Back-end Python for Front-end [closed]

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Back-end Python for Front-end [closed]

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I made a simple application that registers a data in a sqlite3 database, all this part of the Back-end is done in Python with .py files running in the same terminal, so my use already serves me excellently. Now I want to visualize the data in a web page even to study HTML CCS and JS. Can you query the Sqlite3 data in JavaScript? to fill in the data on the web page, even if you have a .py file serving this data, what is the best way to do this?

python

asked by anonymous 08.11.2018 / 19:50

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How to send a query to an arrayadapter? Save html form input in csv

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Can you query the Sqlite3 data in JavaScript?

Actually yes .... sqlite has been compiled for javascript and is called sql.js . Can be downloaded here link

Small use example:

var sql = window.SQL
var db = new sql.Database(banco);
var res = db.exec("SELECT * FROM hello");
console.log(res);

Here is a more complete example link

Even if you have a .py file serving this data, what is the best way to do this?

Although it is possible as I showed above, it is quite unusual to use javascript to read sqlite. The most common is to create a client / server application - the client is the browser and accesses a network address, where the server, written in python, is running and serving requests. To use this method you must choose a web framework , that is, a library of functions to facilitate the creation of a web service. There are many: django , sanic , flask , cherrypy ... Each one with its advantages and disadvantages, some more complete, others more flexible ...

To end I leave a super simple example using flask and sqlalchemy ; The purpose of the example is to show something working, so you can save it in a teste_web.py script and run it, it will work directly.

from sqlalchemy import create_engine, Column, String, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from flask import Flask, request

e = create_engine('sqlite:///arquivo.db', echo=True)
Session = sessionmaker(bind=e)
Base = declarative_base(bind=e)
class Usuario(Base):
    __tablename__ = 'usuarios'
    id = Column(Integer, primary_key=True)
    nome = Column(String(200))
Base.metadata.create_all()

app = Flask(__name__)
@app.route("/", methods=["GET", "POST"])
def indice():
    s = Session()
    result = '<html>' # monta variavel com html a retornar
    if request.method == "POST":
        usuario = Usuario(nome=request.form["nome"])
        s.add(usuario)
        s.commit()
        result += '<p>Usuario incluido com sucesso!</p>'
    result += '<table><tr><th>ID</td><th>Nome</th></tr>' #cabecalho
    for usuario in s.query(Usuario):
        result += '<tr><td>{0.id}</td><td>{0.nome}</td></tr>'.format(usuario)
    result += '</table><form method="POST">Incluir novo usuario:'
    result += '<input name="nome" /><input type="submit"></form><html>'
    return result

if __name__ == '__main__':
    app.run()

This simplified example will create the database in sqlite with a table named usuarios and then waiting for its access at address http://localhost:5000 . When you access this address with your browser, you can view the contents of the table and include new users:

Remember that this is just a simple example - When developing your application, you need to take more into account; One of the points to change is that we are creating HTML manually, the correct one would be to use a template language to facilitate the generation of html (like jinja2 );

I hope I have helped and given you a push in the right direction.