Hide assign/unassign library declaration button for elements that cannot be declared

E.g. IfcMaterials, IfcProfileDefs

src/bonsai/bonsai/bim/module/project/operator.py

@@ -271,10 +271,21 @@ class ChangeLibraryElement(bpy.types.Operator):
         new.name = name
         new.ifc_definition_id = ifc_definition_id
         element = self.library_file.by_id(ifc_definition_id)
-        if self.library_file.schema == "IFC2X3" or not self.library_file.by_type("IfcProjectLibrary"):
+
+        # is_declarable.
+        project_libraries_exist = bool(
+            self.library_file.schema != "IFC2X3" and self.library_file.by_type("IfcProjectLibrary")
+        )
+        is_declarable = project_libraries_exist and element.is_a("IfcObjectDefinition")
+        new.is_declarable = is_declarable
+
+        # is_declared.
+        if not is_declarable:
             new.is_declared = False
-        elif getattr(element, "HasContext", None) and element.HasContext[0].RelatingContext.is_a("IfcProjectLibrary"):
+        elif (has_context := element.HasContext) and has_context[0].RelatingContext.is_a("IfcProjectLibrary"):
             new.is_declared = True
+
+        # is_appended.
         try:
             if element.is_a("IfcMaterial"):
                 next(e for e in self.file.by_type("IfcMaterial") if e.Name == name)

src/bonsai/bonsai/bim/module/project/prop.py

@@ -103,12 +103,18 @@ class LibraryElement(PropertyGroup):
     ifc_definition_id: IntProperty(name="IFC Definition ID")
     is_declared: BoolProperty(name="Is Declared", default=False)
     is_appended: BoolProperty(name="Is Appended", default=False)
+    is_declarable: BoolProperty(
+        name="Is Declarable",
+        description="Whether element support being declared as part of IfcProjectLibrary",
+        default=False,
+    )
 
     if TYPE_CHECKING:
         name: str
         ifc_definition_id: int
         is_declared: bool
         is_appended: bool
+        is_declarable: bool
 
 
 class FilterCategory(PropertyGroup):

src/bonsai/bonsai/bim/module/project/ui.py

@@ -24,7 +24,7 @@ import bonsai.tool as tool
 from bonsai.bim.helper import prop_with_search
 from bpy.types import Panel, Menu, UIList
 from bonsai.bim.ifc import IfcStore
-from bonsai.bim.module.project.data import ProjectData, LinksData, ProjectLibraryData
+from bonsai.bim.module.project.data import ProjectData, LinksData
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
@@ -463,9 +463,7 @@ class BIM_UL_library(UIList):
                 op = row.operator("bim.change_library_element", text="", icon="DISCLOSURE_TRI_RIGHT", emboss=False)
                 op.element_name = item.name
             row.label(text=item.name)
-            if not ProjectLibraryData.is_loaded:
+            if item.ifc_definition_id and item.is_declarable:
-                ProjectLibraryData.load()
-            if item.ifc_definition_id and ProjectLibraryData.data["project_libraries"]:
                 if item.is_declared:
                     op = row.operator("bim.unassign_library_declaration", text="", icon="KEYFRAME_HLT", emboss=False)
                     op.definition = item.ifc_definition_id