[Python] Split a large Flask file using Blueprint

Introduction

When creating a web application using Flask, which is a web framework of python, the number of lines in the Flask file tends to increase, so I considered file division. It seems that file splitting using Brueprint is common in Flask, and this time I used Blueprint to split the file.

Directory structure

├── main.py
├── COMP_A
│   └── func_A.py
├── COMP_B
│   └── func_B.py
└── templates
    ├── COMP_A
    │   ├── index_A_1.html
    │   └── index_A_2.html
    └── COMP_B
        ├── index_B_1.html
        └── index_B_2.html

The main program is main.py. In addition, it is assumed that there are components A and B. Func_A.py and func_B.py in each component are files that use Flask respectively.

In flask, the html file is stored under the template, but this time, a directory for each component was prepared under the template and the html file was stored.

Source code

func_A.py

from flask import render_template
from flask import Blueprint

bpa = Blueprint('bpa', __name__, url_prefix='/A')

@bpa.route('/a1')
def app_a1():
    return render_template('COMP_A/index_A_1.html')
    #return "hello A a1"

@bpa.route('/a2')
def app_a2():
    return render_template('COMP_A/index_A_2.html')
    #return "hello A a2"

func_B.py

from flask import render_template
from flask import Blueprint

bpb = Blueprint('bpb', __name__, url_prefix='/B')

@bpb.route('/b1')
def app_b1():
    return render_template('COMP_B/index_B_1.html')
    #return "hello B b1"

@bpb.route('/b2')
def app_b2():
    return render_template('COMP_B/index_B_2.html')
    #return "hello B b2"

main.py

from flask import Flask

app = Flask(__name__)

from COMP_A.func_A import bpa
from COMP_B.func_B import bpb

@app.route('/')
def index():
    return 'Hello main'

app.register_blueprint(bpa)
app.register_blueprint(bpb)

if __name__ == '__main__':
    app.debug = True
    app.run(host='127.0.0.1',port=60000)

Originally, the function is registered for the app generated by Flask (name), but in the case of a function in another file, Brueprint is registered in the app using register_blueprint. At this time, don't forget to import another function Brueprint in advance.

call

Specify the following in the URL

127.0.0.1:60000/      #main.py   index()
127.0.0.1:60000/A/a１  #func_A.py  app_a1()
127.0.0.1:60000/A/a2  #func_A.py  app_a2()
127.0.0.1:60000/B/ｂ1  #func_B.py  app_b1()
127.0.0.1:60000/B/ｂ2  #func_B.py  app_b2()

Note that the URL is a combination of Prefix when Brueprint is specified and the path when @ xxx.route is defined.

Other

--File split using module There seems to be a way to split the file using flask.module. Consider next time.

• redirect It is necessary to specify the app name when performing redirect. For example, to redirect to b2, write as follows.

return redirect(url_for('bpb.b2'))