templatetags: make count an alias of length (#49889)

tests/test_formdata.py

@@ -1157,6 +1157,8 @@ def test_lazy_formdata_queryset_filter(pub, variable_test_data):
     context = pub.substitutions.get_context_variables(mode='lazy')
     tmpl = Template('{{form_objects|filter_by:"foo_foo"|filter_value:"bar"|count}}')
     assert tmpl.render(context) == '7'
+    tmpl = Template('{{form_objects|filter_by:"foo_foo"|filter_value:"bar"|length}}')
+    assert tmpl.render(context) == '7'
 
     pub.substitutions.feed(formdata)
     tmpl = Template('{{form_objects|filter_by:"foo_foo"|filter_value:form_var_foo_foo|count}}')
@@ -2291,6 +2293,24 @@ def test_lazy_formdata_ceil_filter(pub):
         assert tmpl.render(context) == '3.14'
 
 
+def test_lazy_formdata_count_as_len_filter(pub):
+    formdef = FormDef()
+    formdef.name = 'foobar'
+    formdef.url_name = 'foobar'
+    formdef.fields = [
+        fields.StringField(id='0', label='value', varname='value'),
+    ]
+    formdef.store()
+    formdata = formdef.data_class()()
+    formdata.data = {'0': 'coin'}
+    formdata.store()
+    pub.substitutions.feed(formdata)
+    for mode in (None, 'lazy'):
+        context = pub.substitutions.get_context_variables(mode=mode)
+        tmpl = Template('{{ form_var_value|count }}')
+        assert tmpl.render(context) == '4'
+
+
 def test_rounding_and_abs_conditions_django(pub, variable_test_data):
     for true_condition_value in (
             # reminder

wcs/qommon/templatetags/qommon.py

@@ -670,7 +670,9 @@ def filter_value(queryset, value):
 
 @register.filter
 def count(queryset):
-    return queryset.count
+    if hasattr(queryset, 'get_value'):
+        queryset = queryset.get_value()  # unlazy
+    return len(queryset)
 
 
 @register.filter