access data from pymongo

一、connect database

from flask import Flask, render_template, flash, request, url_for, redirect
from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, SubmitField
from wtforms.validators import DataRequired, EqualTo
from pymongo import MongoClient
# mongodb
from pymongo import MongoClient

myclient = MongoClient("mongodb://127.0.0.1:27017")
mydb = myclient["supermarket"]
mycol = mydb["members"]
myusers = mydb["users"]
print("Connection Successful")

二、login function, use for ... in to access data from database

# create form class
class Login2(FlaskForm):
    username = StringField('username', validators=[DataRequired()])
    password = PasswordField('password', validators=[DataRequired()])
    submit = SubmitField('Submit')

@app.route('/login', methods=['GET', 'POST'])
def login():
    login_form = Login2()
    if request.method == 'POST':
        vals = request.form
        username = vals.get('username')
        password = vals.get('password')
        #get all users list
        showUsers = []
        if login_form.validate_on_submit():
            #getUsers is a cursor instance
            getUsers = myusers.find({"username":username})
            getAllUsers = myusers.find()
            
            #.conut(), you can know whether there is a user
            returnCount = getUsers.count()
            if returnCount != 0:
                for val in getUsers:
                     #use for ... in ... to access data from cursor object
                    for users in getAllUsers:
                        # put all users obj in the showUsers list
                        showUsers.append(users)
                return render_template('index.html', username=val['username'], users = showUsers)
            else:
                return render_template('register.html',form=login_form, status = "No User")
    else:
        return render_template('register.html', flag = 'login', form=login_form)