The following code connects to the Postgresql. In the database there is a table 'country_details'. The first column has the names of the countries. I want the country names in a list. How do I rewrite this code in OOP.

#returns the list of countries from the database
def connect_db():
    con = psycopg2.connect(host='localhost',
                       database='Country Details',
                       user='postgres',
                       password='root')
    cur = con.cursor()
    cur.execute("SELECT country_name FROM country_details")
    rows = cur.fetchall()
    country_list = c_list(rows)
    con.close()
    cur.close()
    return country_list

#converts the list of tuples to a list of strings
def c_list(rows):
    country_list = []
    for row in range(len(rows)):
        country_list.append(rows[row][0])
    return country_list

CodePudding user response：

Heres an example of the same code but with a class.

class ConnectDB:
    # Special method that runs when initialized
    def __init__(self):
        self.db = self.connect()  
        
    def connect(self):
        return psycopg2.connect(host='localhost',
                       database='Country Details',
                       user='postgres',
                       password='root')
                       
    
    def _tuplesToStrings(self,rows):
        return [rows[row][0] for row in range(len(rows))]
        
        
    def getCountries(self):
        cur = self.db.cursor()
        cur.execute("SELECT country_name FROM country_details")
        rows = cur.fetchall()
        country_list = self._tuplesToStrings(rows)
        cur.close()
        return country_list
   
    # Special method that runs when the object falls out of scope.
    def __del__(self):
      self.db.close()
        

And heres how you would use it.

db = ConnectDB()
print(db. getCountries())

I recommend you watch this video Python Object Oriented Programming (OOP) - For Beginners it helped me out. (https://youtu.be/JeznW_7DlB0)