问题

I have a string that is HTML encoded:

'''&lt;img class=&quot;size-medium wp-image-113&quot;\
 style=&quot;margin-left: 15px;&quot; title=&quot;su1&quot;\
 src=&quot;http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg&quot;\
 alt=&quot;&quot; width=&quot;300&quot; height=&quot;194&quot; /&gt;'''

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?

Convert XML/HTML Entities into Unicode String in Python

回答1:

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('&', '&amp;').replace('<', '&l
t;').replace('>', '&gt;').replace('"', '&quot;').replace("'", '&#39;'))

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 = (
            ("'", '&#39;'),
            ('"', '&quot;'),
            ('>', '&gt;'),
            ('<', '&lt;'),
            ('&', '&amp;')
        )
    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 %}

回答2:

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("&gt;"))

回答3:

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.

回答4:

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("Sacr&eacute; bl&#101;u!", 
                   convertEntities=BeautifulStoneSoup.HTML_ENTITIES).contents[0]
# u'Sacr\xe9 bleu!'

回答5:

In Python 3.4+:

import html

html.unescape(your_string)

回答6:

See at the bottom of this page at Python wiki, there are at least 2 options to "unescape" html.

回答7:

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 %}"

回答8:

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]

回答9:

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. The above code helped me greatly. Hope this helps others.

Cheers!!

回答10:

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('&lt;img class=&quot;size-medium wp-image-113&quot; style=&quot;margin-left: 15px;&quot; title=&quot;su1&quot; src=&quot;http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg&quot; alt=&quot;&quot; width=&quot;300&quot; height=&quot;194&quot; /&gt;')
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" />'

回答11:

I found this in the Cheetah source code (here)

htmlCodes = [
    ['&', '&amp;'],
    ['<', '&lt;'],
    ['>', '&gt;'],
    ['"', '&quot;'],
]
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

回答12:

You can also use django.utils.html.escape

from django.utils.html import escape

something_nice = escape(request.POST['something_naughty'])

回答13:

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 &NotEqualTilde;:

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)  # '&#10;' -> unichr(10)
    if hex_digits: return unichr(int(hex_digits, 16))
    decimal_digits = match.group(2)  # '&#x10;' -> unichr(0x10)
    if decimal_digits: return unichr(int(decimal_digits, 10))
    name = match.group(3)  # name is 'lt' when '&lt;' was matched.
    if name:
        decoding = (htmlentitydefs.name2codepoint.get(name)
            # Treat &GT; like &gt;.
            # This is wrong for &Gt; and &Lt; 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;"

回答14:

This is the easiest solution for this problem -

{% autoescape on %}
   {{ body }}
{% endautoescape %}

From this page.

回答15:

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 = (
    '&lt;img class=&quot;size-medium wp-image-113&quot; '
    'style=&quot;margin-left: 15px;&quot; title=&quot;su1&quot; '
    'src=&quot;http://blah.org/wp-content/uploads/2008/10/su1-300x194.jpg&quot; '
    'alt=&quot;&quot; width=&quot;300&quot; height=&quot;194&quot; /&gt;'
)
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

来源：https://stackoverflow.com/questions/275174/how-do-i-perform-html-decoding-encoding-using-python-django

标签

python

django

html-encode

How do I perform HTML decoding/encoding using Python/Django?

问题

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回答15:

Example

Django

unescape

escape

Python

unescape

escape