Python-powered Chat Apps with Twilio and SendGrid Transcripts
Chapter: Creating the Flask Python web app
Lecture: Create the Flask app

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0:00 It's time to finally start writing some Python code. We've been coding over in Twilio studio, and now it's time to write our Python code.
0:09 And this is really, really exciting going to be one of the funnest parts of this course for sure. It's a good chance to remind you about the GitHub,
0:15 repository over in chapter three. I've exported the JSON definition of what we've done so far for the workflow over there and sort that JSON file here.
0:27 Be sure to go and get the GitHub repository fall along now in this particular chapter Chapter 4, I'm going to walk you through.
0:38 Setting up the project in PyCharm is really, really close to what you would do in Visual Studio Code as well and get everything
0:45 ready to go. And then afterwards, Chapter 5,6 and 7, I'm just going to say I opened it the same way Okay, so this is the one time well,
0:53 sort of really step by step. I go through it, for our project. We're going to need to use Flask no surprise for our flask app.
1:02 And whenever we have external dependencies like that, it's a really good idea to have a virtual environment.
1:07 This is an isolated environment that you can install stuff, too, and only the things for this application and it's dedicated versions will be installed
1:14 Gonna go over here, have a little cool app called Go to Shell that will open up the working folder there.
1:23 And what I want to do is I want to create a virtual environments will say Python3 -m venv, That's the commander of the module,
1:30 and then venv is going to be the folder name. Now with this folder, we have to activate it. So we'll say .venv/bin/activate, now on macOS and Linux.
1:42 This is what you do on Windows. You would just say venv/scripts/activates or activate.bat.
1:49 Why those are different? I have no idea you're in the windows. Just be aware. You got to do that as well.
1:53 And you may also have to type potentially could type Python3 Python. Just make sure you're using the right version of Python there,
2:00 and then we need to have a file where we define our dependencies. Don't need to create a file. Just use touch or we could use in our editor.
2:07 I'll just go and do it here for the first time and then do the rest in the editor requirements.txt We're also going to have a file called
2:17 So Windows you can just open this up in pycharm and create those two files I don't think touches in Windows these days, anyway. So now over here,
2:27 we've got our application file. We've got our requirements and a virtual environment. Let's go ahead and open this in pycharm on macOS.
2:34 You can drag and drop this onto the dock icon and will open on Windows and Linux. You have to simply say file open directory and browse to it.
2:44 You see, it's a founder virtual environment. It's colored it and then ignored way. So that's good. And it's got are two files here.
2:52 It also automatically discovered our virtual environment, this one that we had created. If it doesn't do that, you can just go over here.
2:58 Sometimes it doesn't say add interpreter and browse to it, but let's go and set our requirements first. We'll say flask and says, Oh,
3:07 look, you're going to need to install flask. So in pycharm, I can just click this button and frequently I will.
3:13 But this one time we'll go down to the terminal notice the virtual environment should be active and we'll say pip install -r requirements.txt
3:20 How about we try it with two l's There we go Now, We always want to recreate a virtual environment. It's almost always out of date.
3:32 The pip command is out of date, which is unfortunate, but we just run that little thing to make sure we don't get warnings again. Right now.
3:40 We should be good to go. Take a moment for PyCharm to realize that was installed. And now it is. If you worked with flask before,
3:47 it's really easy to create a minimal flask app. So we'll just say import flask. The way it works is we create this thing called an app,
3:54 and we'll say flask.flask(__name__), pass in the name of the file Here, we're going to define a function.
4:00 I'll call it Index that's just going to listen to / and it will return Hello world. Now, this is not enough to make it an in point that
4:10 Flask will host or the Web browsers can talk to. We have to tell flask, Hey, this is part of somewhere URL's we say app.route ('/').
4:18 That means just you go to the server or domain name. That's what we want. All this is great, but it's not enough to actually run the program.
4:26 So we're going to use the Dunder named dunder Main convention, which is only do this command if you're actually trying to run the file,
4:33 not trying to just import it and pycharm happens to know that this is very common. So every type main tab it will write the code to say,
4:41 Am I being run directly or am I just being used in other ways? So if that's the case, we'll say Run and of it goes.
4:47 Final comment here. Notice at the bottom. There's like these little comments. If I format, the code will do one thing by going cut a line out.
4:57 It'll show you what command that was and so on. So you'll see me using hot key's and not just the menus throughout this course,
5:04 and those over here will show you what the command is that I used what the hot key was if it was a hot key, or even if you click a menu item.
5:13 If I click this even though I click the menu item, I still get to see the hot key pop up there. So if you're wondering what's going on,
5:22 be sure to keep an eye on the little green section down there at the bottom Last thing to do is to run it,
5:27 see if it works. Now there's a cool button right here that looks like she's going to click it and run it and even shows me if I had control+r
5:32 it'll run it. But there's nothing set to run, so we're gonna choose that we're gonna run this app. Then it runs down the bottom.
5:39 It looks like it's up and going, and subsequently I'll have the controls to run this app. Click on it and Hello world not super impressive,
5:48 but it is kind of impressive, how simple this app is that we've got here.
5:53 Get everything set up. So just 13 lines of code with all the proper spacing in there and we have our hello world flask app, up and running.

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