Access stylesheet from Presentation

gaphor/core/modeling/__init__.py

@@ -7,4 +7,4 @@ from gaphor.core.modeling.coremodel import (
 from gaphor.core.modeling.diagram import Diagram
 from gaphor.core.modeling.elementfactory import ElementFactory
 from gaphor.core.modeling.event import *
-from gaphor.core.modeling.presentation import Presentation
+from gaphor.core.modeling.presentation import Presentation, Stylesheet

gaphor/core/modeling/coremodel.py

@@ -37,11 +37,11 @@ class PackageableElement(NamedElement):
     pass
 
 
-# 49: override Diagram
+# 55: override Diagram
 # defined in gaphor.core.modeling.diagram
 
 
-# 40: override Presentation
+# 46: override Presentation
 # defined in gaphor.core.modeling.presentation
 
 
@@ -50,17 +50,19 @@ class Comment(Element):
     annotatedElement: relation_many[Element]
 
 
-class Stylesheet(Element):
-    stylesheet: attribute[str]
+# 40: override Stylesheet
+# defined in gaphor.core.modeling.presentation
 
 
 NamedElement.name = attribute("name", str)
 Comment.body = attribute("body", str)
-Stylesheet.stylesheet = attribute("stylesheet", str)
-# 46: override Presentation.subject
+# 43: override Stylesheet.stylesheet
 # defined in gaphor.core.modeling.presentation
 
-# 43: override Element.presentation
+# 52: override Presentation.subject
+# defined in gaphor.core.modeling.presentation
+
+# 49: override Element.presentation
 # defined in gaphor.core.modeling.presentation
 
 Comment.annotatedElement = association(

gaphor/core/modeling/presentation.py

@@ -7,7 +7,7 @@ from __future__ import annotations
 from typing import TYPE_CHECKING, Callable, Generic, List, Optional, TypeVar
 
 from gaphor.core.modeling import Element
-from gaphor.core.modeling.properties import association, relation_one
+from gaphor.core.modeling.properties import association, attribute, relation_one
 
 if TYPE_CHECKING:
     from gaphas.canvas import Canvas  # noqa
@@ -17,6 +17,10 @@ if TYPE_CHECKING:
 S = TypeVar("S", bound=Element)
 
 
+class Stylesheet(Element):
+    stylesheet: attribute[str] = attribute("stylesheet", str)
+
+
 class Presentation(Element, Generic[S]):
     """
     This presentation is used to link the behaviors of `gaphor.core.modeling` and `gaphas.Item`.
@@ -77,6 +81,10 @@ class Presentation(Element, Generic[S]):
             self.canvas.remove(self)
         super().unlink()
 
+    @property
+    def stylesheet(self):
+        return next(self.model.select(lambda e: isinstance(e, Stylesheet)), None)
+
 
 Element.presentation = association(
     "presentation", Presentation, composite=True, opposite="subject"

gaphor/core/modeling/tests/test_presentation.py

@@ -0,0 +1,35 @@
+import pytest
+from gaphas.item import Item
+
+from gaphor.core.eventmanager import EventManager
+from gaphor.core.modeling.diagram import Diagram
+from gaphor.core.modeling.elementfactory import ElementFactory
+from gaphor.core.modeling.presentation import Presentation, Stylesheet
+
+
+class StubItem(Presentation, Item):
+    pass
+
+
+@pytest.fixture
+def element_factory():
+    event_manager = EventManager()
+    return ElementFactory(event_manager)
+
+
+@pytest.fixture
+def diagram(element_factory):
+    return element_factory.create(Diagram)
+
+
+def test_presentation_stylesheet(diagram, element_factory):
+    stylesheet = element_factory.create(Stylesheet)
+    presentation = diagram.create(StubItem)
+
+    assert presentation.stylesheet is stylesheet
+
+
+def test_presentation_stylesheet_is_absent(diagram):
+    presentation = diagram.create(StubItem)
+
+    assert presentation.stylesheet is None

models/Core.override

@@ -37,6 +37,12 @@ NamedElement.qualifiedName = derived(
     lambda obj: [_namedelement_qualifiedname(obj)],
 )
 %%
+override Stylesheet
+# defined in gaphor.core.modeling.presentation
+%%
+override Stylesheet.stylesheet
+# defined in gaphor.core.modeling.presentation
+%%
 override Presentation
 # defined in gaphor.core.modeling.presentation
 %%