from mysql.connector import MySQLConnection, Error,connect

db_username='root'
db_password='root'
database_name='testdb'
db_host='127.0.0.1'

def read_file(filename):
    with open(filename, 'rb') as f:
        photo = f.read()
    return photo

def write_file(data, filename):
    with open(filename, 'wb') as f:
        f.write(data)

def write_blob(author_id, filename):
    # read file
    data = read_file(filename)
    # prepare update query and data
    query = "INSERT INTO `images` (`id`,`photo`) VALUES (%s,%s)"
    args = (author_id,data)
    try:
        cnx = MySQLConnection(user=db_username, password=db_password, host=db_host, port='8889',  \
 unix_socket='/Applications/MAMP/tmp/mysql/mysql.sock', database=database_name)
        cursor = cnx.cursor()
        cursor.execute(query, args)
        cnx.commit()
    except Exception as e:
        print(e)
    finally:
        cursor.close()
        cnx.close()

def update_blob(author_id, filename):
    # read file
    data = read_file(filename)
    # prepare update query and data
    query = "UPDATE images " \
            "SET photo = %s " \
            "WHERE id  = %s"
    args = (data, author_id) 
    try:
        cnx = MySQLConnection(user=db_username, password=db_password, host=db_host, port='8889',  \
 unix_socket='/Applications/MAMP/tmp/mysql/mysql.sock', database=database_name)
        cursor = cnx.cursor()
        cursor.execute(query, args)
        cnx.commit()
    except Exception as e:
        print(e)
    finally:
        cursor.close()
        cnx.close()

def read_blob(author_id, filename):
    # select photo column of a specific author
    query = "SELECT photo FROM images WHERE id = %s"
    try:
        cnx = MySQLConnection(user=db_username, password=db_password, host=db_host, port='8889',  \
 unix_socket='/Applications/MAMP/tmp/mysql/mysql.sock', database=database_name)
        cursor = cnx.cursor()
        cursor.execute(query, (author_id,))
        photo=cursor.fetchone()[0]
        # write blob data into a file
        write_file(photo, filename)
    except Exception as e:
        print(e)
    finally:
        cursor.close()
        cnx.close()

def main():
    write_blob(1,"whyno.jpg")
    update_blob(1, "svg_map.jpg")
    read_blob(1,"02.jpg")

if __name__ == '__main__':
    main()