Ejemplo de como crear una api con Flask que incluye conexión a Base de Datos

rest-api-flask-sample.py

#!/usr/bin/env python
import os
from flask import Flask, abort, request, jsonify, g, url_for
from flask.ext.sqlalchemy import SQLAlchemy
from sqlalchemy.inspection import inspect
from flask.ext.httpauth import HTTPBasicAuth
from passlib.apps import custom_app_context as pwd_context
from itsdangerous import (TimedJSONWebSignatureSerializer
                          as Serializer, BadSignature, SignatureExpired)

# initialization
app = Flask(__name__)
app.config['SECRET_KEY'] = 'the quick brown fox jumps over the lazy dog'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///db.sqlite'
app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True

# extensions
db = SQLAlchemy(app)
auth = HTTPBasicAuth()



class ToJson(object):
    def to_json(self):
        return {c: getattr(self, c) for c in inspect(self).attrs.keys()}

    @staticmethod
    def to_json_list(l):
        return [m.to_json() for m in l]


class User(db.Model, ToJson):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(32), index=True)
    password_hash = db.Column(db.String(64))

    def hash_password(self, password):
        self.password_hash = pwd_context.encrypt(password)

    def verify_password(self, password):
        return pwd_context.verify(password, self.password_hash)

    def generate_auth_token(self, expiration=30):
        s = Serializer(app.config['SECRET_KEY'], expires_in=expiration)
        return s.dumps({'id': self.id})

    def to_json(self):
        d = ToJson.to_json(self) #se genera el json
        del d['password_hash']  #se excluye del resultado el campo password_hash
        return d

    @staticmethod
    def verify_auth_token(token):
        s = Serializer(app.config['SECRET_KEY'])
        try:
            data = s.loads(token)
        except SignatureExpired:
            return None    # valid token, but expired
        except BadSignature:
            return None    # invalid token
        user = User.query.get(data['id'])
        return user


@auth.verify_password
def verify_password(username_or_token, password):
    # first try to authenticate by token
    user = User.verify_auth_token(username_or_token)
    if not user:
        # try to authenticate with username/password
        user = User.query.filter_by(username=username_or_token).first()
        if not user or not user.verify_password(password):
            return False
    g.user = user
    return True


@app.route('/api/users', methods=['POST'])
def new_user():
    username = request.json.get('username')
    password = request.json.get('password')
    print username
    if username is None or password is None:
        print "entre"
        abort(400)    # missing arguments
    if User.query.filter_by(username=username).first() is not None:
        print "aqui ando"
        print User.query.filter_by(username=username).first()
        abort(400)    # existing user
    user = User(username=username)
    user.hash_password(password)
    db.session.add(user)
    db.session.commit()
    return (jsonify({'username': user.username}), 201,
            {'Location': url_for('get_user', id=user.id, _external=True)})


@app.route('/api/users/<int:id>')
def get_user(id):
    user = User.query.get(id)
    if not user:
        abort(400)
    return jsonify(user.to_json())

@app.route('/api/users/list')
def get_users():
    users = User.query.all()
    return jsonify({'users':User.to_json_list(users)})

@app.route('/api/token')
@auth.login_required
def get_auth_token():
    token = g.user.generate_auth_token(600)
    return jsonify({'token': token.decode('ascii'), 'duration': 600})


@app.route('/api/resource')
@auth.login_required
def get_resource():
     return jsonify({'data': 'Hello, %s!' % g.user.username})

if __name__ == "__main__":
    if not os.path.exists('db.sqlite'):
        db.create_all()
    # app.run(debug = True)
    # app.run(host=os.getenv('host','0.0.0.0'), port=int(os.getenv('port',8080)))
    app.debug = True
    app.run(port=int(os.getenv('port',8080)))