Adding children in addition to parents (#113)

As discussed
[here](#111),
adding `children` to models / sources / snapshots. This is a simple
addition to the logic that populates parents; basically, if `x` is one
of `y`'s parents, then `y` is one of `x`'s children.

This allows writing rules like:
```
@rule(severity=Severity.CRITICAL)
def children_of_beta_models_should_be_beta_models(
    model: Model,
) -> RuleViolation | None:
    """Children of beta models should be beta models"""
    if "beta" in model.tags:
        for child in model.children:
            if "beta" not in child.tags:
                return RuleViolation(
                    message=f"Beta model {model.name} has a child that isn't a beta model {child.name}"
                )
    return None
```

This will need to be updated slightly for new evaluable types, but that
should be easy.

---------

Co-authored-by: Jochem van Dooren <[email protected]>

Author: ross-whatnot

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to
 ## [Unreleased]
 
 - Add support for linting and scoring dbt seeds (#110)
+- Add `children` to models, snapshots, and sources. (#113)
 - Add `parents` to models and snapshots, allowing access to parent nodes. (#109)
 
 ## [0.11.0] - 2025-04-04

src/dbt_score/models.py

@@ -6,7 +6,7 @@
 from collections import defaultdict
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Any, Iterable, List, Literal, TypeAlias, Union
+from typing import Any, Iterable, Literal, TypeAlias, Union
 
 from dbt_score.dbt_utils import dbt_ls
 
@@ -156,6 +156,7 @@ def _get_columns(
 
 # Type annotation for parent references
 ParentType = Union["Model", "Source", "Snapshot", "Seed"]
+ChildType = Union["Model", "Snapshot"]
 
 
 @dataclass
@@ -184,6 +185,7 @@ class Model(HasColumnsMixin):
         tests: The list of tests attached to the model.
         depends_on: Dictionary of models/sources/macros that the model depends on.
         parents: The list of models, sources, and snapshots this model depends on.
+        children: The list of models and snapshots that depend on this model.
         _raw_values: The raw values of the model (node) in the manifest.
         _raw_test_values: The raw test values of the model (node) in the manifest.
     """
@@ -209,7 +211,8 @@ class Model(HasColumnsMixin):
     tests: list[Test] = field(default_factory=list)
     depends_on: dict[str, list[str]] = field(default_factory=dict)
     constraints: list[Constraint] = field(default_factory=list)
-    parents: List[ParentType] = field(default_factory=list)
+    parents: list[ParentType] = field(default_factory=list)
+    children: list[ChildType] = field(default_factory=list)
     _raw_values: dict[str, Any] = field(default_factory=dict)
     _raw_test_values: list[dict[str, Any]] = field(default_factory=list)
 
@@ -319,6 +322,7 @@ class Source(HasColumnsMixin):
         patch_path: The yml path of the source definition.
         tags: The list of tags attached to the source table.
         tests: The list of tests attached to the source table.
+        children: The list of models and snapshots that depend on this source.
         _raw_values: The raw values of the source definition in the manifest.
         _raw_test_values: The raw test values of the source definition in the manifest.
     """
@@ -342,6 +346,7 @@ class Source(HasColumnsMixin):
     patch_path: str | None = None
     tags: list[str] = field(default_factory=list)
     tests: list[Test] = field(default_factory=list)
+    children: list[ChildType] = field(default_factory=list)
     _raw_values: dict[str, Any] = field(default_factory=dict)
     _raw_test_values: list[dict[str, Any]] = field(default_factory=list)
 
@@ -424,6 +429,7 @@ class Snapshot(HasColumnsMixin):
         strategy: The strategy of the snapshot.
         unique_key: The unique key of the snapshot.
         parents: The list of models, sources, and snapshots this snapshot depends on.
+        children: The list of models and snapshots that depend on this snapshot.
         _raw_values: The raw values of the snapshot (node) in the manifest.
         _raw_test_values: The raw test values of the snapshot (node) in the manifest.
     """
@@ -448,7 +454,8 @@ class Snapshot(HasColumnsMixin):
     depends_on: dict[str, list[str]] = field(default_factory=dict)
     strategy: str | None = None
     unique_key: list[str] | None = None
-    parents: List[ParentType] = field(default_factory=list)
+    parents: list[ParentType] = field(default_factory=list)
+    children: list[ChildType] = field(default_factory=list)
     _raw_values: dict[str, Any] = field(default_factory=dict)
     _raw_test_values: list[dict[str, Any]] = field(default_factory=list)
 
@@ -512,6 +519,7 @@ class Seed(HasColumnsMixin):
         patch_path: The yml path of the seed, e.g. `seeds.yml`.
         tags: The list of tags attached to the seed.
         tests: The list of tests attached to the seed.
+        children: The list of models and snapshots that depend on this seed.
         _raw_values: The raw values of the seed (node) in the manifest.
         _raw_test_values: The raw test values of the seed (node) in the manifest.
     """
@@ -531,6 +539,7 @@ class Seed(HasColumnsMixin):
     patch_path: str | None = None
     tags: list[str] = field(default_factory=list)
     tests: list[Test] = field(default_factory=list)
+    children: list[ChildType] = field(default_factory=list)
     _raw_values: dict[str, Any] = field(default_factory=dict)
     _raw_test_values: list[dict[str, Any]] = field(default_factory=list)
 
@@ -607,7 +616,7 @@ def __init__(self, file_path: Path, select: Iterable[str] | None = None):
         self._load_sources()
         self._load_snapshots()
         self._load_seeds()
-        self._populate_parents()
+        self._populate_relatives()
 
         if select:
             self._filter_evaluables(select)
@@ -661,18 +670,22 @@ def _reindex_tests(self) -> None:
                 ):
                     self.tests[node_unique_id].append(node_values)
 
-    def _populate_parents(self) -> None:
-        """Populate `parents` for all models and snapshots."""
+    def _populate_relatives(self) -> None:
+        """Populate `parents` and `children` for all evaluables."""
         for node in list(self.models.values()) + list(self.snapshots.values()):
             for parent_id in node.depends_on.get("nodes", []):
                 if parent_id in self.models:
                     node.parents.append(self.models[parent_id])
+                    self.models[parent_id].children.append(node)
                 elif parent_id in self.snapshots:
                     node.parents.append(self.snapshots[parent_id])
+                    self.snapshots[parent_id].children.append(node)
                 elif parent_id in self.sources:
                     node.parents.append(self.sources[parent_id])
+                    self.sources[parent_id].children.append(node)
                 elif parent_id in self.seeds:
                     node.parents.append(self.seeds[parent_id])
+                    self.seeds[parent_id].children.append(node)
 
     def _filter_evaluables(self, select: Iterable[str]) -> None:
         """Filter evaluables like dbt's --select."""

tests/resources/manifest.json

@@ -134,7 +134,9 @@
       "alias": "model2_alias",
       "patch_path": "/path/to/model2.yml",
       "tags": [],
-      "depends_on": {},
+      "depends_on": {
+        "nodes": ["seed.package.seed1"]
+      },
       "language": "sql",
       "access": "public",
       "group": "them_over_there"

tests/test_models.py

@@ -40,15 +40,30 @@ def test_manifest_load(mock_read_text, raw_manifest):
         assert loader.snapshots["snapshot.package.snapshot1"].parents == [
             loader.models["model.package.model1"]
         ]
+        assert loader.models["model.package.model1"].children == [
+            loader.snapshots["snapshot.package.snapshot1"]
+        ]
         assert loader.models["model.package.model1"].parents == [
             loader.models["model.package.model2"],
             loader.sources["source.package.my_source.table1"],
             loader.snapshots["snapshot.package.snapshot2"],
         ]
-        assert loader.models["model.package.model2"].parents == []
+        assert loader.models["model.package.model2"].children == [
+            loader.models["model.package.model1"]
+        ]
+        assert loader.models["model.package.model2"].parents == [
+            loader.seeds["seed.package.seed1"]
+        ]
         assert loader.snapshots["snapshot.package.snapshot2"].parents == [
             loader.sources["source.package.my_source.table1"]
         ]
+        assert loader.sources["source.package.my_source.table1"].children == [
+            loader.models["model.package.model1"],
+            loader.snapshots["snapshot.package.snapshot2"],
+        ]
+        assert loader.seeds["seed.package.seed1"].children == [
+            loader.models["model.package.model2"]
+        ]
 
 
 @patch("dbt_score.models.Path.read_text")