Customize username and password field in Django?

Question

First, How can I set min_length for username? ChachaUser._meta.get_field('username').min_length = 2 doesn't work.

Second, How can I place placeholder for password1 and password2? forms.PasswordInput(attrs={'placeholder' : "6자리 이상"}), doesn't work.

This is my customized User model and UserCreationForm.

models.py

from django.core.validators import RegexValidator
from django.contrib.auth.models import AbstractUser
from django.db import models


GENDER_CHOICES = (
    ('M', '남'),
    ('F', '여'),
)

phone_regex = RegexValidator(
    regex=r'^\d{11}$',
    message=" '-' 없이 입력해주세요",
)

username_regex = RegexValidator(
    regex=r'^[0-9a-zA-Z]*$',
    message='아이디는 영어와 숫자로만 구성되어야 합니다.'
)



class ChachaUser(AbstractUser):

    birth = models.DateField("생년월일")
    name = models.CharField(
        "이 름",
        max_length=4
    )
    gender = models.CharField(
        "성 별",
        max_length=1,
        choices=GENDER_CHOICES,
        default='M'
    )

    phone_number = models.CharField(
        "핸드폰",
        validators=[phone_regex],
        max_length=11
    )

    job = models.CharField(
        "직 업",
        max_length=20,
    )

    # python manage.py createsuperuser 할 때 나오는 항목
    REQUIRED_FIELDS = [
        'birth',
        'name',
        'gender',
        'phone_number',
        'job',
        'email'
    ]

ChachaUser._meta.get_field('username').verbose_name = '아이디'
ChachaUser._meta.get_field('username').validators = [username_regex]
ChachaUser._meta.get_field('username').max_length = 20
ChachaUser._meta.get_field('username').min_length = 2

forms.py

from django import forms
from django.contrib.auth.forms import UserCreationForm
from django.contrib.auth import get_user_model


class MyUserCreationForm(UserCreationForm):

    birth = forms.DateField(
        label="생년월일",
        widget=forms.SelectDateWidget(
            years=range(1970, 2015)
        ),
    )

    class Meta(UserCreationForm.Meta):
        model = get_user_model()
        fields = UserCreationForm.Meta.fields + (
            'name',
            'gender',
            'birth',
            'phone_number',
            'job',
        )
        exclude = ('email', )
        widgets = {
            'username' : forms.TextInput(
                attrs={'placeholder': '알파벳, 숫자만 가능(20자 이내)'}
            ),
            'phone_number' : forms.TextInput(
                attrs={'placeholder' : "ex) 01012341234"}
            ),
            'job' : forms.TextInput(
                attrs={'placeholder' : "ex) 한국대 철학과, 선생님 등(20자 이내)"}
            ),
            'password1' : forms.PasswordInput(
                attrs={'placeholder' : "6자리 이상"}
            ),
            'password2' : forms.PasswordInput(
                attrs={'placeholder' : "6자리 이상"}
            ),
        }

Answer 1

For first question:

from django.core import validators    
class ChachaUser(AbstractUser):
    ..................
    AbstractUser._meta.get_field('username').validators=[validators.MinLengthValidator(2)]

For second question your couldn't change password1 in Meta.widgets because it is not a model field. You can override widget in __init__ method instead.