Support async DB driver: replace psycopg with asyncpg and adopt async Alembic template

backend/app/alembic/README

@@ -1 +1 @@
-Generic single-database configuration.
+Generic single-database configuration with an async dbapi.

backend/app/alembic/env.py

@@ -1,27 +1,30 @@
-import os
+import asyncio
 from logging.config import fileConfig
 
+from sqlalchemy import pool
+from sqlalchemy.engine import Connection
+from sqlalchemy.ext.asyncio import async_engine_from_config
+
 from alembic import context
-from sqlalchemy import engine_from_config, pool
+
+from app.models import SQLModel  # noqa
+from app.core.config import settings # noqa
 
 # this is the Alembic Config object, which provides
 # access to the values within the .ini file in use.
 config = context.config
+# Override the placeholder URL in alembic.ini with the value from settings.
+config.set_main_option("sqlalchemy.url", str(settings.SQLALCHEMY_DATABASE_URI))
 
 # Interpret the config file for Python logging.
 # This line sets up loggers basically.
-assert config.config_file_name is not None
-fileConfig(config.config_file_name)
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
 
 # add your model's MetaData object here
 # for 'autogenerate' support
 # from myapp import mymodel
 # target_metadata = mymodel.Base.metadata
-# target_metadata = None
-
-from app.models import SQLModel  # noqa
-from app.core.config import settings # noqa
-
 target_metadata = SQLModel.metadata
 
 # other values from the config, defined by the needs of env.py,
@@ -30,11 +33,7 @@
 # ... etc.
 
 
-def get_url():
-    return str(settings.SQLALCHEMY_DATABASE_URI)
-
-
-def run_migrations_offline():
+def run_migrations_offline() -> None:
     """Run migrations in 'offline' mode.
 
     This configures the context with just a URL
@@ -46,38 +45,47 @@ def run_migrations_offline():
     script output.
 
     """
-    url = get_url()
+    url = config.get_main_option("sqlalchemy.url")
     context.configure(
-        url=url, target_metadata=target_metadata, literal_binds=True, compare_type=True
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
     )
 
     with context.begin_transaction():
         context.run_migrations()
 
 
-def run_migrations_online():
-    """Run migrations in 'online' mode.
+def do_run_migrations(connection: Connection) -> None:
+    context.configure(connection=connection, target_metadata=target_metadata)
+
+    with context.begin_transaction():
+        context.run_migrations()
+
 
-    In this scenario we need to create an Engine
+async def run_async_migrations() -> None:
+    """In this scenario we need to create an Engine
     and associate a connection with the context.
 
     """
-    configuration = config.get_section(config.config_ini_section)
-    assert configuration is not None
-    configuration["sqlalchemy.url"] = get_url()
-    connectable = engine_from_config(
-        configuration,
+
+    connectable = async_engine_from_config(
+        config.get_section(config.config_ini_section, {}),
         prefix="sqlalchemy.",
         poolclass=pool.NullPool,
     )
 
-    with connectable.connect() as connection:
-        context.configure(
-            connection=connection, target_metadata=target_metadata, compare_type=True
-        )
+    async with connectable.connect() as connection:
+        await connection.run_sync(do_run_migrations)
+
+    await connectable.dispose()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode."""
 
-        with context.begin_transaction():
-            context.run_migrations()
+    asyncio.run(run_async_migrations())
 
 
 if context.is_offline_mode():

backend/app/alembic/script.py.mako

@@ -5,21 +5,24 @@ Revises: ${down_revision | comma,n}
 Create Date: ${create_date}
 
 """
+from typing import Sequence, Union
+
 from alembic import op
 import sqlalchemy as sa
-import sqlmodel.sql.sqltypes
 ${imports if imports else ""}
 
 # revision identifiers, used by Alembic.
-revision = ${repr(up_revision)}
-down_revision = ${repr(down_revision)}
-branch_labels = ${repr(branch_labels)}
-depends_on = ${repr(depends_on)}
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, Sequence[str], None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
 
 
-def upgrade():
+def upgrade() -> None:
+    """Upgrade schema."""
     ${upgrades if upgrades else "pass"}
 
 
-def downgrade():
+def downgrade() -> None:
+    """Downgrade schema."""
     ${downgrades if downgrades else "pass"}

backend/app/alembic/versions/cd5b3c3d1cd2_initialize_models.py

@@ -0,0 +1,56 @@
+"""initialize models
+
+Revision ID: cd5b3c3d1cd2
+Revises:
+Create Date: 2026-04-28 01:24:30.407103
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+import sqlmodel.sql.sqltypes
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'cd5b3c3d1cd2'
+down_revision: Union[str, Sequence[str], None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table(
+        'user',
+        sa.Column('email', sqlmodel.sql.sqltypes.AutoString(), nullable=False),
+        sa.Column('is_active', sa.Boolean(), nullable=False),
+        sa.Column('is_superuser', sa.Boolean(), nullable=False),
+        sa.Column('full_name', sqlmodel.sql.sqltypes.AutoString(), nullable=True),
+        sa.Column('id', sa.UUID(), nullable=False),
+        sa.Column('hashed_password', sqlmodel.sql.sqltypes.AutoString(), nullable=False),
+        sa.Column('created_at', sa.DateTime(timezone=True), nullable=True),
+        sa.PrimaryKeyConstraint('id'),
+    )
+    op.create_index(op.f('ix_user_email'), 'user', ['email'], unique=True)
+    op.create_table(
+        'item',
+        sa.Column('title', sqlmodel.sql.sqltypes.AutoString(), nullable=False),
+        sa.Column('description', sqlmodel.sql.sqltypes.AutoString(), nullable=True),
+        sa.Column('id', sa.UUID(), nullable=False),
+        sa.Column('created_at', sa.DateTime(timezone=True), nullable=True),
+        sa.Column('owner_id', sa.UUID(), nullable=False),
+        sa.ForeignKeyConstraint(['owner_id'], ['user.id'], ondelete='CASCADE'),
+        sa.PrimaryKeyConstraint('id'),
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('item')
+    op.drop_index(op.f('ix_user_email'), table_name='user')
+    op.drop_table('user')
+    # ### end Alembic commands ###