Fix: deleting models that depend on external nodes (#8330) (#8381)

(cherry picked from commit 34e6edb)

Co-authored-by: Michelle Ark <MichelleArk@users.noreply.github.com>
Co-authored-by: Jeremy Cohen <jeremy@dbtlabs.com>

.changes/unreleased/Fixes-20230811-212008.yaml

@@ -0,0 +1,7 @@
+kind: Fixes
+body: 'Fix: DbtInternalError after model that previously ref''d external model is
+  deleted'
+time: 2023-08-11T21:20:08.145554-04:00
+custom:
+  Author: michelleark
+  Issue: "8375"

core/dbt/parser/manifest.py

@@ -122,7 +122,7 @@
 from dbt.version import __version__
 
 from dbt.dataclass_schema import StrEnum, dbtClassMixin
-from dbt.plugins import get_plugin_manager
+from dbt import plugins
 
 from dbt_semantic_interfaces.enum_extension import assert_values_exhausted
 from dbt_semantic_interfaces.type_enums import MetricType
@@ -503,6 +503,7 @@ def load(self):
             self.manifest.selectors = self.root_project.manifest_selectors
 
             # inject any available external nodes
+            self.manifest.build_parent_and_child_maps()
             external_nodes_modified = self.inject_external_nodes()
             if external_nodes_modified:
                 self.manifest.rebuild_ref_lookup()
@@ -751,7 +752,7 @@ def inject_external_nodes(self) -> bool:
             manifest_nodes_modified = True
 
         # Inject any newly-available external nodes
-        pm = get_plugin_manager(self.root_project.project_name)
+        pm = plugins.get_plugin_manager(self.root_project.project_name)
         plugin_model_nodes = pm.get_nodes().models
         for node_arg in plugin_model_nodes.values():
             node = ModelNode.from_args(node_arg)

tests/functional/partial_parsing/test_partial_parsing.py

@@ -1,4 +1,5 @@
 import pytest
+from unittest import mock
 
 from dbt.tests.util import run_dbt, get_manifest, write_file, rm_file, run_dbt_and_capture
 from dbt.tests.fixtures.project import write_project_files
@@ -74,6 +75,7 @@
 from dbt.exceptions import CompilationError, ParsingError, DuplicateVersionedUnversionedError
 from dbt.contracts.files import ParseFileType
 from dbt.contracts.results import TestStatus
+from dbt.plugins.manifest import PluginNodes, ModelNodeArgs
 
 import re
 import os
@@ -805,3 +807,73 @@ def test_pp_groups(self, project):
         )
         with pytest.raises(ParsingError):
             results = run_dbt(["--partial-parse", "run"])
+
+
+class TestExternalModels:
+    @pytest.fixture(scope="class")
+    def external_model_node(self):
+        return ModelNodeArgs(
+            name="external_model",
+            package_name="external",
+            identifier="test_identifier",
+            schema="test_schema",
+        )
+
+    @pytest.fixture(scope="class")
+    def external_model_node_versioned(self):
+        return ModelNodeArgs(
+            name="external_model_versioned",
+            package_name="external",
+            identifier="test_identifier_v1",
+            schema="test_schema",
+            version=1,
+        )
+
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {"model_one.sql": model_one_sql}
+
+    @mock.patch("dbt.plugins.get_plugin_manager")
+    def test_pp_external_models(
+        self, get_plugin_manager, project, external_model_node, external_model_node_versioned
+    ):
+        # initial plugin - one external model
+        external_nodes = PluginNodes()
+        external_nodes.add_model(external_model_node)
+        get_plugin_manager.return_value.get_nodes.return_value = external_nodes
+
+        # initial run
+        manifest = run_dbt(["parse"])
+        assert len(manifest.nodes) == 2
+        assert set(manifest.nodes.keys()) == {
+            "model.external.external_model",
+            "model.test.model_one",
+        }
+        assert len(manifest.external_node_unique_ids) == 1
+        assert manifest.external_node_unique_ids == ["model.external.external_model"]
+
+        # add a model file
+        write_file(model_two_sql, project.project_root, "models", "model_two.sql")
+        manifest = run_dbt(["--partial-parse", "parse"])
+        assert len(manifest.nodes) == 3
+
+        # add an external model
+        external_nodes.add_model(external_model_node_versioned)
+        manifest = run_dbt(["--partial-parse", "parse"])
+        assert len(manifest.nodes) == 4
+        assert len(manifest.external_node_unique_ids) == 2
+
+        # add a model file that depends on external model
+        write_file(
+            "SELECT * FROM {{ref('external', 'external_model')}}",
+            project.project_root,
+            "models",
+            "model_depends_on_external.sql",
+        )
+        manifest = run_dbt(["--partial-parse", "parse"])
+        assert len(manifest.nodes) == 5
+
+        # remove a model file that depends on external model
+        rm_file(project.project_root, "models", "model_depends_on_external.sql")
+        manifest = run_dbt(["--partial-parse", "parse"])
+        assert len(manifest.nodes) == 4