Relationship resolution!

crudkit/core/service.py

@@ -20,6 +20,12 @@ class CRUDService(Generic[T]):
             order_by = spec.parse_sort()
             limit, offset = spec.parse_pagination()
 
+            for parent, relationship_attr, alias in spec.get_join_paths():
+                query = query.join(alias, relationship_attr.of_type(alias), isouter=True)
+
+            for eager in spec.get_eager_loads():
+                query = query.options(eager)
+
             if filters:
                 query = query.filter(*filters)
             if order_by:

crudkit/core/spec.py

@@ -1,5 +1,7 @@
-from typing import List, Tuple
+from typing import List, Tuple, Set, Dict
-from sqlalchemy import asc, desc, or_, and_
+from sqlalchemy import asc, desc
+from sqlalchemy.orm import joinedload, aliased
+from sqlalchemy.orm.attributes import InstrumentedAttribute
 
 OPERATORS = {
     'eq': lambda col, val: col == val,
@@ -15,6 +17,34 @@ class CRUDSpec:
     def __init__(self, model, params):
         self.model = model
         self.params = params
+        self.eager_paths: Set[Tuple[str, ...]] = set()
+        self.join_paths: List[Tuple[object, InstrumentedAttribute, object]] = []
+        self.alias_map: Dict[Tuple[str, ...], object] = {}
+
+    def _resolve_column(self, path: str):
+        current_model = self.model
+        current_alias = self.model
+        parts = path.split('.')
+        join_path = []
+
+        for i, attr in enumerate(parts):
+            if not hasattr(current_model, attr):
+                return None, None
+            attr_obj = getattr(current_model, attr)
+            if isinstance(attr_obj, InstrumentedAttribute):
+                if hasattr(attr_obj.property, 'direction'):
+                    join_path.append(attr)
+                    path_key = tuple(join_path)
+                    alias = self.alias_map.get(path_key)
+                    if not alias:
+                        alias = aliased(attr_obj.property.mapper.class_)
+                        self.alias_map[path_key] = alias
+                        self.join_paths.append((current_alias, attr_obj, alias))
+                    current_model = attr_obj.property.mapper.class_
+                    current_alias = alias
+                else:
+                    return getattr(current_alias, attr), tuple(join_path) if join_path else None
+        return None, None
 
     def parse_filters(self):
         filters = []
@@ -22,12 +52,17 @@ class CRUDSpec:
             if key in ('sort', 'limit', 'offset'):
                 continue
             if '__' in key:
-                field, op = key.split('__', 1)
+                path_op = key.rsplit('__', 1)
+                if len(path_op) != 2:
+                    continue
+                path, op = path_op
             else:
-                field, op = key, 'eq'
+                path, op = key, 'eq'
-            if hasattr(self.model, field):
+            col, join_path = self._resolve_column(path)
-                col = getattr(self.model, field)
+            if col and op in OPERATORS:
                 filters.append(OPERATORS[op](col, value))
+                if join_path:
+                    self.eager_paths.add(join_path)
         return filters
 
     def parse_sort(self):
@@ -43,11 +78,33 @@ class CRUDSpec:
             else:
                 field = part
                 order = asc
-            if hasattr(self.model, field):
+            col, join_path = self._resolve_column(field)
-                result.append(order(getattr(self.model, field)))
+            if col:
+                result.append(order(col))
+                if join_path:
+                    self.eager_paths.add(join_path)
         return result
 
     def parse_pagination(self):
         limit = int(self.params.get('limit', 100))
         offset = int(self.params.get('offset', 0))
         return limit, offset
+
+    def get_eager_loads(self):
+        loads = []
+        for path in self.eager_paths:
+            current = self.model
+            loader = None
+            for attr in path:
+                attr_obj = getattr(current, attr)
+                if loader is None:
+                    loader = joinedload(attr_obj)
+                else:
+                    loader = loader.joinedload(attr_obj)
+                current = attr_obj.property.mapper.class_
+            if loader:
+                loads.append(loader)
+        return loads
+
+    def get_join_paths(self):
+        return self.join_paths