templatetags: introduce |list, to turn a generator into a list (#54807)

tests/test_templates.py

@@ -1174,3 +1174,19 @@ def test_is_empty():
     assert tmpl.render({'foo': ['foo']}) == 'False'
     assert tmpl.render({'foo': {}}) == 'True'
     assert tmpl.render({'foo': {'foo': 42}}) == 'False'
+
+
+def test_convert_as_list():
+    tmpl = Template('{{ foo|list|first }}')
+    assert tmpl.render({'foo': ['foo']}) == 'foo'
+
+    def list_generator():
+        for i in range(5):
+            yield i
+
+    assert tmpl.render({'foo': list_generator}) == '0'
+
+    def list_range():
+        return range(5)
+
+    assert tmpl.render({'foo': list_range}) == '0'

wcs/qommon/templatetags/qommon.py

@@ -791,3 +791,9 @@ def is_empty(value):
 @register.filter
 def strip_metadata(value):
     return unlazy(value).strip_metadata()
+
+
+@register.filter(name='list')
+def list_(value):
+    # turn a generator into a list
+    return list(unlazy(value))