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Coding Session: Enhancing PowerShell Scripts with Parameters and Error Handling
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Apr 3, 2024
This coding session goes through adding PowerShell parameters and error handling to make your script more better-er! foreach and CSV File Tutorial: https://youtu.be/fMrRosJYuXs?si=Vp237hVDz6chRvMH Master PowerShell Errors with Try Catch Blocks https://youtu.be/KVwMajS1sSc?si=3w8liRvDWvJpdABs 00:00 Introduction 00:28 Connection Check 03:00 File Input Parameter 06:46 Error Handling 11:48 Summary
View Video Transcript
0:00
What's up, everyone
0:00
Today, I want to go over PowerShell script that I featured in a previous video
0:04
when I talked about 4-Reach and CSV files and see how we can make some improvements to it
0:09
to make it more PowerShell-y, if that's a word. What we'll do is go through and make three changes to it
0:16
including parameters, some error catching, and then modifying how we're making sure we're connected out
0:22
to Microsoft Graph in order to create our users out in Active Directory
0:27
Let's go ahead and get started. First, in the script on lines one and three
0:32
and then down here at the very end is where I'm managing a connection out to Microsoft Graph
0:36
which is the PowerShell module I'm using to create users out in Enter ID
0:42
Instead of force creating the connection like this and then disconnecting at the end
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I'm going to change this just to where it checks to see if a connection exists
0:51
and if it doesn't, just exit the script or something like that and prompt the user
0:56
to create a connection before they run the script. So first, let's go ahead and get rid
1:01
of these first couple of lines, and we'll go ahead and get rid of disconnect graph here
1:07
And then at the very top, let's create a variable called connection
1:13
And there is a command called get-mg-context. This is going to show your current connection
1:18
out to Microsoft Graph. It'll show you what scopes, what user account
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you're connected to and everything like that. In fact, let's just go ahead and run this down here
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in my PowerShell window, and you can see nothing comes back. What I like to do is if there's a command like this
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to see if you have a current connection to something, maybe it's Microsoft Teams or Exchange Online, SharePoint
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I'll save the output of that command to a variable. And then we can just check to see
1:45
if that variable has a value. So in this case, I'm going to say null equals connection
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basically meaning does the connection have any value into it, and if that is true
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that means we don't have a connection. Let's do a write warning message
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and let's say you must run connect-mg-graph before running this script
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And then we will do, let's do an exit. This should be a very minor change of just saying
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if you're not connected out to Microsoft Graph, you don't have that connection details
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we are going to exit the script. Okay, let's go ahead and give this a try real quick
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We'll say new entry user, and there it goes. Perfect, you must run connect-mg-graph
2:36
before running the script. Let's go ahead and do that, and then offscreen, I'm authenticating here
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We'll finish that up. We come back, welcome to Microsoft Graph, and just to show you, let's go back and run get-mg-context
2:51
and you can see all my context here, the account I'm connected with, what scopes I'm connected under, and so on
2:58
So, perfect. The next part of the script we want to improve is line eight here
3:03
We're importing the user data that we want to run through in the form of a CSV file
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I still have that example CSV file over here on the right, just has first name, last name, department
3:14
and some information in it. What we have right now is the path to the CSV file
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is hard-coded, so if you ever wanted to use a different file, you'd have to come in here
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and modify the script to point to that, and that's not very PowerShell-like
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What we want to do is have a parameter where we can pass in different files
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and not have this hard-coded. In order to pass in the file that we want to use
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in the script, we need to define a parameter that includes the, it could just be the file name
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or the full path, depending on the location where you're running the script from
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And to get started, we need to define a parameter, so we're going to use the param keyword
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and some open and close parentheses. Then we need to give our parameter a name
4:00
I usually like to do, let's say, user data file. Now, at this point, this parameter is valid
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We should be able to use it. We would run new entry user dash user data file
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and give the path to the file name. We do want to be a little more specific
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in our parameters here and define what type of data we're expecting to come into this
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Is it going to be a number, an object, a string, or anything like that
4:28
In this case, it's going to be a string. Some people will put the data type definition
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right in front of the variable name here or the parameter name here
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I like to just put it on a separate line like this. That's just my preference
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This or this are both valid. I think I like seeing the parameter name there
4:50
on the far left, just so I can visually see it a little bit better for me
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In its current state, user data file is not mandatory or we don't need it to run the script
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But in our case, it is the most important part of the script that we have here
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So we want to make sure that when people run this, that they use this parameter and provide a value
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What we can do is then add a parameter definition here, a parameter attribute
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Now, at a minimum, you could just leave it like this. It just says parameter. We don't have any other attributes in it right now
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But we want to make sure this is a required parameter. So as you can see, you start typing
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and we now make it mandatory. So now, if I were to try to run this again
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it is going to prompt and say you need to provide the path to the user data file and it won't let me run it
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So let me Control-C out of here and clear the screen. Now that we've got our parameter
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we need to actually use it. So here, we're going to replace our path
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and we will just say user data file. There are some additional checks we could do
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within the parameter definition itself. We could have a validate script that will test the path
6:05
of the user data file that we pass into it and make sure it exists
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Or we could do something similar down here. We could try to do the import
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In fact, what does that look like real quick? If we do csv path C does not exist
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some file.csv, that does error out like that. There is some built-in error catching there maybe
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If it tries to import and it doesn't exist, hopefully it's bad enough for a terminating error
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that the script would then exit out. Right now I'm fine with this
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If it doesn't keep going, then the foreach is not going to iterate through any data
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So we're good to go there. All right, so far we have our parameter definition
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We changed up how we're making sure we're connected out to Microsoft Graph. Before we continue, we've got our foreach
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Everything is good there. The last thing I want to take a look at is our command here on line 37
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to actually go and create the user. Generally creating users should be pretty straightforward
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Hopefully you don't run into any issues. When I was recording the last video
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where I first featured this script, I did run into an error because all the users
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I was trying to create already existed and the errors it threw out weren't very intuitive
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for anything like that. What I want to do here is just add a try catch block
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on line 37 to make running into errors just a little more visually good in our script here
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I do have another video on the channel going over try catch blocks
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I'll include a link to it down in the description. Let's put in our basic try catch block
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and we'll start building this out. And then I'm going to add error action stop
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Just in case this is not a terminating error, I do want it to stop and go into my catch block
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Let's create a variable here. I'm going to call it error message
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I'm going to use get error newest one. So this I'm just saving the error message out to a variable
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and then we'll do write warning message. And let's just do error message right now
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Let me go ahead and save that. Okay, so basic try catch block
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We're just going to output a warning message here of what the exception was
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Clean up our spacing a little bit. Now, for looking over at our CSV file
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we see the Jeff Brown account is the first account it's going to try and create
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I do know that account already exists and I want to test my error catching here a little bit
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So let's add just the first index in our imported data here in our array
8:53
Adding the index like this will just limit to the first item in our user data variable
8:58
which is all the data inside our CSV file. So I know this is going to error out
9:05
Let's do new entry user. User data file example. Let's see CSV
9:13
So this should error out. Perfect. So this is the message that I got the other day
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but it says another object with the same value for property user principal name already exist
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That's a really fancy way of saying this user already exists. What I wanted to do in this case is just try
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and clean this message up a little bit and give me a custom message
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that maybe makes a little more sense within the script. So I'm going to highlight our message here
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And inside the catch, you can do any number of things that you want to
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in order to handle the error. So what I'm going to do is say if error message
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we'll say I like, put some wild cards around it. Here, all I'm doing is if the error message
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is like this string phrase here, another object with the same value
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I'm going to change my warning message here. What I'm going to do is output that
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this specific user already exist. Fix up my quotes here. Already exist
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Now, if our error message isn't like that, we'll just output the warning message here as usual
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Okay, so just go back through, try it. We're going to get our latest error message
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If the error message is like this phrase here, we're just going to output a different message
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We'll put in the name. We'll just say it already exists. We'll just say it already exists
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else write out whatever warning message we have. So let's go ahead and try to run this again
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So it's a little more useful. Normally, if this ran through, we wouldn't know what user existed
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but now we know Jeff.Brown at this address already exist. But for the rest of our users
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it should be able to go through and create them just fine. This is also helpful if you're outputting to a log file
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if you're creating a whole bunch of users, or if you need to log what users it's creating and everything
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Okay, so with our updated script file here, let me get rid of our zero index
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I want it to run through the rest of my users here as it runs
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Pull this up here. Perfect, yeah. Did those last three really quick
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and we saw Jeff.Brown already exist, but the rest of our users were created successfully
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That does it for this video. Let's go back through real quick what we did. First, we added a parameter
11:53
so we could import different CSV files that we needed for our user data
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It wasn't hard-coded. We changed how we checked for connections. We weren't forcing to connect out and then disconnecting
12:05
because maybe you're already connected to Microsoft Graph in your current PowerShell session
12:09
And then we added just a little bit of error handling here
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We put it in a try-catch block. I had a specific error
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that I wanted to handle a little bit differently and just output that this user already exists
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Otherwise, we just output the error message and go on from there
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The error catching here can evolve as you run through and try the script more often
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You can continue to modify the catch block here or find a specific exception type
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that you maybe want to handle, but otherwise I think the script is in a lot better shape
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One other improvement might be not passing any file with the user information
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but maybe you want to run new entry user and then provide the first name, last name department
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That would definitely be another way to make the script more dynamic
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and maybe we could save that for another video. Otherwise, I think coming up next
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we'll take a deeper dive into parameters and maybe take a look at hash tables as well
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So stick around for that. Thank you for watching and we'll see you next time
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