feat(DeploymentView): add ability to add a relationship to the view

Author: yt-ms

src/structurizr/view/deployment_view.py

@@ -76,13 +76,12 @@ def add_all_deployment_nodes(self):
         If the environment is set in this view, then only nodes from the same
         environment will be added.
         """
-        for deployment_node in self.model.deployment_nodes:
-            if deployment_node.parent is None:
-                if (
-                    self.environment is None
-                    or self.environment == deployment_node.environment
-                ):
-                    self.add(deployment_node)
+        for deployment_node in self.model.deployment_nodes:  # This returns top-level
+            if (
+                self.environment is None
+                or self.environment == deployment_node.environment
+            ):
+                self.add(deployment_node)
 
     def add(
         self, item: Union[DeploymentNode, Relationship], add_relationships: bool = True
@@ -95,9 +94,9 @@ def add(
                     self._add_element(parent, add_relationships)
                     parent = parent.parent
         else:
-            pass  # TODO
+            self._add_relationship(item)
 
-    def __iadd__(self, item: Union[DeploymentNode, Relationship]):
+    def __iadd__(self, item: Union[DeploymentNode, Relationship]) -> "DeploymentView":
         """Add a deployment node or relationship to this view."""
         self.add(item)
         return self

src/structurizr/view/view.py

@@ -24,7 +24,7 @@
 from ..abstract_base import AbstractBase
 from ..base_model import BaseModel
 from ..mixin import ViewSetRefMixin
-from ..model import Element, Model, SoftwareSystem
+from ..model import Element, Model, Relationship, SoftwareSystem
 from .automatic_layout import AutomaticLayout, AutomaticLayoutIO
 from .element_view import ElementView, ElementViewIO
 from .paper_size import PaperSize
@@ -169,6 +169,21 @@ def _remove_element(self, element: Element) -> None:
             ):
                 self.relationship_views.remove(relationship_view)
 
+    def _add_relationship(self, relationship: Relationship) -> RelationshipView:
+        """Add a single relationship to this view.
+
+        Returns:
+            The new view if both the source and destination for the relationship are
+            in this view, else `None`.
+        """
+        if self.is_element_in_view(relationship.source) and self.is_element_in_view(
+            relationship.destination
+        ):
+            view = RelationshipView(relationship=relationship)
+            self.relationship_views.add(view)
+            return view
+        return None
+
     def _add_relationships(self, element: Element) -> None:
         """
         Add all relationships involving the given element to this view.

tests/unit/view/test_deployment_view.py

@@ -114,7 +114,7 @@ def test_deployment_view_add_all_deployment_nodes_with_container_instances(
         key="deployment",
         description="Description",
     )
-    deployment_view.add_all_deployment_nodes()
+    deployment_view.add_default_elements()
     element_views = deployment_view.element_views
     assert len(element_views) == 2
     assert any([x.element is deployment_node for x in element_views])
@@ -196,6 +196,34 @@ def test_deployment_view_add_deployment_node_adds_parent(empty_workspace: Worksp
     assert any([x.element is container_instance for x in element_views])
 
 
+def test_deployment_view_add_relationship(empty_workspace: Workspace):
+    """Check adding a relationship to the deployment view."""
+    model = empty_workspace.model
+    software_system = model.add_software_system("Software System")
+    container1 = software_system.add_container("Container1")
+    container2 = software_system.add_container("Container2")
+    rel = container1.uses(container2)
+    parent_deployment_node = model.add_deployment_node("Deployment Node")
+    child_deployment_node1 = parent_deployment_node.add_deployment_node("Child1")
+    child_deployment_node1 += container1
+    child_deployment_node2 = parent_deployment_node.add_deployment_node("Child2")
+    child_deployment_node2 += container2
+
+    deployment_view = empty_workspace.views.create_deployment_view(
+        software_system=software_system, key="deployment", description="Description"
+    )
+    deployment_view += child_deployment_node1
+
+    # First try before we have the destination in the view
+    deployment_view += rel
+    assert len(deployment_view.relationship_views) == 0
+
+    # Now try with it in
+    deployment_view += child_deployment_node2
+    deployment_view += rel
+    assert len(deployment_view.relationship_views) == 1
+
+
 def test_add_animation_step_raises_if_no_elements(empty_workspace: Workspace):
     """Check error handling if no elements passed."""
     deployment_view = empty_workspace.views.create_deployment_view(