title: Flask & Alchemy - (psycopg2.OperationalError) FATAL: password authentication failed
body: <p>I'm new to python. I have to develop a simple Flask app (in my local Ubuntu 16.4)  with PostgreSQL as database.</p>
  
  <p>I install pgadmin, Flask, SQLAlchemy and postgres and also this is my app code:</p>
  
  <pre><code>from flask import Flask
  from flask_sqlalchemy import SQLAlchemy
  
  app = Flask(__name__)
  app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://dbUserName:userNamePassword@localhost/dbName'
  
  db = SQLAlchemy(app)
  class User(db.Model):
      id = db.Column(db.Integer, primary_key=True)
      username = db.Column(db.String(80), unique=True)
      email = db.Column(db.String(120), unique=True)
  
      def __init__(self, username, email):
          self.username = username
          self.email = email
  
      def __repr__(self):
          return '&lt;User %r&gt;' % self.username
  
  @app.route('/')
  
  def index():
      return "Hello Flask"
  
  
  if __name__ == "__main__":
      app.run()
  </code></pre>
  
  <p>Also I create a database and new user in pgAdmin (and replace them with related variable in my code), but when I try to test this code in python shell I found error.</p>
  
  <p>my python code:</p>
  
  <pre><code>from app import db
  </code></pre>
  
  <p>result:</p>
  
  <pre><code>/home/user/point2map2/venv/lib/python3.5/site-packages/flask_sqlalchemy/__init__.py:839: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future.  Set it to True or False to suppress this warning.
    'SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and '
  </code></pre>
  
  <p>Then:</p>
  
  <pre><code>db.create_all() 
  </code></pre>
  
  <p>result:</p>
  
  <pre><code>(psycopg2.OperationalError) FATAL:  password authentication failed for user "dbUserName"
  FATAL:  password authentication failed for user "dbUserName"
  </code></pre>
  
  <p>after a lot of search in forum I found this guide:</p>
  
  <blockquote>
    <p>in your pg_hba.conf</p>
  
  <pre><code># IPv4 local connections:
  # TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD
  host    all         all         127.0.0.1/32         trust
  </code></pre>
  </blockquote>
  
  <p>But its not work for me.</p>