utils

create_base_metadata(base_obj=None, engine=None)

Create Base object's metadata.

Import this function early in your app/script (i.e. main.py) and run as soon as possible, i.e. after imports.

This function accepts a SQLAlchemy DeclarativeBase object, and creates the table metadata from that object using the Engine passed.

This function will only ever return True if successful. It does not return False, as an Exception is raised if metadata creation fails and the program is halted.

Parameters:

Name	Type	Description	Default
base_obj	DeclarativeBase	A SQLAlchemy DeclarativeBase object to extract metadata from	None
engine	Engine	The Engine to use for the database connection.	None

Raises

(ValueError): When input values are invalid
(OperationalError): When SQLAlchemy runs into an error with the database, usually starting
    on the database (not in SQLAlchemy)
(DBAPIERROR): When SQLAlchemy runs into an issue, generally in the way you've coded a SQLAlchemy
    statement or operation
(Exception): When an uncaught/unhandled exception occurs

Returns

(bool): `True` if creating `Base` metadata is successful

Source code in src/red_utils/ext/sqlalchemy_utils/utils.py

def create_base_metadata(
    base_obj: sa_orm.DeclarativeBase = None, engine: sa.Engine = None
) -> bool:
    """Create `Base` object's metadata.

    Import this function early in your app/script (i.e. `main.py`) and run as soon as
    possible, i.e. after imports.

    This function accepts a SQLAlchemy `DeclarativeBase` object, and creates the table
    metadata from that object using the `Engine` passed.

    This function will only ever return `True` if successful. It does not return `False`,
    as an `Exception` is raised if metadata creation fails and the program is halted.

    Params:
        base_obj (sqlalchemy.DeclarativeBase): A SQLAlchemy `DeclarativeBase` object to extract metadata from
        engine (sqlalchemy.Engine): The `Engine` to use for the database connection.

    Raises
    ------
        (ValueError): When input values are invalid
        (OperationalError): When SQLAlchemy runs into an error with the database, usually starting
            on the database (not in SQLAlchemy)
        (DBAPIERROR): When SQLAlchemy runs into an issue, generally in the way you've coded a SQLAlchemy
            statement or operation
        (Exception): When an uncaught/unhandled exception occurs

    Returns
    -------
        (bool): `True` if creating `Base` metadata is successful
    """
    try:
        base_obj.metadata.create_all(bind=engine)

        return True
    except OperationalError as op_exc:
        raise op_exc
    except DBAPIError as dbapi_exc:
        raise dbapi_exc
    except Exception as exc:
        raise Exception(f"Unhandled exception creating Base metadata. Details: {exc}")

debug_metadata_obj(metadata_obj=None)

Debug-print a SQLAlchemy MetaData object.

Loop over tables and print names.

Parameters:

Name	Type	Description	Default
metadata_obj	MetaData	A SQLAlchemy MetaData object to debug	None

Source code in src/red_utils/ext/sqlalchemy_utils/utils.py

def debug_metadata_obj(metadata_obj: sa.MetaData = None) -> None:
    """Debug-print a SQLAlchemy MetaData object.

    Loop over tables and print names.

    Params:
        metadata_obj (sqlalchemy.MetaData): A SQLAlchemy `MetaData` object to debug
    """
    if not metadata_obj:
        raise ValueError("Missing a SQLAlchemy metadata object.")

    if not isinstance(metadata_obj, sa.MetaData):
        raise ValueError(
            f"Expected a MetaData obj, not object of type '{type(metadata_obj).__name__}'"
        )

    for _table in metadata_obj.sorted_tables:
        print(f"Table name: {_table.name}")

generate_metadata(metadata_obj=None, engine=None)

Create SQLAlchemy table metadata.

Accept a SQLalchemy MetaData object, run .create_all(engine) to create table metadata.

Raises

(ValueError): When input values are invalid
(OperationalError): When SQLAlchemy runs into an error with the database, usually starting
    on the database (not in SQLAlchemy)
(DBAPIERROR): When SQLAlchemy runs into an issue, generally in the way you've coded a SQLAlchemy
    statement or operation
(Exception): When an uncaught/unhandled exception occurs

Parameters:

Name	Type	Description	Default
metadata_obj	MetaData	A SQLAlchemy MetaData object to use for generating in the database	None
engine	Engine	The SQLAlchemy Engine to use for the database connection	None

Source code in src/red_utils/ext/sqlalchemy_utils/utils.py

def generate_metadata(
    metadata_obj: sa.MetaData = None, engine: sa.Engine = None
) -> None:
    """Create SQLAlchemy table metadata.

    Accept a SQLalchemy MetaData object, run .create_all(engine) to create
    table metadata.

    Raises
    ------
        (ValueError): When input values are invalid
        (OperationalError): When SQLAlchemy runs into an error with the database, usually starting
            on the database (not in SQLAlchemy)
        (DBAPIERROR): When SQLAlchemy runs into an issue, generally in the way you've coded a SQLAlchemy
            statement or operation
        (Exception): When an uncaught/unhandled exception occurs

    Params:
        metadata_obj (sqlalchemy.MetaData): A SQLAlchemy `MetaData` object to use for generating in the database
        engine (sqlalchemy.Engine): The SQLAlchemy `Engine` to use for the database connection
    """
    if not metadata_obj:
        raise ValueError("Missing a SQLAlchemy MetaData object.")

    if not isinstance(metadata_obj, sa.MetaData):
        raise ValueError(
            f"Expected a MetaData obj, not object of type '{type(metadata_obj).__name__}'"
        )

    if not engine:
        raise ValueError("Missing a SQLAlchemy engine object.")

    if not isinstance(engine, sa.Engine):
        raise ValueError(
            f"Expected a SQLAlchemy engine obj, not object of type '{type(engine).__name__}"
        )

    try:
        metadata_obj.create_all(engine)

        return True
    except OperationalError as op_exc:
        raise op_exc
    except DBAPIError as dbapi_exc:
        raise dbapi_exc
    except Exception as exc:
        raise Exception(f"Unhandled exception creating Base metadata. Details: {exc}")

get_engine(connection=None, db_type='sqlite', echo=False, pool_pre_ping=False)

Return a SQLAlchemy Engine object.

SQLAlchemy docs: Engine

To use a database other than SQLite, i.e. Postgres or MySQL, pass the lowercase string name of the database.

Currently supported databases

• [x] SQLite
• [x] Postgres
• [ ] MySQL
• [x] MSSQL
• [ ] Azure Cosmos

Parameters:

Name	Type	Description	Default
connection	(saSQLiteConnection, saPGConnection)	Instantiated instance of a custom database connection class	None
db_type	str	The string name (lowercase) of a database type	'sqlite'
echo	bool	If True, the SQL the Engine runs will be echoed to the CLI	False
pool_pre_ping	bool	Test connection pool before starting operations	False

Returns

(sqlalchemy.Engine): An initialized SQLAlchemy `Engine` object

Source code in src/red_utils/ext/sqlalchemy_utils/utils.py

def get_engine(
    connection: Union[saSQLiteConnection, saPGConnection, str] = None,
    db_type: str = "sqlite",
    echo: bool = False,
    pool_pre_ping: bool = False,
) -> sa.Engine:
    """Return a SQLAlchemy Engine object.

    [SQLAlchemy docs: Engine](https://docs.sqlalchemy.org/en/20/tutorial/engine.html)

    To use a database other than SQLite, i.e. Postgres or MySQL, pass
    the lowercase string name of the database.

    Currently supported databases:
        - [x] SQLite
        - [x] Postgres
        - [ ] MySQL
        - [x] MSSQL
        - [ ] Azure Cosmos

    Params:
        connection (saSQLiteConnection, saPGConnection): Instantiated instance of a custom database connection class
        db_type (str): The string name (lowercase) of a database type
        echo (bool): If `True`, the SQL the `Engine` runs will be echoed to the CLI
        pool_pre_ping (bool): Test connection pool before starting operations

    Returns
    -------
        (sqlalchemy.Engine): An initialized SQLAlchemy `Engine` object
    """
    if not connection:
        raise ValueError("Missing connection object/string.")

    if isinstance(connection, str):
        if db_type == "sqlite":
            connection: saSQLiteConnection = saSQLiteConnection(database=connection)

    ## Validate db_type input
    if db_type:
        _valid: bool = validate_db_type(db_type)

        if not _valid:
            raise ValueError(
                f"Invalid db_type: {db_type}. Must be one of: {valid_db_types}"
            )

    else:
        ## Default to sqlite if no db_type is passed
        db_type = "sqlite"

    if db_type == "sqlite":
        ## Ensure path to database file exists
        connection.ensure_path()

    if db_type == "postgres":
        pass

    if db_type == "mssql":
        pass

    try:
        engine = create_engine(
            connection.connection_string, echo=echo, pool_pre_ping=pool_pre_ping
        )

        return engine

    except OperationalError as op_exc:
        raise OperationalError(
            f"SQLAlchemy OperationalError exception occurred connecting to database {connection.database}. Details: {op_exc}"
        )

    except Exception as exc:
        raise Exception(f"Unhandled exception creating database engine. Details: {exc}")

get_session(engine=None, autoflush=False, expire_on_commit=False, class_=Session)

Define a factory for creating SQLAlchemy sessions.

Returns a sqlalchemy.orm.sessionmaker Session instance. Import this function in scripts that interact with the database, and create a SessionLocal object with SessionLocal = get_session(**args)

Parameters:

Name	Type	Description	Default
engine	Engine	A SQLAlchemy Engine object to use for connections	None
autoflush	bool	Automatically run flush operation on commits	False
expire_on_commit	bool	If True, connection expires once it's closed	False
class_		You can specify a class which should be returned instead of sqlalchemy.orm.Session. SQLAlchemy: sessionmaker class_ docs	Session

Returns

(sessionmaker[Session]): An initialized `Session` instance

Source code in src/red_utils/ext/sqlalchemy_utils/utils.py

def get_session(
    engine: sa.Engine = None,
    autoflush: bool = False,
    expire_on_commit: bool = False,
    class_=Session,
) -> sessionmaker[Session]:
    """Define a factory for creating SQLAlchemy sessions.

    Returns a `sqlalchemy.orm.sessionmaker` `Session` instance. Import this
    function in scripts that interact with the database, and create a
    `SessionLocal` object with `SessionLocal = get_session(**args)`

    Params:
        engine (sqlalchemy.Engine): A SQLAlchemy `Engine` object to use for connections
        autoflush (bool): Automatically run `flush` operation on commits
        expire_on_commit (bool): If `True`, connection expires once it's closed
        class_: You can specify a class which should be returned instead of `sqlalchemy.orm.Session`.
            [SQLAlchemy: sessionmaker class_ docs](https://docs.sqlalchemy.org/en/20/orm/session_api.html#sqlalchemy.orm.Session.params.class_)

    Returns
    -------
        (sessionmaker[Session]): An initialized `Session` instance
    """
    try:
        _sess = sessionmaker(
            bind=engine,
            autoflush=autoflush,
            expire_on_commit=expire_on_commit,
            class_=class_,
        )

        return _sess
    except Exception as exc:
        raise Exception(
            f"Unhandled exception creating a sessionmaker Session. Details: {exc}"
        )

validate_db_type(in_str=None)

Validate db_type string in functions that utilize db_type.

Parameters:

Name	Type	Description	Default
in_str	str	A db_type string to validate	None

Raises

(ValueError): Raises a `ValueError` if the `in_str` is not valid

Returns

(bool): `True` if `in_str` is valid

Source code in src/red_utils/ext/sqlalchemy_utils/utils.py

def validate_db_type(in_str: str = None) -> bool:
    """Validate `db_type` string in functions that utilize `db_type`.

    Params:
        in_str (str): A `db_type` string to validate

    Raises
    ------
        (ValueError): Raises a `ValueError` if the `in_str` is not valid

    Returns
    -------
        (bool): `True` if `in_str` is valid
    """
    if not in_str:
        raise ValueError("Missing input string to validate")

    if in_str not in valid_db_types:
        return False

    return True