Implement add BCF related topic

src/ifcblenderexport/blenderbim/bim/__init__.py

@@ -41,6 +41,7 @@ if bpy is not None:
         operator.AddBcfReferenceLink,
         operator.AddBcfDocumentReference,
         operator.AddBcfLabel,
+        operator.AddBcfRelatedTopic,
         operator.ViewBcfTopic,
         operator.RemoveBcfComment,
         operator.RemoveBcfBimSnippet,

src/ifcblenderexport/blenderbim/bim/operator.py

@@ -772,6 +772,29 @@ class AddBcfBimSnippet(bpy.types.Operator):
         return {"FINISHED"}
 
 
+class AddBcfRelatedTopic(bpy.types.Operator):
+    bl_idname = "bim.add_bcf_related_topic"
+    bl_label = "Add BCF Related Topic"
+
+    def execute(self, context):
+        bcfxml = bcfstore.BcfStore.get_bcfxml()
+        props = bpy.context.scene.BCFProperties
+        blender_topic = props.topics[props.active_topic_index]
+        related_topic = None
+        for topic in bcfxml.topics.values():
+            if topic.title == blender_topic.related_topic:
+                related_topic = bcf.data.RelatedTopic()
+                related_topic.guid = topic.guid
+                break
+        if not related_topic:
+            return {"FINISHED"}
+        topic = bcfxml.topics[blender_topic.name]
+        topic.related_topics.append(related_topic)
+        bcfxml.edit_topic(topic)
+        bpy.ops.bim.load_bcf_topic(topic_guid = topic.guid, topic_index = props.active_topic_index)
+        return {"FINISHED"}
+
+
 class AddBcfHeaderFile(bpy.types.Operator):
     bl_idname = "bim.add_bcf_header_file"
     bl_label = "Add BCF Header File"

src/ifcblenderexport/blenderbim/bim/prop.py

@@ -1044,6 +1044,7 @@ class BcfTopic(PropertyGroup):
     document_reference: StringProperty(default="", name="Referenced Document")
     document_reference_description: StringProperty(default="", name="Description")
     related_topics: CollectionProperty(name="Related Topics", type=StrProperty)
+    related_topic: StringProperty(default="", name="Related Topic")
     comments: CollectionProperty(name="Comments", type=BcfComment)
     is_editable: BoolProperty(name="Is Editable", default=False, update=updateBcfTopicIsEditable)
     comment: StringProperty(default="", name="Comment")

src/ifcblenderexport/blenderbim/bim/ui.py

@@ -1864,6 +1864,10 @@ class BIM_PT_bcf_metadata(Panel):
             row = layout.row(align=True)
             row.operator("bim.view_bcf_topic", text=bcfxml.topics[related_topic.name.lower()].title).topic_guid = related_topic.name
             row.operator("bim.remove_bcf_related_topic", icon="X", text="").index = index
+        row = layout.row()
+        row.prop(topic, "related_topic")
+        row = layout.row()
+        row.operator("bim.add_bcf_related_topic")
 
 
 class BIM_PT_bcf_comments(Panel):