Switches JSON type from TEXT to JSONB.

Author: Daverball

HISTORY.rst

@@ -1,6 +1,18 @@
 Changelog
 ---------
 
+- Replaces `JSON` database type with `JSONB`, this means
+  Postgres as a backend is not required. You will also need
+  to write a migration for existing JSON columns. You may use
+  the following recipe using an alembic `Operations` object::
+
+    operations.alter_column(
+      'table_name',
+      'column_name',
+      type_=JSON,
+      postgresql_using='"column_name"::jsonb'
+    )
+
 0.8.0 (15.01.2025)
 ~~~~~~~~~~~~~~~~~~~
 

README.rst

@@ -2,8 +2,8 @@ Libres
 ======
 
 Libres is a reservations management library to reserve things like tables at
-a restaurant or tickets at an event. It works with Python 3.8+
-and requires Postgresql 9.1+.
+a restaurant or tickets at an event. It works with Python 3.9+
+and requires Postgresql 9.2+.
 
 `Documentation <http://libres.readthedocs.org/en/latest/>`_ | `Source <http://github.com/seantis/libres/>`_ | `Bugs <http://github.com/seantis/libres/issues>`_
 

src/libres/db/models/allocation.py

@@ -118,7 +118,7 @@ class Allocation(TimestampMixin, ORMBase, OtherModels):
     timezone: Column[str | None] = Column(types.String())
 
     #: Custom data reserved for the user
-    data: Column[Any | None] = Column(
+    data: Column[dict[str, Any] | None] = Column(
         JSON(),
         nullable=True
     )

src/libres/db/models/reservation.py

@@ -96,7 +96,7 @@ class Reservation(TimestampMixin, ORMBase, OtherModels):
         nullable=False
     )
 
-    data: Column[Any | None] = deferred(
+    data: Column[dict[str, Any] | None] = deferred(
         Column(
             JSON(),
             nullable=True

src/libres/db/models/types/json_type.py

@@ -1,49 +1,46 @@
 from __future__ import annotations
 
-from json import loads, dumps
-from sqlalchemy.types import TypeDecorator, TEXT
+from sqlalchemy.ext.mutable import MutableDict
+from sqlalchemy.types import TypeDecorator
+from sqlalchemy.dialects.postgresql import JSONB
 
 
 from typing import Any
 from typing import TYPE_CHECKING
 if TYPE_CHECKING:
     from sqlalchemy.engine import Dialect
 
-    _Base = TypeDecorator[Any]
+    _Base = TypeDecorator[dict[str, Any]]
 else:
     _Base = TypeDecorator
 
 
 class JSON(_Base):
-    """Like the default JSON, but using the json serializer from the dialect
-    (postgres) each time the value is read, even if it never left the ORM. The
-    default json type will only do it when the record is read from the
-    database.
+    """ A JSONB based type that coerces None's to empty dictionaries.
+
+    That is, this JSONB column cannot be `'null'::jsonb`. It could
+    still be `NULL` though, if it's nullable and never explicitly
+    set. But on the Python end you should always see a dictionary.
 
     """
 
-    # FIXME: We should switch to JSONB now, but we will need to
-    #        add a database migration to OneGov at the same time
-    impl = TEXT
+    impl = JSONB
 
-    def process_bind_param(
+    def process_bind_param(  # type:ignore[override]
         self,
-        value: Any,
+        value: dict[str, Any] | None,
         dialect: Dialect
-    ) -> str | None:
-
-        if value is not None:
-            value = (dialect._json_serializer or dumps)(value)  # type:ignore
+    ) -> dict[str, Any]:
 
-        return value  # type: ignore[no-any-return]
+        return {} if value is None else value
 
     def process_result_value(
         self,
-        value: str | None,
+        value: dict[str, Any] | None,
         dialect: Dialect
-    ) -> Any | None:
+    ) -> dict[str, Any]:
+
+        return {} if value is None else value
 
-        if value is not None:
-            value = (dialect._json_deserializer or loads)(value)  # type:ignore
 
-        return value
+MutableDict.associate_with(JSON)  # type:ignore[no-untyped-call]

tests/test_scheduler.py

@@ -1821,7 +1821,7 @@ def session_provider(context):
     scheduler.allocate((start, end), data=None)
     scheduler.commit()
 
-    assert scheduler.managed_allocations().first().data is None
+    assert scheduler.managed_allocations().first().data == {}
 
 
 def test_no_reservations_to_confirm(scheduler):