publik: use list/add filters to create list from simple values (#81223)

publik_django_templatetags/publik/templatetags/publik.py

@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import collections
 import datetime
 import math
 from decimal import Decimal
@@ -124,19 +125,35 @@ def decimal(value, arg=None):
 def add(term1, term2):
     '''replace the "add" native django filter'''
 
+    # consider None content as the empty string
     if term1 is None:
         term1 = ''
     if term2 is None:
         term2 = ''
-    term1_decimal = parse_decimal(term1, default=None)
-    term2_decimal = parse_decimal(term2, default=None)
 
-    if term1_decimal is not None and term2_decimal is not None:
-        return term1_decimal + term2_decimal
-    if term1 == '' and term2_decimal is not None:
-        return term2_decimal
-    if term2 == '' and term1_decimal is not None:
-        return term1_decimal
+    # return available number if the other term is the empty string
+    if term1 == '':
+        try:
+            return parse_decimal(term2, do_raise=True)
+        except (ArithmeticError, TypeError):
+            pass
+    if term2 == '':
+        try:
+            return parse_decimal(term1, do_raise=True)
+        except (ArithmeticError, TypeError):
+            pass
+
+    # compute addition if both terms are numbers
+    try:
+        return parse_decimal(term1, do_raise=True) + parse_decimal(term2, do_raise=True)
+    except (ArithmeticError, TypeError, ValueError):
+        pass
+
+    # append to term1 if term1 is a list and not term2
+    if isinstance(term1, list) and not isinstance(term2, list):
+        return list(term1) + [term2]
+
+    # fallback to django add filter
     return defaultfilters.add(term1, term2)
 
 
@@ -224,3 +241,12 @@ def duration(value, arg='short'):
         except (TypeError, ValueError):
             return ''
     return utils.seconds2humanduration(int(value.total_seconds()), short=bool(arg != 'long'))
+
+
+@register.filter(name='list')
+def list_(value):
+    # turn a generator into a list
+    if isinstance(value, collections.abc.Iterable) and not isinstance(value, (collections.abc.Mapping, str)):
+        return list(value)
+    else:
+        return [value]

tests/test_publik.py

@@ -1,3 +1,5 @@
+import html
+
 from django.template import Context, Template
 
 
@@ -409,3 +411,28 @@ def test_duration():
         Template('{{ value|duration:"long" }}').render(context)
         == '3 years, 1 month, 30 days, 15 hours and 46 minutes'
     )
+
+
+def test_convert_as_list():
+    tmpl = Template('{{ foo|list|first }}')
+    assert tmpl.render(Context({'foo': ['foo']})) == 'foo'
+
+    def list_generator():
+        yield from range(5)
+
+    assert tmpl.render(Context({'foo': list_generator})) == '0'
+
+    def list_range():
+        return range(5)
+
+    assert tmpl.render(Context({'foo': list_range})) == '0'
+
+
+def test_convert_as_list_with_add():
+    tmpl = Template('{{ foo|list|add:bar|join:", " }}')
+    assert tmpl.render(Context({'foo': [1, 2], 'bar': ['a', 'b']})) == '1, 2, a, b'
+    assert tmpl.render(Context({'foo': [1, 2], 'bar': 'ab'})) == '1, 2, ab'
+    assert tmpl.render(Context({'foo': 12, 'bar': ['a', 'b']})) == '12, a, b'
+    assert tmpl.render(Context({'foo': 12, 'bar': 'ab'})) == '12, ab'
+    assert html.unescape(tmpl.render(Context({'foo': [1, 2], 'bar': {'a': 'b'}}))) == "1, 2, {'a': 'b'}"
+    assert html.unescape(tmpl.render(Context({'foo': {'a': 'b'}, 'bar': ['a', 'b']}))) == "{'a': 'b'}, a, b"