create graph only once

qiita_pet/handlers/analysis_handlers/base_handlers.py

@@ -175,26 +175,26 @@ def analyisis_graph_handler_get_request(analysis_id, user):
     edges = []
     artifacts_being_deleted = []
     wf_id = None
-    # Loop through all the initial artifacts of the analysis
-    for a in analysis.artifacts:
-        if a.processing_parameters is None:
-            g = a.descendants_with_jobs
-            nodes, edges, a_wf_id = get_network_nodes_edges(
-                g, full_access, nodes=nodes, edges=edges)
-
-            # nodes returns [node_type, node_name, element_id]; here we
-            # are looking for the node_type == artifact, and check by
-            # the element/artifact_id if it's being deleted
-            for a in nodes:
-                if (a[0] == 'artifact' and
-                        Artifact(a[2]).being_deleted_by is not None):
-                    artifacts_being_deleted.append(a[2])
-
-            if wf_id is None:
-                wf_id = a_wf_id
-            elif a_wf_id is not None and wf_id != a_wf_id:
-                # This should never happen, but worth having a useful message
-                raise ValueError('More than one workflow in a single analysis')
+    # Let's take the first artifact without processing_parameters (which makes
+    # it a root) and the rest of the work is done by descendants_with_jobs
+    a = [a for a in analysis.artifacts if a.processing_parameters is None][0]
+    g = a.descendants_with_jobs
+    nodes, edges, a_wf_id = get_network_nodes_edges(
+        g, full_access, nodes=nodes, edges=edges)
+
+    # nodes returns [node_type, node_name, element_id]; here we
+    # are looking for the node_type == artifact, and check by
+    # the element/artifact_id if it's being deleted
+    for a in nodes:
+        if (a[0] == 'artifact' and
+                Artifact(a[2]).being_deleted_by is not None):
+            artifacts_being_deleted.append(a[2])
+
+    if wf_id is None:
+        wf_id = a_wf_id
+    elif a_wf_id is not None and wf_id != a_wf_id:
+        # This should never happen, but worth having a useful message
+        raise ValueError('More than one workflow in a single analysis')
 
     return {'edges': edges, 'nodes': nodes, 'workflow': wf_id,
             'artifacts_being_deleted': artifacts_being_deleted}