the environment variable can be spoofed if a user knows how... there is an api call (you should be able to find it with a search here... I'm not at work where I can pull that code today) that is a tad more secure.

[Seth Schrock]

I found the api to get the user name. I have no worries about my users having the knowledge to change the user name, but I like to get into the habit of coding my databases to the best solution, not just one that works.

Now that you mention that global variables can loose their value, I think that I have heard that before. So, it seems that I'm down to either calling for the username each time I need it or storing it in a table. My guess would be that it would require less resources and allow for faster load times of my forms if I store it in a table. I would then use DLookup() to get it when needed instead of running the api all over again. Would this be correct?

[NeoPa]

A link to what Z is referring to (Function to Return UserName (NT Login) of Current User). He makes a good point ;-)

As for how best to store the value when retrieved, I believe Temp Vars in A2010 is the best way if available. Otherwise, a table could be used but you'd need to ensure the value is reset whenever the project starts to avoid spoofing. A way I often use (as I still work mainly in A2003) is to store it in a form that stays open throughout the project. Visible or otherwise is irrelevant. I then also have a Global variable which I check for contents before accessing. If the variable contains a ZLS (Zero Length String) I make sure it is reloaded from the form.

This extra level of checking is because a project can be reset in many ways while in use and that would reset all variables, but not the data on forms or in your tables.

PS. We cross-posted Seth, but I believe I have answered all your questions anyway :-)

[Seth Schrock]

As I am using A2010, tempvars are available so I will try to learn how to use them. I think I have found a website that tells me all I need to know, but if I end up having trouble, I will post back in another thread.

Thanks Z and NeoPa for your help. It is very much appreciated.

[NeoPa]

Always a pleasure Seth :-)

I believe TempVars were introduced in A2010 specifically in order to handle the problem where data stored in variables are all reset when any unhandled bug occurs in the project. Depending on the setting of when to break in the VBE options, this will prompt with buttons either to End or Debug. End causes the project to be reset. If no break occurs then this happens anyway.

[zmbd]

I knew I should have checked the insights!
Yes the link Neopa provided mirrors what I use.

As for my prefered (as earlier versions didn't have the temp var collection) I like the "form" method. Makes it nice during alpha and beta testing as I can leave the form visible and verify that certain things are set as expected. Also, I include a timer function that checks for activity and a flag to soft or hard logoff users... not nearly as indepth as others have posted here for such - but it works.