make compatible with sqlalchemy

examples/sqlalchemy.py

@@ -0,0 +1,51 @@
+from typing import Optional
+
+from sqlalchemy import types
+from sqlalchemy.util import generic_repr
+from typeid import TypeID, from_uuid
+
+
+class TypeIDType(types.TypeDecorator):
+    """
+    A SQLAlchemy TypeDecorator that allows storing TypeIDs in the database.
+    The prefix will not be persisted, instead the database-native UUID field will be used.
+    At retrieval time a TypeID will be constructed based on the configured prefix and the
+    UUID value from the database.
+
+    Usage:
+        # will result in TypeIDs such as "user_01h45ytscbebyvny4gc8cr8ma2"
+        id = mapped_column(
+            TypeIDType("user"),
+            primary_key=True,
+            default=lambda: TypeID("user")
+        )
+    """
+    impl = types.Uuid
+
+    cache_ok = True
+
+    prefix: Optional[str]
+
+    def __init__(self, prefix: Optional[str], *args, **kwargs):
+        self.prefix = prefix
+        super().__init__(*args, **kwargs)
+
+    def __repr__(self) -> str:
+        # Customize __repr__ to ensure that auto-generated code e.g. from alembic includes
+        # the right __init__ params (otherwise by default prefix will be omitted because
+        # uuid.__init__ does not have such an argument).
+        return generic_repr(
+            self,
+            to_inspect=TypeID(self.prefix),
+        )
+
+    def process_bind_param(self, value: TypeID, dialect):
+        if self.prefix is None:
+            assert value.prefix is None
+        else:
+            assert value.prefix == self.prefix
+
+        return value.uuid
+
+    def process_result_value(self, value, dialect):
+        return from_uuid(value, self.prefix)

tests/test_typeid.py

@@ -81,3 +81,15 @@ def test_construct_type_from_uuid_with_prefix() -> None:
     assert isinstance(typeid, TypeID)
     assert typeid.prefix == "prefix"
     assert isinstance(typeid.suffix, str)
+
+
+def test_hash_type_id() -> None:
+    prefix = "plov"
+    suffix = "00041061050r3gg28a1c60t3gf"
+
+    typeid_1 = TypeID(prefix=prefix, suffix=suffix)
+    typeid_2 = TypeID(prefix=prefix, suffix=suffix)
+    typeid_3 = TypeID(suffix=suffix)
+
+    assert hash(typeid_1) == hash(typeid_2)
+    assert hash(typeid_3) != hash(typeid_1)

typeid/typeid.py

@@ -26,6 +26,10 @@ def suffix(self) -> str:
     def prefix(self) -> str:
         return self._prefix
 
+    @property
+    def uuid(self) -> UUID:
+        return _convert_b32_to_uuid(self.suffix)
+
     def __str__(self) -> str:
         value = ""
         if self.prefix:
@@ -38,6 +42,9 @@ def __eq__(self, value: object) -> bool:
             return False
         return value.prefix == self.prefix and value.suffix == self.suffix
 
+    def __hash__(self) -> int:
+        return hash((self.prefix, self.suffix))
+
 
 def from_string(string: str) -> TypeID:
     prefix, suffix = get_prefix_and_suffix(string=string)
@@ -66,3 +73,7 @@ def get_prefix_and_suffix(string: str) -> tuple:
 
 def _convert_uuid_to_b32(uuid_instance: UUID) -> str:
     return base32.encode(list(uuid_instance.bytes))
+
+
+def _convert_b32_to_uuid(b32: str) -> UUID:
+    return UUID(bytes=bytes(base32.decode(b32)))