Flask form validation technique

Question

This is currently the code that I'm using to validate and check for errors in a flask app, where the form fields are coming from a /registration html page:

@app.route("/register", methods=["GET", "POST"])
def register():
 if request.method == "POST":
 if request.form['register'] == 'Register':
 if request.form.get("eulacheck") != "on":
 return regError("Please read and agree to the Terms and Conditions and the License Terms.")
 if request.form['username'] == "":
 return regError("Please select a username.")
 if request.form['password1'] == "":
 return regError("Please enter a password.")
 if request.form['password2'] == "":
 return regError("Please confirm password.")
 if request.form['password1'] != request.form['password2']:
 return regError("Passwords did not match. Please enter passwords again.")
 username = request.form['username']
 password = request.form['password1']
 hash = bcrypt.hashpw(password.encode('UTF-8'), bcrypt.gensalt())
 id = randint(1000,9999)
 if request.form['email1'] != "":
 if request.form['email2'] == "":
 return regError("Please confirm email.")
 if request.form['email1'] != request.form['email2']:
 return regError("Email addresses did not match. Please enter emails again.")
 email = request.form['email1']
 insert_db("INSERT INTO Users (ID, Username, Email, Hash) VALUES (?, ?, ?, ?)", (id, username, email, hash))
 flash("Account registration successfull! Please use your credentials to login below.")
 return render_template("login.html",pageType=['login'],flashType="info")
 insert_db("INSERT INTO Users (ID, Username, Hash) VALUES (?, ?, ?)", (id, username, hash))
 flash("Account registration successfull! Please use your credentials to login below.")
 return render_template("login.html",pageType=['login'],flashType="info")
 return render_template("register.html",pageType=['register'])
def regError(message):
 flash(message)
 return render_template("register.html",pageType=['register'],flashType="danger")

This code seems a bit messy and repetitive, is there a better way that I should be doing this? Thanks a lot!

Answer 1

Looking at register(), the format is as following:

def register():
 if request.method == "POST":
 if request.form['register'] == 'Register':
 stuff()
 return render_template("register.html",pageType=['register'])

This can easily be condensed using and:

def register():
 if request.method == "POST" and request.form['register'] == 'Register':
 stuff()
 return render_template("register.html", pageType=['register'])

Also, you are not inserting whitespaces between arguments.

stuff(3,3) # <--Unconventional
stuff(3, 3) # <--More conventional

Another stylistic issue is some of your lines are too long. For all lines, line.length <= 79. You can read about the specific python conventions on the Python website.
For making it look less messy and repetitive, look at this answer to a Stack Overflow question. It is about implementing switch and case statements into Python, which seems perfect for your situation.

• cloudcrypt: Yup, I can definitely make the first and change, and I'll watch out for the whitespaces between arguments. Thanks a lot for the help!