Ticket #5025: truncate.patch

django/template/defaultfilters.py

@@ -144 +144 @@
     return re.sub("([a-z])'([A-Z])", lambda m: m.group(0).lower(), value.title())
 title = stringfilter(title)
 
+def truncate(value, limit):
+    """
+    Truncates strings longer than limit to limit-3 characters, appending an
+    elipsis.
+    
+    Argument: Number of characters to truncate to
+    """
+    from django.utils.text import truncate
+    try:
+        limit = int(limit)
+    except ValueError: # invalid literal for int()
+        return value # Fail silently.
+    return truncate(value, limit)
+truncate = stringfilter(truncate)
+
 def truncatewords(value, arg):
     """
     Truncates a string after a certain number of words
@@ -600 +615 @@
 register.filter(timesince)
 register.filter(timeuntil)
 register.filter(title)
+register.filter(truncate)
 register.filter(truncatewords)
 register.filter(truncatewords_html)
 register.filter(unordered_list)

django/utils/html.py

@@ -5 +5 @@
 
 from django.utils.encoding import force_unicode
 from django.utils.functional import allow_lazy
+from django.utils.text import truncate
 
 # Configuration for urlize() function
 LEADING_PUNCTUATION  = ['(', '<', '&lt;']
@@ -72 +73 @@
     If nofollow is True, the URLs in link text will get a rel="nofollow"
     attribute.
     """
-    trim_url = lambda x, limit=trim_url_limit: limit is not None and (len(x) > limit and ('%s...' % x[:max(0, limit - 3)])) or x
+    trim_url = lambda x, limit=trim_url_limit: truncate(x, limit)
     words = word_split_re.split(force_unicode(text))
     nofollow_attr = nofollow and ' rel="nofollow"' or ''
     for i, word in enumerate(words):

django/utils/text.py

@@ -35 +35 @@
     return u''.join(_generator())
 wrap = allow_lazy(wrap, unicode)
 
+def truncate(s, limit):
+    """
+    Truncates strings longer than limit to limit-3 characters, appending an
+    elipsis. At least one character will always be displayed, so the functional
+    minimum limit is 4.
+    """
+    s = force_unicode(s)
+    if len(s) <= limit:
+        return s
+    return '%s...' % s[:max(1, limit - 3)]
+truncate = allow_lazy(truncate, unicode)
+
 def truncate_words(s, num):
     "Truncates a string after a certain number of words."
     s = force_unicode(s)

docs/templates.txt

@@ -1272 +1272 @@
 
 Converts a string into titlecase.
 
+truncate
+~~~~~~~~
+
+Ensures a string is no longer than the given character limit, truncating to
+limit-3 characters and appending an elipsis for strings which exceed this limit.
+For example, if ``email`` contains ``'info@example.com'``, then
+``{{ email|truncate:10 }}`` will return "``info@ex...``".
+
+**Argument:** Length to truncate string to
+
 truncatewords
 ~~~~~~~~~~~~~
 
-Truncates a string after a certain number of words.
+Truncates a string to a certain number of words, also appending an elipsis to
+strings which exceed this number of words.
 
 **Argument:** Number of words to truncate after
 

tests/regressiontests/defaultfilters/tests.py

@@ -82 +82 @@
 >>> title(u'discoth\xe8que')
 u'Discoth\xe8que'
 
+>>> truncate(u'A sentence with a few words in it', 2)
+u'A...'
+
+>>> truncate(u'A sentence with a few words in it', 6)
+u'A s...'
+
+>>> truncate(u'A sentence with a few words in it', 10)
+u'A sente...'
+
+>>> truncate(u'A sentence with a few words in it', 100)
+u'A sentence with a few words in it'
+
+>>> truncate(u'A sentence with a few words in it', 'not a number')
+u'A sentence with a few words in it'
+
 >>> truncatewords(u'A sentence with a few words in it', 1)
 u'A ...'