rename key

layercake/layercake/dateutils.py

@@ -3,7 +3,6 @@ from datetime import datetime, timedelta
 
 import pytz
 
-
 TZ = os.getenv('TZ', 'UTC')
 
 

layercake/layercake/dynamodb.py

@@ -135,8 +135,8 @@ if TYPE_CHECKING:
     @dataclass
     class SortKey(str):
         """
-        SortKey encapsulates the sort key value and optionally stores additional attributes
-        for nested data extraction.
+        SortKey encapsulates the sort key value and optionally stores additional
+        attributes for nested data extraction.
 
         Parameters
         ----------
@@ -146,21 +146,18 @@ if TYPE_CHECKING:
             Optional specification for nested data extraction.
         remove_prefix: str, optional
             Optional prefix to remove from the key when forming the result dict.
-        retain_key: bool, optional
-            Use the key itself as value if True; otherwise, use the extracted value.
         """
 
         sk: str
         path_spec: str | None = None
         remove_prefix: str | None = None
-        retain_key: bool = False
 
 else:
 
     class SortKey(str):
         """
-        SortKey encapsulates the sort key value and optionally stores additional attributes
-        for nested data extraction.
+        SortKey encapsulates the sort key value and optionally stores additional
+        attributes for nested data extraction.
 
         Parameters
         ----------
@@ -170,8 +167,6 @@ else:
             Optional specification for nested data extraction.
         remove_prefix: str, optional
             Optional prefix to remove from the key when forming the result dict.
-        retain_key: bool, optional
-            Use the key itself as value if True; otherwise, use the extracted value.
         """
 
         def __new__(
@@ -180,7 +175,6 @@ else:
             *,
             path_spec: str | None = None,
             remove_prefix: str | None = None,
-            retain_key: bool = False,
         ) -> str:
             return super().__new__(cls, sk)
 
@@ -190,14 +184,12 @@ else:
             *,
             path_spec: str | None = None,
             remove_prefix: str | None = None,
-            retain_key: bool = False,
         ) -> None:
             # __init__ is used to store the parameters for later reference.
             # For immutable types like str, __init__ cannot change the instance's value.
             self.sk = sk
             self.path_spec = path_spec
             self.remove_prefix = remove_prefix
-            self.retain_key = retain_key
 
 
 class Key(ABC, dict):
@@ -228,11 +220,43 @@ class PartitionKey(Key):
 class KeyPair(Key):
     """Represents a composite key (partition key and sort key) for DynamoDB queries"""
 
-    def __init__(self, pk: str, sk: str) -> None:
+    def __init__(
+        self,
+        pk: str,
+        sk: str,
+        *,
+        rename_key: str | None = None,
+        retain_key: bool = False,
+    ) -> None:
+        """
+        Initializes a composite key using partition and sort key.
+
+        Parameters
+        ----------
+        pk : str
+            The partition key.
+        sk : str
+            The sort key.
+        rename_key : str, optional
+            If provided, renames the sort key in the output.
+        retain_key : bool, optional
+            Use the key itself as value if True; otherwise, use the extracted value.
+        """
+
         super().__init__(**{PK: pk, SK: sk})
+        self._rename_key = rename_key
+        self._retain_key = retain_key
+
+    @property
+    def rename_key(self) -> str | None:
+        return self._rename_key
+
+    @property
+    def retain_key(self) -> bool:
+        return self._retain_key
 
     def __repr__(self) -> str:
-        pk, sk = self.values()
+        pk, sk, *_ = self.values()
         return f'KeyPair({pk!r}, {sk!r})'
 
     def expr_attr_name(self) -> dict:
@@ -517,15 +541,19 @@ class DynamoDBPersistenceLayer:
         limit: int | None = None,
         index_forward: bool = True,
     ) -> dict[str, Any]:
-        """You must provide the name of the partition key attribute and a single value for that attribute.
+        """You must provide the name of the partition key attribute
+        and a single value for that attribute.
 
         Query returns all items with that partition key value.
-        Optionally, you can provide a sort key attribute and use a comparison operator to refine the search results.
+        Optionally, you can provide a sort key attribute and use a comparison operator
+        to refine the search results.
 
         ...
 
-        A `Query` operation always returns a result set. If no matching items are found, the result set will be empty.
-        Queries that do not return results consume the minimum number of read capacity units for that type of read operation.
+        A `Query` operation always returns a result set. If no matching items are found,
+        the result set will be empty.
+        Queries that do not return results consume the minimum number
+        of read capacity units for that type of read operation.
 
         - https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/dynamodb/client/query.html
         """
@@ -563,8 +591,11 @@ class DynamoDBPersistenceLayer:
             )
 
     def get_item(self, key: dict) -> dict:
-        """The GetItem operation returns a set of attributes for the item with the given primary key.
-        If there is no matching item, GetItem does not return any data and there will be no Item element in the response.
+        """The GetItem operation returns a set of attributes for the item
+        with the given primary key.
+
+        If there is no matching item, GetItem does not return any data and
+        there will be no Item element in the response.
         """
         attrs = {
             'TableName': self.table_name,
@@ -639,8 +670,9 @@ class DynamoDBPersistenceLayer:
         expr_attr_names: dict | None = None,
         expr_attr_values: dict | None = None,
     ) -> bool:
-        """Deletes a single item in a table by primary key. You can perform a conditional delete operation that deletes
-        the item if it exists, or if it has an expected attribute value.
+        """Deletes a single item in a table by primary key. You can perform
+        a conditional delete operation that deletes the item if it exists,
+        or if it has an expected attribute value.
         """
         attrs: dict = {
             'TableName': self.table_name,
@@ -722,15 +754,18 @@ class PaginatedResult(TypedDict):
 
 class DynamoDBCollection:
     """
-    DynamoDBCollection provides a high-level abstraction for performing common CRUD operations
-    and queries on a DynamoDB table. It leverages an underlying persistence layer to handle
-    serialization and deserialization of data, key composition, transaction operations, and TTL management.
+    DynamoDBCollection provides a high-level abstraction for performing common
+    CRUD operations and queries on a DynamoDB table.
+    It leverages an underlying persistence layer to handle
+    serialization and deserialization of data, key composition, transaction operations,
+    and TTL management.
 
     This collection class simplifies interaction with DynamoDB items, allowing users to:
         - Retrieve a single item or multiple items via transactions.
         - Insert (put) items with optional TTL (time-to-live) settings.
         - Delete items based on keys and conditions.
-        - Query items using partition keys or composite key pairs with optional filtering and pagination.
+        - Query items using partition keys or composite key pairs with
+        optional filtering and pagination.
 
     Parameters
     ----------
@@ -756,7 +791,6 @@ class DynamoDBCollection:
     def get_item(
         self,
         key: Key,
-        path_spec: str | None = None,
         /,
         raise_on_error: bool = True,
         exc_cls: Type[Exception] | None = None,
@@ -780,8 +814,6 @@ class DynamoDBCollection:
         ----------
         key: Key
             Key of the item to be retrieved.
-        path_spec: str, optional
-            A path specification for nested data extraction.
         raise_on_error: bool, optional
             If True, raises an exception when the item is not found.
         exc_cls: Type[Exception], optional
@@ -797,10 +829,12 @@ class DynamoDBCollection:
         Raises
         ------
         Exception
-            Raises the provided exception if the item is not found and raise_on_error is True.
+            Raises the provided exception if the item is not found
+            and raise_on_error is True.
         """
         exc_cls = exc_cls or self.exc_cls
         data = self.persistence_layer.get_item(key)
+        path_spec = getattr(key[SK], 'path_spec', None)
 
         if raise_on_error and not data:
             raise exc_cls(f'Item with {key} not found.')
@@ -826,7 +860,8 @@ class DynamoDBCollection:
         key: Key
             Key for the item to be inserted or updated.
         ttl: int or datetime, optional
-            Time-to-live for the item, specified as a timestamp integer or datetime object.
+            Time-to-live for the item, specified as a timestamp integer
+            or datetime object.
         **kwargs
             Additional data to be stored with the item.
 
@@ -836,18 +871,10 @@ class DynamoDBCollection:
             True if the operation is successful, False otherwise.
         """
         if isinstance(ttl, int):
-            kwargs.update(
-                {
-                    'ttl': ttl,
-                }
-            )
+            kwargs.update({'ttl': ttl})
 
         if isinstance(ttl, datetime):
-            kwargs.update(
-                {
-                    'ttl': timestamp(ttl),
-                }
-            )
+            kwargs.update({'ttl': timestamp(ttl)})
 
         return self.persistence_layer.put_item(item=key | kwargs)
 
@@ -897,20 +924,42 @@ class DynamoDBCollection:
 
             key = (
                 TransactKey('b3511b5a-cb32-4833-a373-f8223f2088d4')
-                + SortKey('sk-1') + SortKey('sk-2')
+                + SortKey('sk-1')
+                + SortKey('sk-2')
+            )
+            collect = DynamoDBCollection(...)
+            items = collect.get_items(key)
+
+        **Get items using chained key pairs**
+
+            key = (
+                KeyPair('b3511b5a-cb32-4833-a373-f8223f2088d4', '0')
+                + KeyPair('cpf', '07879819908')
+                + KeyPair('email', 'user@example.com')
             )
             collect = DynamoDBCollection(...)
             items = collect.get_items(key)
 
         Parameters
         ----------
-        key: TransactKey
-            A TransactKey instance that contains a partition key and one or more sort keys.
-            If no sort key is provided, the transaction is skipped.
+        key: TransactKey or KeyChain
+            A `TransactKey` is used when you want to define a partition key (`pk`)
+            and append multiple `SortKey` instances using the `+` operator. Each
+            `SortKey` is internally paired with the `pk` to form a `KeyPair`.
+
+            Alternatively, a `KeyChain` can be created by chaining two or more `KeyPair`
+            instances using the `+` operator. For example:
+            `KeyPair(pk1, sk1) + KeyPair(pk2, sk2)` creates a `KeyChain` with two pairs.
+            Further additions to the chain extend it.
+
+            If no sort keys (in `TransactKey`) or no key pairs (in `KeyChain`)
+            are provided, the operation is skipped.
 
         flatten_top: bool, optional
-            Determines whether the first nested item in the transaction result should be flattened,
-            i.e., extracted to serve as the primary item at the top level of the returned dict.
+            Determines whether the first nested item in the transaction result
+            should be flattened,
+            i.e., extracted to serve as the primary item at the top level of
+            the returned dict.
             If True, the nested item is promoted to the top level.
 
         Returns
@@ -949,21 +998,22 @@ class DynamoDBCollection:
                 return glom(obj, path_spec)
             return obj
 
-        def _removeprefix(pair: KeyPair) -> str:
+        def _mapkey(pair: KeyPair) -> str:
             pk = pair[PK]
             sk = pair[SK]
 
+            if pair.rename_key:
+                return pair.rename_key
+
             if not isinstance(sk, SortKey):
                 return pk
 
-            key = pk if sk.retain_key else sk
+            key = pk if pair.retain_key else sk
 
             return key.removeprefix(sk.remove_prefix or '')
 
         return head | {
-            _removeprefix(pair): _getin(pair, obj)
-            for pair, obj in zip(sortkeys, tail)
-            if obj
+            _mapkey(pair): _getin(pair, obj) for pair, obj in zip(sortkeys, tail) if obj
         }
 
     def query(
@@ -1044,6 +1094,11 @@ class DynamoDBCollection:
             _startkey_b64encode(response['last_key']) if response['last_key'] else None
         )
 
+        def _removeprefix(
+            items: list[dict[str, Any]], /, key: str, prefix: str
+        ) -> list[dict[str, Any]]:
+            return [x | {key: x[key].removeprefix(prefix)} for x in items]
+
         match key.get(PK), key.get(SK):
             case ComposeKey(), _:  # Remove prefix from Partition Key
                 items = _removeprefix(items, PK, key[PK].prefix + key[PK].delimiter)
@@ -1056,16 +1111,6 @@ class DynamoDBCollection:
         }
 
 
-def _removeprefix(
-    items: list[dict[str, Any]],
-    /,
-    key: str,
-    prefix: str,
-) -> list[dict[str, Any]]:
-    """Remove the given prefix from the value associated with key in each item."""
-    return [x | {key: x[key].removeprefix(prefix)} for x in items]
-
-
 def _startkey_b64encode(obj: dict) -> str:
     s = json.dumps(obj)
     b = urlsafe_b64encode(s.encode('utf-8')).decode('utf-8')

layercake/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "layercake"
-version = "0.3.1"
+version = "0.3.3"
 description = "Packages shared dependencies to optimize deployment and ensure consistency across functions."
 readme = "README.md"
 authors = [

layercake/tests/test_dynamodb.py

@@ -166,9 +166,11 @@ def test_collection_get_item_path_spec(
     data = collect.get_item(
         KeyPair(
             pk='5OxmMjL-ujoR5IMGegQz',
-            sk=ComposeKey('sergio@somosbeta.com.br', prefix='emails'),
+            sk=SortKey(
+                ComposeKey('sergio@somosbeta.com.br', prefix='emails'),
+                path_spec='mx_record_exists',
+            ),
         ),
-        'mx_record_exists',
         default={},
     )
     assert data
@@ -287,6 +289,20 @@ def test_collection_get_items(
     }
 
 
+def test_collection_get_items_not_found(
+    dynamodb_seeds,
+    dynamodb_persistence_layer: DynamoDBPersistenceLayer,
+):
+    collect = DynamoDBCollection(dynamodb_persistence_layer)
+    doc = collect.get_items(
+        TransactKey('not_found')
+        + SortKey('0')
+        + SortKey('metadata#not_found', path_spec='payment_method')
+    )
+
+    assert doc == {}
+
+
 def test_collection_get_items_unflatten(
     dynamodb_seeds,
     dynamodb_persistence_layer: DynamoDBPersistenceLayer,
@@ -378,15 +394,20 @@ def test_collection_get_items_pair_path_spec(
 ):
     collect = DynamoDBCollection(dynamodb_persistence_layer)
     doc = collect.get_items(
-        KeyPair('cpf', SortKey('07879819908', path_spec='user_id', retain_key=True))
+        KeyPair(
+            'cpf',
+            SortKey('07879819908', path_spec='user_id'),
+            rename_key='user_id',
+        )
         + KeyPair(
             'email',
-            SortKey('osergiosiqueira@gmail.com', path_spec='user_id', retain_key=True),
+            SortKey('osergiosiqueira@gmail.com', path_spec='user_id'),
+            retain_key=True,
         ),
         flatten_top=False,
     )
 
     assert doc == {
-        'cpf': '5OxmMjL-ujoR5IMGegQz',
+        'user_id': '5OxmMjL-ujoR5IMGegQz',
         'email': '5OxmMjL-ujoR5IMGegQz',
     }

layercake/uv.lock

@@ -589,7 +589,7 @@ wheels = [
 
 [[package]]
 name = "layercake"
-version = "0.3.0"
+version = "0.3.2"
 source = { editable = "." }
 dependencies = [
     { name = "arnparse" },