added return_fields function, attempting to optionally limit fields returned by find

Author: savynorem

aredis_om/model/model.py

@@ -421,6 +421,7 @@ def __init__(
         limit: Optional[int] = None,
         page_size: int = DEFAULT_PAGE_SIZE,
         sort_fields: Optional[List[str]] = None,
+        return_fields: Optional[List[str]] = None,
         nocontent: bool = False,
     ):
         if not has_redisearch(model.db()):
@@ -445,6 +446,11 @@ def __init__(
         else:
             self.sort_fields = []
 
+        if return_fields:
+            self.return_fields = self.validate_return_fields(return_fields)
+        else:
+            self.return_fields = []
+
         self._expression = None
         self._query: Optional[str] = None
         self._pagination: List[str] = []
@@ -502,8 +508,19 @@ def query(self):
                 if self._query.startswith("(") or self._query == "*"
                 else f"({self._query})"
             ) + f"=>[{self.knn}]"
+        if self.return_fields:
+            self._query += f" RETURN {','.join(self.return_fields)}"
         return self._query
 
+    def validate_return_fields(self, return_fields: List[str]):
+        for field in return_fields:
+            if field not in self.model.__fields__:  # type: ignore
+                raise QueryNotSupportedError(
+                    f"You tried to return the field {field}, but that field "
+                    f"does not exist on the model {self.model}"
+                )
+        return return_fields
+
     @property
     def query_params(self):
         params: List[Union[str, bytes]] = []
@@ -956,6 +973,11 @@ def sort_by(self, *fields: str):
         if not fields:
             return self
         return self.copy(sort_fields=list(fields))
+    
+    def return_fields(self, *fields: str):
+        if not fields:
+            return self
+        return self.copy(return_fields=list(fields))
 
     async def update(self, use_transaction=True, **field_values):
         """
@@ -1531,7 +1553,9 @@ def find(
         *expressions: Union[Any, Expression],
         knn: Optional[KNNExpression] = None,
     ) -> FindQuery:
-        return FindQuery(expressions=expressions, knn=knn, model=cls)
+        return FindQuery(
+            expressions=expressions, knn=knn, model=cls
+        )
 
     @classmethod
     def from_redis(cls, res: Any):

tests/test_json_model.py

@@ -935,9 +935,21 @@ class TypeWithUuid(JsonModel):
 
     await item.save()
 
+@py_test_mark_asyncio
+async def test_return_specified_fields(members, m):
+    member1, member2, member3 = members
+    actual = await m.Member.find(
+        (m.Member.first_name == "Andrew") & (m.Member.last_name == "Brookins")
+        | (m.Member.last_name == "Smith")
+    ).all()
+    assert actual == [
+        {"first_name": "Andrew", "last_name": "Brookins"},
+        {"first_name": "Andrew", "last_name": "Smith"},
+    ]
+
 
 @py_test_mark_asyncio
-async def test_xfix_queries(m):
+async def test_xfix_queries(m):4
     await m.Member(
         first_name="Steve",
         last_name="Lorello",