[core][graphIO] Add "template" as an explicit key

meshroom/core/graph.py

@@ -279,7 +279,7 @@ class Graph(BaseObject):
         self.header = graphData.get(GraphIO.Keys.Header, {})
         fileVersion = Version(self.header.get(GraphIO.Keys.FileVersion, "0.0"))
         graphContent = self._normalizeGraphContent(graphData, fileVersion)
-        isTemplate = self.header.get("template", False)
+        isTemplate = self.header.get(GraphIO.Keys.Template, False)
 
         with GraphModification(self):
             # iterate over nodes sorted by suffix index in their names
@@ -337,7 +337,7 @@ class Graph(BaseObject):
         #   3. fallback behavior: default to "0.0"
         if "version" not in nodeData:
             nodeData["version"] = fromGraph._getNodeTypeVersionFromHeader(nodeData["nodeType"], "0.0")
-        inTemplate = fromGraph.header.get("template", False)
+        inTemplate = fromGraph.header.get(GraphIO.Keys.Template, False)
         node = nodeFactory(nodeData, nodeName, inTemplate=inTemplate)
         self._addNode(node, nodeName)
         return node

meshroom/core/graphIO.py

@@ -24,6 +24,7 @@ class GraphIO:
         ReleaseVersion = "releaseVersion"
         FileVersion = "fileVersion"
         Graph = "graph"
+        Template = "template"
 
     class Features(Enum):
         """File Features."""
@@ -122,7 +123,7 @@ class TemplateGraphSerializer(GraphSerializer):
 
     def serializeHeader(self) -> dict:
         header = super().serializeHeader()
-        header["template"] = True
+        header[GraphIO.Keys.Template] = True
         return header
 
     def serializeNode(self, node: Node) -> dict: