ChoiceField: Select a valid choice. That is not one of the available choices

Question

models.py:

from django.db import models
from django.contrib.auth.models import User as BaseUser

CHOICE_GENDER = (('1', 'Male'), ('2', 'Female'))


class Location(models.Model):
    city = models.CharField(max_length=75)
    country = models.CharField(max_length=25)

    def __unicode__(self):
        return ', '.join([self.city, self.state])


class Users(BaseUser):
    user = models.OneToOneField(BaseUser, on_delete=models.CASCADE)
    gender = models.IntegerField(choices=CHOICE_GENDER)
    birth = models.DateField()
    location = models.ForeignKey(Location)

    class Meta:
        ordering = ('user',)

forms.py:

from django.contrib.auth.forms import UserCreationForm
from django import forms
from .models import Users, Location, CHOICE_GENDER


class LocationForm(forms.ModelForm):
    city = forms.CharField(max_length=75)
    country = forms.CharField(max_length=25)

    class Meta:
        model = Location
        fields = ('city', 'country',)


class RegistrationForm(UserCreationForm):
    email = forms.CharField(max_length=75)
    first_name = forms.CharField(max_length=30)
    last_name = forms.CharField(max_length=30)
    gender = forms.ChoiceField(choices=CHOICE_GENDER)
    birth = forms.DateField()
    location = LocationForm()

    class Meta:
        model = Users
        fields = ('username', 'email', 'first_name', 'last_name', 'gender', 'birth',)

    def save(self, commit=True):
        user = super(RegistrationForm, self).save(commit=False)
        user.email = self.cleaned_data['email']
        user.first_name = self.cleaned_data['first_name']
        user.last_name = self.cleaned_data['last_name']
        user.gender = self.cleaned_data['gender']
        user.birth = self.cleaned_data['birth']
        loc = LocationForm(city=self.cleaned_data['city'], country=self.cleaned_data['country'])
        user.location = loc
        if commit:
            user.save()
        return user

I can't manage to get past the error described in the title. I've tried everything from the suggestions in other questions about the same subject but it still doesn't work.

Solution

You have set datatype as Integer

gender = models.**IntegerField**(choices=CHOICE_GENDER)

and your choices are given in String

CHOICE_GENDER = (('1', 'Male'), ('2', 'Female'))

Instead of '1' it should be 1

CHOICE_GENDER = ((1, 'Male'), (2, 'Female'))