Add class attribute to change the graph direction (#90)

Co-authored-by: Johannes Maron <johannes@maron.family>

docs/core_components.rst

@@ -46,6 +46,7 @@ Advanced Workflow API
     :show-inheritance:
     :members:
         urls,
+        rankdir,
         get_graph_svg,
         get_instance_graph_svg,
         get_absolute_url,

joeflow/models.py

@@ -66,6 +66,9 @@ class Workflow(models.Model, metaclass=WorkflowBase):
     created = models.DateTimeField(auto_now_add=True, db_index=True)
     modified = models.DateTimeField(auto_now=True, db_index=True)
 
+    rankdir = "LR"
+    """Direction of the workflow's graph visualization."""
+
     task_set = GenericRelation(
         "joeflow.Task", object_id_field="_workflow_id", for_concrete_model=False
     )
@@ -194,7 +197,7 @@ def get_graph(cls, color="black"):
 
         """
         graph = NoDashDiGraph()
-        graph.attr("graph", rankdir="LR")
+        graph.attr("graph", rankdir=cls.rankdir)
         graph.attr(
             "node",
             _attributes=dict(

tests/test_models.py

@@ -111,6 +111,11 @@ def test_get_graph(self, fixturedir):
         print(str(graph))
         assert set(str(graph).splitlines()) == set(expected_graph)
 
+    def test_change_graph_direction(self, fixturedir):
+        workflows.SimpleWorkflow.rankdir = "TD"
+        graph = workflows.SimpleWorkflow.get_graph()
+        assert "rankdir=TD" in str(graph)
+
     def test_get_graph_svg(self, fixturedir):
         svg = workflows.SimpleWorkflow.get_graph_svg()
         assert isinstance(svg, SafeString)