I am loading data from a database. The textual data has line breaks \n as uploaded by the user, I would like to print this data on a html page. However line breaks do not occur. I have tried replacing \n with <br>, but that prints with <br> as part of the string instead of actually breaking the line.
How I replace
value['description'].replace('\n', '<br>')
How it appears:
I have realized mine is a framework specific issue as guided by #Demian Wolf's comment, my html markup was getting escaped. Since I am using django framework, adding a safe call in was the solution.
{{ value.description | safe }}
You can use the linebreaksbr templatetag
{{ value|linebreaksbr }}
or in your view
from django.template.defaultfilters import linebreaksbr
linebreaksbr(value['description'])
I am passing a python list to a django template like this:
in views.py:
dat = [-77.448599999999999, 37.536900000000003, u'Virginia War Memorial', 1.0]
result={"dat":dat}
return render(request,'result_map.html', {'form': form,'result':result})
and in my template:
var dat = {{ result.dat }}
but in the rendered html I get:
var dat = [-77.448599999999999, 37.536900000000003, u'Virginia War Memorial', 1.0]
which gives an error.
How can I get:
var dat = [-77.448599999999999, 37.536900000000003, 'Virginia War Memorial', 1.0]
thanks
I think you need to pass it through the safe filter if you want the raw string:
{{ result.dat|safe }}
You can also use the {% autoescape off %} block if you want to affect a larger block of the template.
var dat = {{ result.dat }}
You're trying to inject into JavaScript, presumably in a <script> block. You need output that is formatted in JavaScript syntax, but you're implicitly converting a Python list to a string, which will give a Python-syntax list literal, not a JavaScript one. There are a number of differences, including text (Unicode) strings in the list being prefixed with u in Python 2 but not JS.
You're also using the default autoescaping for Django templates, which is HTML-escaping. That would be right for injecting into HTML content, but you're injecting into JavaScript, so you get wrong escapes like ' for '. You can prevent this by adding the |safe filter to avoid the HTML-escaping, but then you have no escaping at all, so your page will be vulnerable to script injection (cross-site scripting).
The right way to output a structured value into a <script> block is:
json.dumps to turn it into a JSON string
replace any instances of the character < in the string with the JSON string literal escape \u003C, so that the string </script> can't be used to escape from the <script> block and inject HTML
mark as safe.
You can combine these operations into a custom filter. Unfortunately Django itself doesn't ship one.
A better approach is to avoid injecting into JavaScript at all. Instead write the json.dumps output into the HTML document using the standard escaping and read it from there using DOM:
return render(request, 'result_map.html', {'form': form, 'dat': json.dumps(dat)})
...
<body data-dat="{{ dat }}">
...
var dat= JSON.parse(document.body.getAttribute('data-dat'));
this allows you to keep your JS completely out of your HTML pages, which would also allow you to use more secure Content-Security-Policy settings.
i have a text area tha is tinymce application that devolve the text introduce in html.
so if i introduce this:
I, this is an example.
that i recive,<p> I, this is an example.</p>
in my view i remove the html tags, and if the tag are "p" than replace for an\n.
result:I, this is an example.\n
but if i introduce this:
I,
this is an example.
this return:
<p> I,</p>
<p>this is an example.</p>
result:
I,\n
this is an example.\n
I want to remove the line break, so the result are:I,\n this is an example.\n
I would recommend fixing the <p> tag issue on the client side, as you can configure tinymce not to use <p> tags at all:
tinyMCE.init({
...
forced_root_block : false
});
http://www.tinymce.com/wiki.php/Configuration:forced_root_block
this is my code :
string ='''
{% emoji 'MONEY_BAG' %}<span style="color:#7F6C41;">{{ item.name }}を入手した!</span></span>
'''
a = r'''
{%\s+mobile_url\s+['"]{1}(/inventory/view_item/\?)[^'"]*['"]{1}\s+([^%}]+)\s+%}
'''
def aa(x):
print x.group(1)
print x.group(2)
return ''
string = re.sub(a, aa, string)
print string
and it show :
{% emoji 'MONEY_BAG' %}<span style="color:#7F6C41;">{{ item.name }}を入手した!</span></span>
i want to print the x.group(1) and the x.group(2)
so what can i do ,
thanks
It's a bad idea to use regex to extract information from HTML. It's much easier with a HMTL Parser: http://docs.python.org/library/htmlparser.html
Or if you want to crawl a webpage for more information, you might want to use scrapy which is a truly great web crawler framework.
Your extra newline characters in a are causing the regex to never match
a = r'''{%\s+mobile_url\s+['"]{1}(/inventory/view_item/\?)[^'"]*['"]{1}\s+([^%}]+)\s+%}'''
I have a string that is HTML encoded:
'''<img class="size-medium wp-image-113"\
style="margin-left: 15px;" title="su1"\
src="http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg"\
alt="" width="300" height="194" />'''
I want to change that to:
<img class="size-medium wp-image-113" style="margin-left: 15px;"
title="su1" src="http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg"
alt="" width="300" height="194" />
I want this to register as HTML so that it is rendered as an image by the browser instead of being displayed as text.
The string is stored like that because I am using a web-scraping tool called BeautifulSoup, it "scans" a web-page and gets certain content from it, then returns the string in that format.
I've found how to do this in C# but not in Python. Can someone help me out?
Related
Convert XML/HTML Entities into Unicode String in Python
With the standard library:
HTML Escape
try:
from html import escape # python 3.x
except ImportError:
from cgi import escape # python 2.x
print(escape("<"))
HTML Unescape
try:
from html import unescape # python 3.4+
except ImportError:
try:
from html.parser import HTMLParser # python 3.x (<3.4)
except ImportError:
from HTMLParser import HTMLParser # python 2.x
unescape = HTMLParser().unescape
print(unescape(">"))
Given the Django use case, there are two answers to this. Here is its django.utils.html.escape function, for reference:
def escape(html):
"""Returns the given HTML with ampersands, quotes and carets encoded."""
return mark_safe(force_unicode(html).replace('&', '&').replace('<', '&l
t;').replace('>', '>').replace('"', '"').replace("'", '''))
To reverse this, the Cheetah function described in Jake's answer should work, but is missing the single-quote. This version includes an updated tuple, with the order of replacement reversed to avoid symmetric problems:
def html_decode(s):
"""
Returns the ASCII decoded version of the given HTML string. This does
NOT remove normal HTML tags like <p>.
"""
htmlCodes = (
("'", '''),
('"', '"'),
('>', '>'),
('<', '<'),
('&', '&')
)
for code in htmlCodes:
s = s.replace(code[1], code[0])
return s
unescaped = html_decode(my_string)
This, however, is not a general solution; it is only appropriate for strings encoded with django.utils.html.escape. More generally, it is a good idea to stick with the standard library:
# Python 2.x:
import HTMLParser
html_parser = HTMLParser.HTMLParser()
unescaped = html_parser.unescape(my_string)
# Python 3.x:
import html.parser
html_parser = html.parser.HTMLParser()
unescaped = html_parser.unescape(my_string)
# >= Python 3.5:
from html import unescape
unescaped = unescape(my_string)
As a suggestion: it may make more sense to store the HTML unescaped in your database. It'd be worth looking into getting unescaped results back from BeautifulSoup if possible, and avoiding this process altogether.
With Django, escaping only occurs during template rendering; so to prevent escaping you just tell the templating engine not to escape your string. To do that, use one of these options in your template:
{{ context_var|safe }}
{% autoescape off %}
{{ context_var }}
{% endautoescape %}
For html encoding, there's cgi.escape from the standard library:
>> help(cgi.escape)
cgi.escape = escape(s, quote=None)
Replace special characters "&", "<" and ">" to HTML-safe sequences.
If the optional flag quote is true, the quotation mark character (")
is also translated.
For html decoding, I use the following:
import re
from htmlentitydefs import name2codepoint
# for some reason, python 2.5.2 doesn't have this one (apostrophe)
name2codepoint['#39'] = 39
def unescape(s):
"unescape HTML code refs; c.f. http://wiki.python.org/moin/EscapingHtml"
return re.sub('&(%s);' % '|'.join(name2codepoint),
lambda m: unichr(name2codepoint[m.group(1)]), s)
For anything more complicated, I use BeautifulSoup.
Use daniel's solution if the set of encoded characters is relatively restricted.
Otherwise, use one of the numerous HTML-parsing libraries.
I like BeautifulSoup because it can handle malformed XML/HTML :
http://www.crummy.com/software/BeautifulSoup/
for your question, there's an example in their documentation
from BeautifulSoup import BeautifulStoneSoup
BeautifulStoneSoup("Sacré bleu!",
convertEntities=BeautifulStoneSoup.HTML_ENTITIES).contents[0]
# u'Sacr\xe9 bleu!'
In Python 3.4+:
import html
html.unescape(your_string)
See at the bottom of this page at Python wiki, there are at least 2 options to "unescape" html.
Daniel's comment as an answer:
"escaping only occurs in Django during template rendering. Therefore, there's no need for an unescape - you just tell the templating engine not to escape. either {{ context_var|safe }} or {% autoescape off %}{{ context_var }}{% endautoescape %}"
If anyone is looking for a simple way to do this via the django templates, you can always use filters like this:
<html>
{{ node.description|safe }}
</html>
I had some data coming from a vendor and everything I posted had html tags actually written on the rendered page as if you were looking at the source.
I found a fine function at: http://snippets.dzone.com/posts/show/4569
def decodeHtmlentities(string):
import re
entity_re = re.compile("&(#?)(\d{1,5}|\w{1,8});")
def substitute_entity(match):
from htmlentitydefs import name2codepoint as n2cp
ent = match.group(2)
if match.group(1) == "#":
return unichr(int(ent))
else:
cp = n2cp.get(ent)
if cp:
return unichr(cp)
else:
return match.group()
return entity_re.subn(substitute_entity, string)[0]
Even though this is a really old question, this may work.
Django 1.5.5
In [1]: from django.utils.text import unescape_entities
In [2]: unescape_entities('<img class="size-medium wp-image-113" style="margin-left: 15px;" title="su1" src="http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg" alt="" width="300" height="194" />')
Out[2]: u'<img class="size-medium wp-image-113" style="margin-left: 15px;" title="su1" src="http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg" alt="" width="300" height="194" />'
I found this in the Cheetah source code (here)
htmlCodes = [
['&', '&'],
['<', '<'],
['>', '>'],
['"', '"'],
]
htmlCodesReversed = htmlCodes[:]
htmlCodesReversed.reverse()
def htmlDecode(s, codes=htmlCodesReversed):
""" Returns the ASCII decoded version of the given HTML string. This does
NOT remove normal HTML tags like <p>. It is the inverse of htmlEncode()."""
for code in codes:
s = s.replace(code[1], code[0])
return s
not sure why they reverse the list,
I think it has to do with the way they encode, so with you it may not need to be reversed.
Also if I were you I would change htmlCodes to be a list of tuples rather than a list of lists...
this is going in my library though :)
i noticed your title asked for encode too, so here is Cheetah's encode function.
def htmlEncode(s, codes=htmlCodes):
""" Returns the HTML encoded version of the given string. This is useful to
display a plain ASCII text string on a web page."""
for code in codes:
s = s.replace(code[0], code[1])
return s
You can also use django.utils.html.escape
from django.utils.html import escape
something_nice = escape(request.POST['something_naughty'])
Below is a python function that uses module htmlentitydefs. It is not perfect. The version of htmlentitydefs that I have is incomplete and it assumes that all entities decode to one codepoint which is wrong for entities like ≂̸:
http://www.w3.org/TR/html5/named-character-references.html
NotEqualTilde; U+02242 U+00338 ≂̸
With those caveats though, here's the code.
def decodeHtmlText(html):
"""
Given a string of HTML that would parse to a single text node,
return the text value of that node.
"""
# Fast path for common case.
if html.find("&") < 0: return html
return re.sub(
'&(?:#(?:x([0-9A-Fa-f]+)|([0-9]+))|([a-zA-Z0-9]+));',
_decode_html_entity,
html)
def _decode_html_entity(match):
"""
Regex replacer that expects hex digits in group 1, or
decimal digits in group 2, or a named entity in group 3.
"""
hex_digits = match.group(1) # '
' -> unichr(10)
if hex_digits: return unichr(int(hex_digits, 16))
decimal_digits = match.group(2) # '' -> unichr(0x10)
if decimal_digits: return unichr(int(decimal_digits, 10))
name = match.group(3) # name is 'lt' when '<' was matched.
if name:
decoding = (htmlentitydefs.name2codepoint.get(name)
# Treat > like >.
# This is wrong for ≫ and ≪ which HTML5 adopted from MathML.
# If htmlentitydefs included mappings for those entities,
# then this code will magically work.
or htmlentitydefs.name2codepoint.get(name.lower()))
if decoding is not None: return unichr(decoding)
return match.group(0) # Treat "&noSuchEntity;" as "&noSuchEntity;"
This is the easiest solution for this problem -
{% autoescape on %}
{{ body }}
{% endautoescape %}
From this page.
Searching the simplest solution of this question in Django and Python I found you can use builtin theirs functions to escape/unescape html code.
Example
I saved your html code in scraped_html and clean_html:
scraped_html = (
'<img class="size-medium wp-image-113" '
'style="margin-left: 15px;" title="su1" '
'src="http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg" '
'alt="" width="300" height="194" />'
)
clean_html = (
'<img class="size-medium wp-image-113" style="margin-left: 15px;" '
'title="su1" src="http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg" '
'alt="" width="300" height="194" />'
)
Django
You need Django >= 1.0
unescape
To unescape your scraped html code you can use django.utils.text.unescape_entities which:
Convert all named and numeric character references to the corresponding unicode characters.
>>> from django.utils.text import unescape_entities
>>> clean_html == unescape_entities(scraped_html)
True
escape
To escape your clean html code you can use django.utils.html.escape which:
Returns the given text with ampersands, quotes and angle brackets encoded for use in HTML.
>>> from django.utils.html import escape
>>> scraped_html == escape(clean_html)
True
Python
You need Python >= 3.4
unescape
To unescape your scraped html code you can use html.unescape which:
Convert all named and numeric character references (e.g. >, >, &x3e;) in the string s to the corresponding unicode characters.
>>> from html import unescape
>>> clean_html == unescape(scraped_html)
True
escape
To escape your clean html code you can use html.escape which:
Convert the characters &, < and > in string s to HTML-safe sequences.
>>> from html import escape
>>> scraped_html == escape(clean_html)
True