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Python

Posted by Dzumret Pelivani
Dzumret Pelivani
5,399 Points

Dont understand how should i replace part of email in for loop in jinja2/flask macro ?

In this challenge i need to create a macro for use in flask template to replace part of email string with '*'. But i can't figure out how should i do it inside a for loop.

Any tip are appreciated and reference to documentation where I can read about this and solve the challenge by myself.

lunch.py 
from flask import Flask, render_template

app = Flask(__name__)

@app.route('/')
def index():
    class User:
        email = None
    user = User()
    user.email = 'test@example.com'
    return render_template('user.html', user=user)
templates/macro.html 
{% macro hide_email(user) %}
{% for mail in user.email.split('@') %}

{% endmacro %}

2 Answers

Alx Ki
.a{fill-rule:evenodd;}techdegree seal-36
Alx Ki
Python Web Development Techdegree Graduate 14,810 Points

Hi, Dzumret Pelivani !

The way to replace is:

for letter in word:
    letter can become anything  ;)

Does it help?

Dzumret Pelivani
Dzumret Pelivani
5,399 Points

Thank you for your answer Alexey . I am familiar with loop through letters of a word.

But I don't understand how should i do it in a "macro.html".

In the challenge I have to solve the problem with for loop and a split. How do I transfer code bellow to Jinja2 syntax and macro ? Or is there any other simpler solution that I can not see.

# split the email in two
name, domain = 'test@example.com'.split('@')

# list to hold the new name with '*' 
new_name = list()

for index in range(0, len(name)):
    if index == 0:
        new_name += name[index]
    else:
        new_name += '*'

# join the new_name with rest of address parts and print out
email = ''.join(new_name) + '@' + domain
print(email)
Alx Ki
.a{fill-rule:evenodd;}techdegree seal-36
Alx Ki
Python Web Development Techdegree Graduate 14,810 Points

You can transfer it by using {%%} around keywords like for, and {{}} around variables or data what you want to see on page.

Example (using your code):

{% set name, domain = 'test@example.com'.split('@') %} # this is not visible on page
{{ name }} #   would print "test" on the page.

if you want to assign variables you have to use set keyword. But you don't have to assign them. Look:

{{user.email.split('@')[0]}}  # Would print name
{{"@"}} # Would print @
{{user.email.split('@')[1]}}  # Would print domain

Actually this will print full email address to the page!

What you need is: print first letter, print stars for each letter in name except [0], print @ and print domain.

example that prints first letter and stars:

{{user.email[0]}}
{%- for letter in user.email.split('@')[0][1:] -%}
{{'*'}}
{%- endfor -%}

So if email was "test@teamtreehouse.com" it would return t*** to the template.

Add @ and domain and wrap it all to

{% macro hide_email(user) %}
{# HERE #}
{% endmacro %}

PS The reason to use '-' in {%- for ... -%} is to remove whitespaces. jinja2 DOCS

Dzumret Pelivani
Dzumret Pelivani
5,399 Points
Dzumret Pelivani
Dzumret Pelivani
5,399 Points

Thanks a lot Alexey. Now i understand more of how Jinja2 syntax works.

And here is solution:

{% macro hide_email(user) %}

{{ user.email[0] }}

{%- for letter in user.email.split('@')[0][1:] -%}
    {{ '*' }}
{%- endfor -%}

{{ user.email[user.email.index('@'):]  }}

{% endmacro  %}

PS. Thanks for {%- -%} whitespace ignore

Alx Ki
.a{fill-rule:evenodd;}techdegree seal-36
Alx Ki
Python Web Development Techdegree Graduate 14,810 Points

Cool. This challenge took me a loong time too))

Thomas Helms
Thomas Helms
16,816 Points

My thanks to Alexey for {%- -%} as well. That was annoying to get over.