From 1512a8096b1e7d2e3c570675e42ae7086da32fdd Mon Sep 17 00:00:00 2001
From: Ghostkeeper <rubend@tutanota.com>
Date: Mon, 12 Mar 2018 15:43:25 +0100
Subject: [PATCH] Require MaterialGroup to always have a base material

The material group is loaded lazily whenever the base material is not yet in the dictionary.

Contributes to issue CURA-4606.
---
 cura/Machines/MaterialGroup.py   | 11 ++++++-----
 cura/Machines/MaterialManager.py | 16 +++++++---------
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/cura/Machines/MaterialGroup.py b/cura/Machines/MaterialGroup.py
index 009778943a..07b790c6bc 100644
--- a/cura/Machines/MaterialGroup.py
+++ b/cura/Machines/MaterialGroup.py
@@ -1,9 +1,10 @@
 # Copyright (c) 2018 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
+from typing import List
+from cura.Machines.MaterialNode import MaterialNode #For type checking.
 
-#
-# A MaterialGroup represents a group of material InstanceContainers that are derived from a single material profile.
+## A MaterialGroup represents a group of material InstanceContainers that are derived from a single material profile.
 # The main InstanceContainer which has the ID of the material profile file name is called the "root_material". For
 # example: "generic_abs" is the root material (ID) of "generic_abs_ultimaker3" and "generic_abs_ultimaker3_AA_0.4",
 # and "generic_abs_ultimaker3" and "generic_abs_ultimaker3_AA_0.4" are derived materials of "generic_abs".
@@ -17,10 +18,10 @@
 class MaterialGroup:
     __slots__ = ("name", "root_material_node", "derived_material_node_list")
 
-    def __init__(self, name: str):
+    def __init__(self, name: str, root_material_node: MaterialNode):
         self.name = name
-        self.root_material_node = None
-        self.derived_material_node_list = []
+        self.root_material_node = root_material_node
+        self.derived_material_node_list = [] #type: List[MaterialNode]
 
     def __str__(self) -> str:
         return "%s[%s]" % (self.__class__.__name__, self.name)
diff --git a/cura/Machines/MaterialManager.py b/cura/Machines/MaterialManager.py
index 7c205c0084..b01d360ab6 100644
--- a/cura/Machines/MaterialManager.py
+++ b/cura/Machines/MaterialManager.py
@@ -72,29 +72,27 @@ class MaterialManager(QObject):
 
     def initialize(self):
         # Find all materials and put them in a matrix for quick search.
-        material_metadata_list = self._container_registry.findContainersMetadata(type = "material")
+        material_metadatas = {metadata["id"]: metadata for metadata in self._container_registry.findContainersMetadata(type = "material")}
 
         self._material_group_map = dict()
 
         # Map #1
         #    root_material_id -> MaterialGroup
-        for material_metadata in material_metadata_list:
-            material_id = material_metadata["id"]
+        for material_id, material_metadata in material_metadatas.items():
             # We don't store empty material in the lookup tables
             if material_id == "empty_material":
                 continue
 
             root_material_id = material_metadata.get("base_file")
             if root_material_id not in self._material_group_map:
-                self._material_group_map[root_material_id] = MaterialGroup(root_material_id)
+                self._material_group_map[root_material_id] = MaterialGroup(root_material_id, MaterialNode(material_metadatas[root_material_id]))
             group = self._material_group_map[root_material_id]
 
-            # We only add root materials here
-            if material_id == root_material_id:
-                group.root_material_node = MaterialNode(material_metadata)
-            else:
+            #Store this material in the group of the appropriate root material.
+            if material_id != root_material_id:
                 new_node = MaterialNode(material_metadata)
                 group.derived_material_node_list.append(new_node)
+
         # Order this map alphabetically so it's easier to navigate in a debugger
         self._material_group_map = OrderedDict(sorted(self._material_group_map.items(), key = lambda x: x[0]))
 
@@ -179,7 +177,7 @@ class MaterialManager(QObject):
         #    "machine" -> "variant_name" -> "root material ID" -> specific material InstanceContainer
         # Construct the "machine" -> "variant" -> "root material ID" -> specific material InstanceContainer
         self._diameter_machine_variant_material_map = dict()
-        for material_metadata in material_metadata_list:
+        for material_metadata in material_metadatas.values():
             # We don't store empty material in the lookup tables
             if material_metadata["id"] == "empty_material":
                 continue