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SchemaMigrations

This class is responsible for managing the schema migrations in the database. It provides methods to create the schema_migrations table, check its existence, set the baseline version, and retrieve migration details.

Source code in pum/schema_migrations.py 
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class SchemaMigrations:
    """
    This class is responsible for managing the schema migrations in the database.
    It provides methods to create the schema_migrations table, check its existence,
    set the baseline version, and retrieve migration details.
    """

    def __init__(self, config: PumConfig):
        """
        Initialize the SchemaMigrations class with a database connection and configuration.

        Args:
            config (PumConfig): An instance of the PumConfig class containing configuration settings for the PUM system.
        """
        self.config = config

    def _pum_migrations_table_schema_name(self) -> Tuple[str, str]:
        """
        Returns the pum_migrations table name and schema
        """
        schema = "public"
        table = None
        table_identifiers = self.config.pum_migrations_table.split(".")
        if len(table_identifiers) > 2:
            raise ValueError(
                f"The pum_migrations_table '{self.config.pum_migrations_table}' must be in the format 'schema.table'"
            )
        elif len(table_identifiers) == 2:
            schema = table_identifiers[0]
            table = table_identifiers[1]
        else:
            table = table_identifiers[0]
        return schema, table

    def exists(self, conn: Connection):
        """
        Checks if the schema_migrations information table exists
        Args:
            conn (Connection): The database connection to check for the existence of the table.
        Returns:
            bool: True if the table exists, False otherwise."""

        schema, table = self._pum_migrations_table_schema_name()
        query = sql.SQL(
            """
        SELECT EXISTS (
            SELECT 1
            FROM information_schema.tables
            WHERE table_name = {table} AND table_schema = {schema}
        );
        """
        ).format(
            schema=sql.Literal(schema),
            table=sql.Literal(table),
        )

        cursor = execute_sql(conn, query)
        return cursor.fetchone()[0]

    def exists_in_other_schemas(self, conn: Connection) -> List[str]:
        """
        Checks if the schema_migrations information table exists in other schemas
        Args:
            conn (Connection): The database connection to check for the existence of the table.
        Returns:
            List[str]: List of schemas where the table exists.
        """
        schema, table = self._pum_migrations_table_schema_name()
        query = sql.SQL(
            """
            SELECT table_schema
            FROM information_schema.tables
            WHERE table_name = {table} AND table_schema != {schema}
        """
        ).format(
            schema=sql.Literal(schema),
            table=sql.Literal(table),
        )

        cursor = execute_sql(conn, query)
        return [row[0] for row in cursor.fetchall()]

    def create(self, conn: Connection, commit: bool = True, allow_multiple_schemas: bool = False):
        """
        Creates the schema_migrations information table
        Args:
            conn (Connection): The database connection to create the table.
            commit (bool): If true, the transaction is committed. The default is true.
            allow_multiple_schemas (bool): If true, several pum_migrations tables are allowed in distinct schemas. Default is false.
        """

        if self.exists(conn):
            logger.debug(f"{self.config.pum_migrations_table} table already exists")
            return

        if not allow_multiple_schemas and len(self.exists_in_other_schemas(conn)) > 0:
            raise PumException(
                f"Another {self.config.pum_migrations_table} table exists in another schema (). "
                "Please use the allow_multiple_schemas option to create a new one."
            )

        # Create the schema if it doesn't exist
        create_schema_query = None
        schema = "public"
        table_identifiers = self.config.pum_migrations_table.split(".")
        if len(table_identifiers) == 2:
            schema = table_identifiers[0]
        if schema != "public":
            create_schema_query = sql.SQL("CREATE SCHEMA IF NOT EXISTS {schema};").format(
                schema=sql.Identifier(schema)
            )

        create_table_query = sql.SQL(
            """CREATE TABLE IF NOT EXISTS {pum_migrations_table}
            (
            id uuid DEFAULT gen_random_uuid() PRIMARY KEY,
            date_installed timestamp without time zone NOT NULL DEFAULT now(),
            module character varying(50), -- TODO: NOT NULL,
            version character varying(50) NOT NULL,
            beta_testing boolean NOT NULL DEFAULT false,
            changelog_files text[],
            parameters jsonb,
            migration_table_version character varying(50) NOT NULL DEFAULT {version}
            );
        """
        ).format(
            pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")),
            version=sql.Literal(migration_table_version),
        )

        comment_query = sql.SQL(
            """COMMENT ON TABLE {pum_migrations_table} IS 'version: 1 --  schema_migration table version';"""
        ).format(pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")))

        if create_schema_query:
            execute_sql(conn, create_schema_query)
        execute_sql(conn, create_table_query)
        execute_sql(conn, comment_query)

        logger.info(f"Created {self.config.pum_migrations_table} table")

        if commit:
            conn.commit()

    def set_baseline(
        self,
        conn: Connection,
        version: Version | str,
        beta_testing: bool = False,
        commit: bool = True,
        changelog_files: list[str] = None,
        parameters: dict = None,
    ):
        """
        Sets the baseline into the migration table

        Args:
            conn: Connection
                The database connection to set the baseline version.
            version: Version | str
                The version of the current database to set in the information.
            beta_testing: bool
                If true, the baseline is set to beta testing mode. The default is false.
            commit: bool
                If true, the transaction is committed. The default is true.
        """
        if isinstance(version, Version):
            version = str(version)
        pattern = re.compile(r"^\d+\.\d+\.\d+$")
        if not re.match(pattern, version):
            raise ValueError(f"Wrong version format: {version}. Must be x.x.x")

        query = sql.SQL(
            """
            INSERT INTO {pum_migrations_table} (
            version,
            beta_testing,
            migration_table_version,
            changelog_files,
            parameters
            ) VALUES (
            {version},
            {beta_testing},
            {migration_table_version},
            {changelog_files},
            {parameters}
            )
        """
        ).format(
            version=sql.Literal(version),
            beta_testing=sql.Literal(beta_testing),
            migration_table_version=sql.Literal(migration_table_version),
            pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")),
            changelog_files=sql.Literal(changelog_files or []),
            parameters=sql.Literal(json.dumps(parameters or {})),
        )
        logger.info(f"Setting baseline version {version} in {self.config.pum_migrations_table}")
        conn.execute(query)
        if commit:
            conn.commit()

    def baseline(self, conn: Connection) -> str:
        """
        Returns the baseline version from the migration table
        Args:
            conn: Connection
                The database connection to get the baseline version.
        Returns:
            str: The baseline version.
        """
        query = sql.SQL(
            """
            SELECT version
            FROM {pum_migrations_table}
            WHERE id = (
                SELECT id
                FROM {pum_migrations_table}
                ORDER BY version DESC, date_installed DESC
                LIMIT 1
            )
        """
        ).format(pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")))
        cursor = execute_sql(conn, query)
        return cursor.fetchone()[0]

    def migration_details(self, conn: Connection, version: str = None) -> dict:
        """
        Returns the migration details from the migration table
        Args:
            conn: Connection
                The database connection to get the migration details.
            version: str
                The version of the migration to get details for. If None, last migration is returned.
        Returns:
            dict: The migration details.
        """
        query = None
        if version is None:
            query = sql.SQL(
                """
                SELECT *
                FROM {pum_migrations_table}
                WHERE id = (
                        SELECT id
                        FROM {pum_migrations_table}
                        ORDER BY version DESC, date_installed DESC
                        LIMIT 1
                    )
                ORDER BY date_installed DESC
            """
            ).format(
                pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")),
            )
        else:
            query = sql.SQL(
                """
                SELECT *
                FROM {pum_migrations_table}
                WHERE version = {version}
            """
            ).format(
                pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")),
                version=sql.Literal(version),
            )
        cursor = execute_sql(conn, query)
        row = cursor.fetchone()
        if row is None:
            return None
        return dict(zip([desc[0] for desc in cursor.description], row))

__init__ 

__init__(config: PumConfig)

Initialize the SchemaMigrations class with a database connection and configuration.

Parameters:

Name Type Description Default
config PumConfig

An instance of the PumConfig class containing configuration settings for the PUM system.

 required
Source code in pum/schema_migrations.py 
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def __init__(self, config: PumConfig):
    """
    Initialize the SchemaMigrations class with a database connection and configuration.

    Args:
        config (PumConfig): An instance of the PumConfig class containing configuration settings for the PUM system.
    """
    self.config = config

baseline 

baseline(conn: Connection) -> str

Returns the baseline version from the migration table Args: conn: Connection The database connection to get the baseline version. Returns: str: The baseline version.

Source code in pum/schema_migrations.py 
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def baseline(self, conn: Connection) -> str:
    """
    Returns the baseline version from the migration table
    Args:
        conn: Connection
            The database connection to get the baseline version.
    Returns:
        str: The baseline version.
    """
    query = sql.SQL(
        """
        SELECT version
        FROM {pum_migrations_table}
        WHERE id = (
            SELECT id
            FROM {pum_migrations_table}
            ORDER BY version DESC, date_installed DESC
            LIMIT 1
        )
    """
    ).format(pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")))
    cursor = execute_sql(conn, query)
    return cursor.fetchone()[0]

create 

create(conn: Connection, commit: bool = True, allow_multiple_schemas: bool = False)

Creates the schema_migrations information table Args: conn (Connection): The database connection to create the table. commit (bool): If true, the transaction is committed. The default is true. allow_multiple_schemas (bool): If true, several pum_migrations tables are allowed in distinct schemas. Default is false.

Source code in pum/schema_migrations.py 
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def create(self, conn: Connection, commit: bool = True, allow_multiple_schemas: bool = False):
    """
    Creates the schema_migrations information table
    Args:
        conn (Connection): The database connection to create the table.
        commit (bool): If true, the transaction is committed. The default is true.
        allow_multiple_schemas (bool): If true, several pum_migrations tables are allowed in distinct schemas. Default is false.
    """

    if self.exists(conn):
        logger.debug(f"{self.config.pum_migrations_table} table already exists")
        return

    if not allow_multiple_schemas and len(self.exists_in_other_schemas(conn)) > 0:
        raise PumException(
            f"Another {self.config.pum_migrations_table} table exists in another schema (). "
            "Please use the allow_multiple_schemas option to create a new one."
        )

    # Create the schema if it doesn't exist
    create_schema_query = None
    schema = "public"
    table_identifiers = self.config.pum_migrations_table.split(".")
    if len(table_identifiers) == 2:
        schema = table_identifiers[0]
    if schema != "public":
        create_schema_query = sql.SQL("CREATE SCHEMA IF NOT EXISTS {schema};").format(
            schema=sql.Identifier(schema)
        )

    create_table_query = sql.SQL(
        """CREATE TABLE IF NOT EXISTS {pum_migrations_table}
        (
        id uuid DEFAULT gen_random_uuid() PRIMARY KEY,
        date_installed timestamp without time zone NOT NULL DEFAULT now(),
        module character varying(50), -- TODO: NOT NULL,
        version character varying(50) NOT NULL,
        beta_testing boolean NOT NULL DEFAULT false,
        changelog_files text[],
        parameters jsonb,
        migration_table_version character varying(50) NOT NULL DEFAULT {version}
        );
    """
    ).format(
        pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")),
        version=sql.Literal(migration_table_version),
    )

    comment_query = sql.SQL(
        """COMMENT ON TABLE {pum_migrations_table} IS 'version: 1 --  schema_migration table version';"""
    ).format(pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")))

    if create_schema_query:
        execute_sql(conn, create_schema_query)
    execute_sql(conn, create_table_query)
    execute_sql(conn, comment_query)

    logger.info(f"Created {self.config.pum_migrations_table} table")

    if commit:
        conn.commit()

exists 

exists(conn: Connection)

Checks if the schema_migrations information table exists Args: conn (Connection): The database connection to check for the existence of the table. Returns: bool: True if the table exists, False otherwise.

Source code in pum/schema_migrations.py 
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def exists(self, conn: Connection):
    """
    Checks if the schema_migrations information table exists
    Args:
        conn (Connection): The database connection to check for the existence of the table.
    Returns:
        bool: True if the table exists, False otherwise."""

    schema, table = self._pum_migrations_table_schema_name()
    query = sql.SQL(
        """
    SELECT EXISTS (
        SELECT 1
        FROM information_schema.tables
        WHERE table_name = {table} AND table_schema = {schema}
    );
    """
    ).format(
        schema=sql.Literal(schema),
        table=sql.Literal(table),
    )

    cursor = execute_sql(conn, query)
    return cursor.fetchone()[0]

exists_in_other_schemas 

exists_in_other_schemas(conn: Connection) -> List[str]

Checks if the schema_migrations information table exists in other schemas Args: conn (Connection): The database connection to check for the existence of the table. Returns: List[str]: List of schemas where the table exists.

Source code in pum/schema_migrations.py 
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def exists_in_other_schemas(self, conn: Connection) -> List[str]:
    """
    Checks if the schema_migrations information table exists in other schemas
    Args:
        conn (Connection): The database connection to check for the existence of the table.
    Returns:
        List[str]: List of schemas where the table exists.
    """
    schema, table = self._pum_migrations_table_schema_name()
    query = sql.SQL(
        """
        SELECT table_schema
        FROM information_schema.tables
        WHERE table_name = {table} AND table_schema != {schema}
    """
    ).format(
        schema=sql.Literal(schema),
        table=sql.Literal(table),
    )

    cursor = execute_sql(conn, query)
    return [row[0] for row in cursor.fetchall()]

migration_details 

migration_details(conn: Connection, version: str = None) -> dict

Returns the migration details from the migration table Args: conn: Connection The database connection to get the migration details. version: str The version of the migration to get details for. If None, last migration is returned. Returns: dict: The migration details.

Source code in pum/schema_migrations.py 
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def migration_details(self, conn: Connection, version: str = None) -> dict:
    """
    Returns the migration details from the migration table
    Args:
        conn: Connection
            The database connection to get the migration details.
        version: str
            The version of the migration to get details for. If None, last migration is returned.
    Returns:
        dict: The migration details.
    """
    query = None
    if version is None:
        query = sql.SQL(
            """
            SELECT *
            FROM {pum_migrations_table}
            WHERE id = (
                    SELECT id
                    FROM {pum_migrations_table}
                    ORDER BY version DESC, date_installed DESC
                    LIMIT 1
                )
            ORDER BY date_installed DESC
        """
        ).format(
            pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")),
        )
    else:
        query = sql.SQL(
            """
            SELECT *
            FROM {pum_migrations_table}
            WHERE version = {version}
        """
        ).format(
            pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")),
            version=sql.Literal(version),
        )
    cursor = execute_sql(conn, query)
    row = cursor.fetchone()
    if row is None:
        return None
    return dict(zip([desc[0] for desc in cursor.description], row))

set_baseline 

set_baseline(conn: Connection, version: Version | str, beta_testing: bool = False, commit: bool = True, changelog_files: list[str] = None, parameters: dict = None)

Sets the baseline into the migration table

Parameters:

Name Type Description Default
conn Connection

Connection The database connection to set the baseline version.

 required
version Version | str

Version | str The version of the current database to set in the information.

 required
beta_testing bool

bool If true, the baseline is set to beta testing mode. The default is false.

 False
commit bool

bool If true, the transaction is committed. The default is true.

 True
Source code in pum/schema_migrations.py 
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def set_baseline(
    self,
    conn: Connection,
    version: Version | str,
    beta_testing: bool = False,
    commit: bool = True,
    changelog_files: list[str] = None,
    parameters: dict = None,
):
    """
    Sets the baseline into the migration table

    Args:
        conn: Connection
            The database connection to set the baseline version.
        version: Version | str
            The version of the current database to set in the information.
        beta_testing: bool
            If true, the baseline is set to beta testing mode. The default is false.
        commit: bool
            If true, the transaction is committed. The default is true.
    """
    if isinstance(version, Version):
        version = str(version)
    pattern = re.compile(r"^\d+\.\d+\.\d+$")
    if not re.match(pattern, version):
        raise ValueError(f"Wrong version format: {version}. Must be x.x.x")

    query = sql.SQL(
        """
        INSERT INTO {pum_migrations_table} (
        version,
        beta_testing,
        migration_table_version,
        changelog_files,
        parameters
        ) VALUES (
        {version},
        {beta_testing},
        {migration_table_version},
        {changelog_files},
        {parameters}
        )
    """
    ).format(
        version=sql.Literal(version),
        beta_testing=sql.Literal(beta_testing),
        migration_table_version=sql.Literal(migration_table_version),
        pum_migrations_table=sql.Identifier(*self.config.pum_migrations_table.split(".")),
        changelog_files=sql.Literal(changelog_files or []),
        parameters=sql.Literal(json.dumps(parameters or {})),
    )
    logger.info(f"Setting baseline version {version} in {self.config.pum_migrations_table}")
    conn.execute(query)
    if commit:
        conn.commit()