Changed by_taxonomy to create term if open

If the taxonomy has an open vocabulary, we create missing terms
rather than throw an exception

django/website/taxonomies/models.py

@@ -60,7 +60,7 @@ class Taxonomy(models.Model):
 class TermManager(models.Manager):
 
     def by_taxonomy(self, taxonomy, name):
-        """ Fetch an existing  Term by its name and its
+        """ Fetch a Term by its name and its
         Taxonomy slug which, together should be unique together.
 
         args:
@@ -73,21 +73,30 @@ class TermManager(models.Manager):
             The term object with the given name in the given Taxonomy.
 
         throws:
-            DoesNotExist if no Term matches the given combination
+            DoesNotExist if Taxonomy with the given slug does not exist
+            DoesNotExist if named Term does not exist, unless the Taxonomy
+            vocabulary is open - in this case the Term will be created
             ValueError if taxonomy is not one of the allowed types
         """
         if isinstance(taxonomy, basestring):
-            taxonomy_slug = taxonomy
-        elif isinstance(taxonomy, Taxonomy):
-            taxonomy_slug = taxonomy.slug
-        else:
+            taxonomy = Taxonomy.objects.get(slug=taxonomy)
+        elif not isinstance(taxonomy, Taxonomy):
             raise ValueError(
                 "taxonomy must be a Taxonomy instance "
                 "or a valid taxonomy slug")
-        return self.select_related('taxonomy').get(
-            taxonomy__slug=taxonomy_slug,
-            name=name
-        )
+
+        if taxonomy.is_open:
+            term, _ = self.select_related('taxonomy').get_or_create(
+                taxonomy=taxonomy,
+                name=name
+            )
+        else:
+            term = self.select_related('taxonomy').get(
+                taxonomy=taxonomy,
+                name=name
+            )
+
+        return term
 
 
 class Term(models.Model):

django/website/taxonomies/tests/term_tests.py

@@ -35,3 +35,29 @@ def test_term_by_taxonomy_with_taxonomies_with_taxonomy(term_with_context):
 
     assert term.name == term_with_context.name
     assert term.taxonomy == term_with_context.taxonomy
+
+
+@pytest.mark.django_db
+def test_unknown_term_by_taxonomy_creates_term_if_open():
+    taxonomy = TaxonomyFactory(vocabulary='open')
+
+    term = Term.objects.by_taxonomy(
+        taxonomy=taxonomy,
+        name="a term that doesn't exist",
+    )
+
+    assert term.name == "a term that doesn't exist"
+    assert term.taxonomy == taxonomy
+
+
+@pytest.mark.django_db
+def test_unknown_term_by_taxonomy_throws_exception_if_not_open():
+    taxonomy = TaxonomyFactory(vocabulary='closed')
+
+    with pytest.raises(Term.DoesNotExist) as excinfo:
+        Term.objects.by_taxonomy(
+            taxonomy=taxonomy,
+            name="a term that doesn't exist",
+        )
+
+    assert excinfo.value.message == "Term matching query does not exist."