If I understand correctly, the problem is that you want to generate different data every time. To do that, you need to:

• Currently the LoginData attributes are generated when the class is defined. If you want them to be different for each instance, make them instance attributes and set them in the __init__() method.

• You need to create a new LoginData instance in every iteration of the for loop in input_data().

Code:

from faker import Faker
import random


class LoginData:

    def __init__(self):
        fake = Faker()
        self.password = "password@123"
        self.email = fake.email()
        self.username = fake.first_name()
        self.first_name = fake.first_name()
        self.last_name = fake.last_name()
        self.phone = random.randint(9000000000, 9999999999)
        self.city = fake.city()
        self.about = "This is a sample text : about"

    def get_json(self):
        p = {
            'password': self.password,
            'email': self.email,
            'username': self.first_name,
            'first_name': self.first_name,
            'last_name': self.last_name,
            'phone': self.phone,
            'city': self.city,
            'about': self.about
        }
        return p



def input_data(x):
    for i in range(0, x):
        logindata = LoginData()
        print(logindata.get_json())


def main():
    no_of_input = 5
    input_data(no_of_input)


main()

Note that get_json() still returns a Python dict, not JSON. For JSON, you can use the json module in the standard library:

import json

and in get_json()

return json.dumps(p)

You do not need to use OrderedDict: JSON format may not (and will not) save order of items. Even if order will be saved in the file - it will breaks when another project will parse that file.

You just need to use dict. Also it will be much more faster.

To save the order of items you should explicitly preserve the index of an each element. Like this:

from json import dumps
from faker import Faker
import collections
import json

def fake_person_generator(length, fake):
    for x in range(length):  # xrange in Python 2.7
        yield {'last_name': fake.last_name(),
               'first_name': fake.first_name(),
               'street_address': fake.street_address(),
               'email': fake.email(),
               'index': x}

database = []
filename = '1M'
length   = 1000000
fake     = Faker() # <--- Forgot this
fpg = fake_person_generator(length, fake)
with open('%s.json' % filename, 'w') as output:
    output.write('[')  # to made json file valid according to JSON format
    for person in fpg:
        json.dump(person, output)
    output.write(']')  # to made json file valid according to JSON format
print "Done."