Added SQLServer_Persister

py2store/persisters/sqlserver_w_pyodbc.py

@@ -0,0 +1,224 @@
+import platform
+import subprocess
+from collections.abc import MutableMapping
+from py2store.util import ModuleNotFoundErrorNiceMessage
+
+with ModuleNotFoundErrorNiceMessage():
+    import pyodbc
+
+
+class SQLServerPersister(MutableMapping):
+    def __init__(self,
+                 conn_protocol='tcp',
+                 host='localhost',
+                 port='1433',
+                 db_username='SA',
+                 db_pass='Admin123x',
+                 db_name='py2store',
+                 table_name='py2store_default_table',
+                 key_fields=('id',),
+                 data_fields=('name',),
+                 create_table_if_not_exists=True,
+                 NVARCHAR_LENGTH=100):
+        """
+
+        :param conn_protocol: Which connection protocol to use to connect to MS SQLServer
+        :param host: HOST where SQLServer is running
+        :param port: PORT of SQLServer
+        :param db_username: Username tht will be used to connect to the SQLServer
+        :param db_pass: Database password
+        :param db_name: Database Name, to connect to
+        :param table_name: Table name on which you are going to perform CRUD ops
+        :param key_fields: Primary key fields of the table
+        :param data_fields: Non primary fields of the table
+        :param create_table_if_not_exists: Flag to create database table if it doesn't exist previously
+        :param NVARCHAR_LENGTH: Length of the NVARCHAR column types in case the table isn't created previously
+        """
+
+        self.__check_dependencies()
+        self._sql_server_client = pyodbc.connect('DRIVER={{ODBC Driver 17 for SQL Server}};'
+                                                 'SERVER={}:{},{};'
+                                                 'DATABASE={};'
+                                                 'UID={};'
+                                                 'PWD={}'
+                                                 .format(conn_protocol, host, port, db_name, db_username, db_pass))
+
+        self._cursor = self._sql_server_client.cursor()
+
+        self._table_name = table_name
+        self.key_fields = key_fields
+        self.data_fields = data_fields
+        self.NVARCHAR_LENGTH = NVARCHAR_LENGTH
+
+        if create_table_if_not_exists:
+            self.__create_table()
+
+    def __create_table(self):
+        """
+        Create table if it doesn't exist previously
+        :return:
+        """
+        if not self._cursor.tables(table=self._table_name, tableType='TABLE').fetchone():
+            base_query = 'CREATE TABLE {table_name} ({attributes})'
+            attributes = ''
+
+            for key_field in self.key_fields:
+                attributes += '{column} {type} PRIMARY KEY,'.format(column=key_field,
+                                                                    type='NVARCHAR({})'.format(self.NVARCHAR_LENGTH))
+
+            for data_field in self.data_fields:
+                attributes += '{column} {type},'.format(column=data_field, type='NVARCHAR(100)')
+
+            create_table_query = base_query.format(table_name=self._table_name, attributes=attributes)
+
+            self._cursor.execute(create_table_query)
+            self._sql_server_client.commit()
+
+    @staticmethod
+    def __check_dependencies():
+        """
+        Checks for the required dependencies for the OS
+        Currently checks are there for a Ubuntu machine only, more can be added
+        :return:
+        """
+        if 'ubuntu' in platform.platform().lower():
+            result = subprocess.Popen(["dpkg", "-s", "msodbcsql17"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+            out, err = result.communicate()
+            if not out:
+                raise ModuleNotFoundError("ODBC Driver for SQL Server is missing. Please refer "
+                                          "https://docs.microsoft.com/en-us/sql/connect/odbc/linux-mac/installing-the-"
+                                          "microsoft-odbc-driver-for-sql-server?view=sql-server-2017")
+
+    def __getitem__(self, k):
+        base_query = "SELECT * from {table} where {{conditions}}".format(table=self._table_name)
+
+        conditions = ''
+        for key, val in k.items():
+            conditions += "{key} = '{val}' AND ".format(key=key, val=val)
+
+        select_query = base_query.format(conditions=conditions)
+        select_query = select_query.rstrip('AND ')
+
+        self._cursor.execute(select_query.format(value=k))
+        record = self._cursor.fetchone()
+        if record:
+            return record
+        raise KeyError(f"No record found for primary_key: {k}")
+
+    def __setitem__(self, k, v):
+        base_query = "INSERT into {table} ({{attributes}}) VALUES ({{values}})".format(table=self._table_name)
+
+        attributes = ','.join([key for key in k])
+        values = ','.join(["'{}'".format(val) for val in v])
+        insert_query = base_query.format(attributes=attributes, values=values)
+
+        try:
+            self._cursor.execute(insert_query)
+        except pyodbc.IntegrityError as e:
+            raise KeyError("Cannot insert a duplicate entry")
+
+        self._sql_server_client.commit()
+
+    def __delitem__(self, k):
+        base_query = "DELETE FROM {table} where {{conditions}}".format(table=self._table_name)
+
+        conditions = ''
+        for key, val in k.items():
+            conditions += "{key} = '{val}' AND ".format(key=key, val=val)
+
+        select_query = base_query.format(conditions=conditions)
+        select_query = select_query.rstrip('AND ')
+
+        self._cursor.execute(select_query.format(value=k))
+        self._sql_server_client.commit()
+
+    def __iter__(self):
+        select_all_query = "SELECT * from {table};".format(table=self._table_name)
+        self._cursor.execute(select_all_query)
+        records = self._cursor.fetchall()
+
+        for record in records:
+            yield record
+
+    def __len__(self):
+        select_all_query = "SELECT * from {table};".format(table=self._table_name)
+        self._cursor.execute(select_all_query)
+        records = self._cursor.fetchall()
+        return len(records)
+
+
+def test_sqlserver_persister():
+    """
+    A test case for the persister which performs many actions
+
+    Output of the test case is given below:
+
+                Adding Records
+                =========================
+                Adding a Duplicate Record
+                Cannot Enter a Duplicate Record
+                =========================
+                Fetching Records
+                ('1', 'Test 1')
+                ('2', 'Test 2')
+                ('3', 'Test 3')
+                =========================
+                Iterating over the records
+                ('1', 'Test 1')
+                ('2', 'Test 2')
+                ('3', 'Test 3')
+                =========================
+                Getting the length
+                3
+                =====================
+                Deleting Records
+                =====================
+                Getting the length AGAIN after deletion
+                0
+                =====================
+
+    :return:
+    """
+    sql_server_persister = SQLServerPersister()
+
+    print("Adding Records")
+    sql_server_persister[('id', 'name',)] = ('1', 'Test 1',)
+    sql_server_persister[('id', 'name',)] = ('2', 'Test 2',)
+    sql_server_persister[('id', 'name',)] = ('3', 'Test 3',)
+    print("=========================")
+
+    print("Adding a Duplicate Record")
+    try:
+        sql_server_persister[('id', 'name',)] = ('1', 'Test 4',)
+    except KeyError:
+        print("Cannot Enter a Duplicate Record")
+    print("=========================")
+
+    print("Fetching Records")
+    print(sql_server_persister[{'id': '1',
+                                'name': 'Test 1'}])
+    print(sql_server_persister[{'name': 'Test 2'}])
+    print(sql_server_persister[{'id': 3}])
+    print("=========================")
+
+    print("Iterating over the records")
+    for record in sql_server_persister:
+        print(record)
+    print("=========================")
+
+    print("Getting the length")
+    print(len(sql_server_persister))
+    print("=====================")
+
+    print("Deleting Records")
+    del sql_server_persister[{'id': '1'}]
+    del sql_server_persister[{'name': 'Test 2'}]
+    del sql_server_persister[{'id': '3', 'name': 'Test 3'}]
+    print("=====================")
+
+    print("Getting the length AGAIN after deletion")
+    print(len(sql_server_persister))
+    print("=====================")
+
+
+test_sqlserver_persister()