Merge pull request #727 from eschizoid/feature/refactor-driver

Feature/refactor driver

optimus/io/abstract_driver.py

@@ -0,0 +1,56 @@
+from abc import abstractmethod, ABC
+from enum import Enum
+
+
+class AbstractDriver(ABC):
+    """Base class for all database implementations"""
+
+    @abstractmethod
+    def properties(self) -> Enum:
+        """
+        Returns an enum containing the following database properties:
+
+            * name
+            * port
+            * java_class
+            * table_name
+
+        :return: en enum of type ``DriverProperties``
+        """
+        pass
+
+    @abstractmethod
+    def url(self, *args, **kwargs) -> str:
+        """
+        Returns a string connection to the underlying database implementation.
+        :param kwargs: connection properties
+        :return: the connection string
+        """
+        pass
+
+    @abstractmethod
+    def table_names_query(self, *args, **kwargs) -> str:
+        """
+        Returns the query for all table names in the database.
+        :param kwargs: query parameters
+        :return: a query for all the tables in a given database
+        """
+        pass
+
+    @abstractmethod
+    def table_name_query(self, *args, **kwargs) -> str:
+        """
+        Returns the query for a table name in the database.
+        :param kwargs: query parameters
+        :return: a query for all the tables in a given database
+       """
+        pass
+
+    @abstractmethod
+    def count_query(self, *args, **kwargs) -> str:
+        """
+        Returns the query for counting the rows in a given table.
+        :param kwargs: query parameters
+        :return: a query to count the number of rows in a table
+        """
+        pass

optimus/io/cassandra.py

@@ -0,0 +1,26 @@
+from enum import Enum
+
+from singleton_decorator import singleton
+
+from optimus.io.abstract_driver import AbstractDriver
+from optimus.io.properties import DriverProperties
+
+
+@singleton
+class CassandraDriver(AbstractDriver):
+    """Cassandra Database"""
+
+    def properties(self) -> Enum:
+        return DriverProperties.CASSANDRA
+
+    def url(self, *args, **kwargs) -> str:
+        return ""
+
+    def table_names_query(self, *args, **kwargs) -> str:
+        pass
+
+    def table_name_query(self, *args, **kwargs) -> str:
+        pass
+
+    def count_query(self, *args, **kwargs) -> str:
+        pass

optimus/io/driver_context.py

@@ -0,0 +1,33 @@
+from enum import Enum
+
+from optimus.io.abstract_driver import AbstractDriver
+
+
+class DriverContext:
+    """Driver context holding a reference to the underlying driver implementation"""
+
+    def __init__(self, driver: AbstractDriver) -> None:
+        self._driver = driver
+
+    @property
+    def driver(self) -> AbstractDriver:
+        return self._driver
+
+    @driver.setter
+    def driver(self, driver: AbstractDriver) -> None:
+        self._driver = driver
+
+    def properties(self) -> Enum:
+        return self._driver.properties()
+
+    def url(self, *args, **kwargs) -> str:
+        return self._driver.url(*args, **kwargs)
+
+    def table_names_query(self, *args, **kwargs) -> str:
+        return self._driver.table_names_query(*args, **kwargs)
+
+    def table_name_query(self, *args, **kwargs) -> str:
+        return self._driver.table_name_query(*args, **kwargs)
+
+    def count_query(self, *args, **kwargs) -> str:
+        return self._driver.count_query(*args, **kwargs)

optimus/io/factory.py

@@ -0,0 +1,52 @@
+from optimus.helpers.raiseit import RaiseIt
+from optimus.io.abstract_driver import AbstractDriver
+from optimus.io.cassandra import CassandraDriver
+from optimus.io.mysql import MySQLDriver
+from optimus.io.oracle import OracleDriver
+from optimus.io.postgresql import PostgreSQLDriver
+from optimus.io.presto import PrestoDriver
+from optimus.io.properties import DriverProperties
+from optimus.io.redshift import RedshiftDriver
+from optimus.io.sqlite import SQLiteDriver
+from optimus.io.sqlserver import SQLServerDriver
+
+
+class DriverFactory:
+    """Database driver factory. This database driver factory currently supports the following implementations:
+
+        * Cassandra
+        * MySQL
+        * Oracle
+        * Postgres
+        * Presto
+        * Redshift
+        * SQLite
+        * SQLServer
+    """
+
+    @staticmethod
+    def get(driver_type) -> AbstractDriver:
+        """
+        Returns a driver implementation given a database name
+
+        :param driver_type: name of the database
+        :return: a database driver
+        """
+        if driver_type == DriverProperties.CASSANDRA.value["name"]:
+            return CassandraDriver()
+        elif driver_type == DriverProperties.MYSQL.value["name"]:
+            return MySQLDriver()
+        elif driver_type == DriverProperties.ORACLE.value["name"]:
+            return OracleDriver()
+        elif driver_type == DriverProperties.POSTGRESQL.value["name"]:
+            return PostgreSQLDriver()
+        elif driver_type == DriverProperties.PRESTO.value["name"]:
+            return PrestoDriver()
+        elif driver_type == DriverProperties.REDSHIFT.value["name"]:
+            return RedshiftDriver()
+        elif driver_type == DriverProperties.SQLITE.value["name"]:
+            return SQLiteDriver()
+        elif driver_type == DriverProperties.SQLSERVER.value["name"]:
+            return SQLServerDriver()
+        else:
+            RaiseIt.value_error(driver_type, [database["name"] for database in DriverProperties.list()])