Any way to add a new line from a string with the '\n' character in flask?

Question

I was playing around with flask when I came across an odd problem with the '\n' character. it dosen't seem to have an effect in my browser, I tried putting
in there but it didn't work, any ideas?

from flask import Flask
from flask import render_template
test=Flask(__name__)
@test.route('/')
def root():
    str='yay\nsuper'
    return str
test.run(debug=True)

Answer 1

So it turns out that flask autoescapes html tags. So adding the <br> tag just renders them on screen instead of actually creating line breaks.

There are two workarounds to this:

1. Break up the text into an array

    text = text.split('\n')
   

   And then within the template, use a for loop:

    {% for para in text %}
        <p>{{para}}</p>
    {% endfor %}
   

2. Disable the autoescaping

   First we replace the \n with <br> using replace:

    text = text.replace('\n', '<br>')
   

   Then we disable the autoescaping by surrounding the block where we require this with

    {% autoescape false %}
        {{text}}
    {% endautoescape %}
   

   However, we are discouraged from doing this:

Whenever you do this, please be very cautious about the variables you are using in this block.

I think the first version avoids the vulnerabilities present in the second version, while still being quite easy to understand.

Answer 2

Newlines only have an effect on HTML rendering in specific cases. You would need to use an HTML tag representing a newline, such as <br/>.

def root():
    str='yay<br/>super'
    return str

Answer 3

In case someone end up here like me, and doesn't want to use {% autoescape false %}, for safety reasons, nor braking up the text which might be inconvenient in some cases, I found a good alternative here:

from flask import Markup
value = Markup('First line.<br>Second line.<br>')

and then in the jinja template:

{{ value }}

Answer 4

I come late to the party, but here's my solution.
HTML has a <pre> tag which can prove useful in this situation.

<pre>{{ your_text }}</pre>

This tag tells the browser not to automatically adjust spacing and line breaks.
To learn more about this tag check this guide out.

Answer 5

1. works for me and preserves security

I would suggest <br> rather than <p>

{% for para in text %}
    {{para}}<br>
{% endfor %}

then result is less bulky

Answer 6

Easiest way to do this

1. Create your template filter

@app.template_filter(name='linebreaksbr')
def linebreaksbr_filter(text):
    return text.replace('\n', '<br>')

2. Add this to your template

{{ someText|linebreaksbr }}

This will replace every "\n" character in your text with <br>.