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hamidmujtabahamidmujtaba
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Added SQLServer_Persister
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‎py2store/persisters/sqlserver_w_pyodbc.py‎

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

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