Tweak snapshot config to allow using schema/database/alias macros

core/dbt/artifacts/resources/v1/snapshot.py

@@ -19,10 +19,9 @@ class SnapshotConfig(NodeConfig):
     check_cols: Union[str, List[str], None] = None
 
     def final_validate(self):
-        if not self.strategy or not self.unique_key or not self.target_schema:
+        if not self.strategy or not self.unique_key:
             raise ValidationError(
-                "Snapshots must be configured with a 'strategy', 'unique_key', "
-                "and 'target_schema'."
+                "Snapshots must be configured with a 'strategy' and 'unique_key'."
             )
         if self.strategy == "check":
             if not self.check_cols:

core/dbt/parser/base.py

@@ -72,6 +72,7 @@ def __init__(
 
 
 class RelationUpdate:
+    # "component" is database, schema or alias
     def __init__(self, config: RuntimeConfig, manifest: Manifest, component: str) -> None:
         default_macro = manifest.find_generate_macro_by_name(
             component=component,
@@ -127,6 +128,7 @@ def __init__(
     ) -> None:
         super().__init__(project, manifest, root_project)
 
+        # this sets callables from RelationUpdate
         self._update_node_database = RelationUpdate(
             manifest=manifest, config=root_project, component="database"
         )
@@ -288,13 +290,6 @@ def update_parsed_node_relation_names(
         self._update_node_schema(parsed_node, config_dict.get("schema"))
         self._update_node_alias(parsed_node, config_dict.get("alias"))
 
-        # Snapshot nodes use special "target_database" and "target_schema" fields for some reason
-        if getattr(parsed_node, "resource_type", None) == NodeType.Snapshot:
-            if "target_database" in config_dict and config_dict["target_database"]:
-                parsed_node.database = config_dict["target_database"]
-            if "target_schema" in config_dict and config_dict["target_schema"]:
-                parsed_node.schema = config_dict["target_schema"]
-
         self._update_node_relation_name(parsed_node)
 
     def update_parsed_node_config(

core/dbt/parser/snapshots.py

@@ -29,16 +29,22 @@ def set_snapshot_attributes(self, node):
         # `database` value of the node (ultimately sourced from the `database`
         # config value), and if that is not set, use the database defined in
         # the adapter's credentials.
+        changed = False
         if node.config.target_database:
             node.database = node.config.target_database
-        elif not node.database:
+            changed = True
+        elif not node.database:  # does this ever happen?
             node.database = self.root_project.credentials.database
+            changed = True
 
         # the target schema must be set if we got here, so overwrite the node's
         # schema
-        node.schema = node.config.target_schema
-        # We need to set relation_name again, since database/schema might have changed
-        self._update_node_relation_name(node)
+        if node.config.target_schema:
+            node.schema = node.config.target_schema
+            changed = True
+        if changed:
+            # We need to set relation_name again, since database/schema might have changed
+            self._update_node_relation_name(node)
 
         return node