We’ll now break down each step in creating a minimal Flask app. The Python module that contains all the classes and functions needed for building a Flask app is called
We can begin building our app by importing the
Flask class, which is needed to create the main application object, from the
from flask import Flask
Now, we can create an instance of the
Flask class. Let’s save the application object in a variable called
app = Flask(__name__)
When creating a
Flask object, we need to pass in the name of the application. In this case, because we are working with a single module, we can use the special Python variable,
The value of
__name__ depends on how the Python script is executed. If we run a Python script directly, such as with
python app.py in the terminal, then
__name__ is equal to the string
'__main__'. On the other hand, if the script is being imported as a module into another Python script, then
__name__ would be equal to its filename.
As we’ll see in the next exercise, this distinction can be useful when we have code that we want to be run only if the script is executed a particular way.
Flask class from the
flask module at the top of app.py.
Create an instance of the
Flask class, passing in
__name__, and save the object to a variable called
At the bottom of the script, try printing
__name__. Then, run app.py.
What is the value of