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Now in the last lesson,

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we managed to get our password manager to start saving the data that we're

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entering inside the password manager.

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And we formatted it and put it inside our data.txt.

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Now,

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one of the things that was a bit of an issue in terms of user experience is

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whenever the user actually enters their details into this password manager at the

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moment,

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it doesn't actually give you some sort of way of knowing that it was successful

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or if it was not,

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or actually getting them to check and verify that the data that they've entered

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is definitely the one that they want to save into the file.

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In order to do this,

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we're going to learn about something else that you can do with tkinter

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which is something called standard dialogs.

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These are basically popups that your tkinter program can generate.

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And one of the most popular standard dialogs are the message boxes.

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And it's really, really easy to create these popups.

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You can simply just import the message box module

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and you can tap into methods like show info or show warning, show error,

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or you can ask the user yes no, or OK

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or cancel, ask a question yes or no,

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ask to retry or cancel.

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Now the screenshots where made in a Swedish version of Windows,

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but we can actually try these out ourselves and start putting in some standard

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dialogs so that we can give the user some feedback.

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The thing that we really want to tell the user is the moment that the save

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function is called it's because they pressed on the add button here.

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But before we actually commit all of the current information to the file,

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we want to check and make sure that they're actually happy with what they've

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written.

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So we can create a message box here and get them to check the details that

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they've entered and then hit yes or no as to whether

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if they want to save it. In order to use the message box,

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we actually have to import the message box. Again,

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it's from the tkinter module that we're going to import the message box module.

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Now notice how this is not actually a class. So that's why,

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even though we've said * which means import everything,

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it actually only imports all of the classes, the constants,

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but it doesn't import things like the message box,

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which is simply just another module of code. And in fact,

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if you right-click on it and go to implementation here,

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then you can actually see this messagebox.py file and how it's implemented.

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The thing that's important though is to actually put it into use. So we can use the

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message box and call a method to show a popup.

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The simplest type is just showinfo

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which you only need to think about two things

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really; a title and also a message.

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So I'm just going to put title as title and message as message.

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And you can see when I press add,

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I get this up and it's just got the title and the message and you can't do

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anything other than click OK.

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In addition to showinfo,

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there is actually a lot of other methods; you can ask yes or no,

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ask retry or cancel. You can show an error or you can show a warning.

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Now in addition, you can actually ask the user something.

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So this generates two buttons, yes or no, retry or cancel,

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OK or cancel, ask question is also yes and no, and we've also got yes,

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no and cancel here. What I'm going to do is I'm going to ask OK

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or cancel.

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And what I want to ask the user is I'm going to set the title as the website

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that they've entered

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so that's going to come from here, and then I'm going to set the message as a

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f-string.

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So I'm going to say these are the details entered:\n.

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And then I'll give them the email that they entered

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and then a new line and the password that they entered.

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And then after new line, I'm going to ask them, is it okay to 

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save?

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If I go ahead and run this code,

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you can see that when I type a website

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say Amaazon

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and I type in my password and I click add,

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I get my popup and it says these are the details entered. This is email,

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this is the password, is it okay to save?

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Now what I want to do is when they click OK

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then for that action to go through and for us to write to our data file.

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But if they click cancel,

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I want them to be able to go back to the screen and edit it if necessary.

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In order to do that,

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we have to receive the output from this method call,

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which is going to be a boolean. It's going to be either true or false.

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So I'm going to set that to is_ok.

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Now if this is_ok  is true, well, in that case,

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we're going to go ahead and do all of this. So write

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to file and delete everything that's inside the entry.

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But if it's not okay, then we're simply just going to do nothing

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and the popup box will dismiss itself. Now,

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if I run this code again and I type in some ### and I click add,

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you can see if I click cancel, nothing happens, and I go back. But if I click

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OK,

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then all of that information is going to be to my data.txt like here.

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Now it's time for you to have a go with the message boxes and these standard

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dialogs.

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But your job is to figure out how can we get our app to have a little bit of

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validation because when they have an empty website and an empty password and

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they click add,

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you shouldn't really let them save an empty password and an empty website,

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right? That's not right.

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So we want to check to see if the length of the entries in the website or the

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password is zero. And in that case,

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we're going to bring up a message box

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that's just going to tell them basically that, Hey,

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you've left some fields empty. So this is what you're aiming for.

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Let's say that you've left the website or the password empty and you click add,

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you should get a popup that tells you, Hey, don't leave any of the fields empty.

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And this should trigger when either the website or the password is empty.

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So have a think about how you might solve that challenge and give it a go.

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Okay.

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All right. So here's where we get all of the information from our entries.

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And this is also a good time to do this validation.

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We can use an if statement to check, well,

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if this website string has a length of zero,

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then that means the user didn't type anything in there.

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And we can use an or statement to check well,

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if the password also has a length of 0, well,

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in that case, they didn't type anything in there either.

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Now you can also add validation for the email,

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but because we have the email already pre-populated,

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there's actually not much point here.

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So if either they've left the website blank or the password blank,

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then we're going to generate a message box and we're going to use the showinfo

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message box. The title is just going to say

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Oops, and the message is going to say

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Please make sure you haven't left any fields empty.

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And now when you run this code, if you've left either of these two empty,

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then you are going to get a popup that tells you this.

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Now we don't actually want the rest of this code to happen if this is true.

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So let's go ahead and add an else statement as well so that we can indent all of

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this so that we only continue forward

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if in fact, the length of the website or the password is not equal to zero.

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So in this case, when they leave it empty, you can say OK

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and it just goes back to let you continue entering more details.

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Now in the next lesson,

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we're going to add another piece of functionality to our application

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which is the generate password.

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We've already seen how terrible the passwords are that we come up with from our

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own heads.

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So we're going to be using the generate password code that we created many,

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many moons ago as one of our projects

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and we're going to be embedding that into this application.

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So for all of that and more, I'll see you on the next lesson.