[[:oktatas:programozás:python:adatbázis|< Adatbázis]]

====== Interfész használata ======

  * **Szerző:** Sallai András
  * Copyright (c) 2020, Sallai András
  * Licenc: [[https://creativecommons.org/licenses/by-sa/4.0/|CC BY-SA 4.0]]
  * Web: https://szit.hu

===== Bevezetés =====

A Python nyelv nem támogatja az interfész használatát, de használhatunk
egy interface modult. 

===== Employee.py =====

<code python Employee.py>
class Employee:
    def __init__(self, id, name, city, salary):
        self.id = id
        self.name = name
        self.city = city
        self.salary = salary
</code>


===== iDatabase.py =====

<code python iDatabase.py>
from interface import Interface

class iDatabase(Interface):

    def connectDb(self):
        pass
</code>

===== Mariadb.py =====

<code python Mariadb.py>
from interface import implements
from iDatabase import iDatabase
from mariadb import connect, Error
import sys

class Mariadb(implements(iDatabase)):
    def tryConnectDb(self):
        print('Működik')
        config = {
            'host': 'localhost',
            'user': 'feherbt',
            'password': 'titok'
        }
        conn = connect(**config, database='feherbt')
        return conn

    def connectDb(self):
        try:
            conn = self.tryConnectDb()
        except Error as err:
            print('Hiba! A kapcsolódás sikertelen!')
            print(err, file=sys.stderr)
        return conn


if __name__ == '__main__':
    Mariadb().connectDb()
</code>

===== DataManager.py =====

A "database: iDatabase" állítás jelzi, hogy iDatabase paramétert várunk, de
maga a Python nyelv nem követeli meg, hogy ténylegesen azt adjuk át paraméterként
a hívás helyén. 

<code python DataManager.py>
from iDatabase import iDatabase
from Mariadb import Mariadb
from Employee import Employee

class DataManager:
    def __init__(self,  database: iDatabase):
        self.database = database

    def getEmployees(self):
        conn = self.database.connectDb()
        cur = conn.cursor()
        sql = 'select * from employees'
        cur.execute(sql)
        
        employeeList = []
        for (id, name, city, salary) in cur:
            employee = Employee(id, name, city, salary)
            employeeList.append(employee)
        return employeeList
    
    def insertEmployee(self, employee: Employee):
        conn = self.database.connectDb()
        cur = conn.cursor()
        sql = """
                insert into employees
                (name, city, salary) values
                (?, ?, ?)
              """ 
        values = (employee.name, employee.city, employee.salary)
        cur.execute(sql, values)
        conn.commit()
        conn.close()

if __name__ == '__main__':
    data_manager = DataManager(Mariadb())
</code>

===== program01.py =====

<code python program01.py>
from DataManager import DataManager
from Mariadb import Mariadb
from Employee import Employee

data_manager = DataManager(Mariadb())

employee = Employee(0, 'Reke Imre', 'Szeged', 4740000)
data_manager.insertEmployee(employee)

employees = data_manager.getEmployees()
    
for employee in employees:
    print(employee.name)
</code>