title: How to set default selected value in django ModelForm ForeignKey
body: <p>I want to set select option preselected on my Model's ForeignKeyField in ModelForm. Below are my model and form. I want to only set preselected <code>value=1</code> for <code>State</code> field in my ModelForm. So that it shown to the user as already selected option.</p>
  
  <pre><code>Customer Model:
  
  
  class Customer(models.Model):
      """
      Customer model
      """
  
      GENDER_CHOICES = (('M', 'M'),
                       ('F', 'F'))
      SDW_CHOICES = (('S/o', 'S/o'),
                     ('D/o', 'D/o'),
                     ('W/o', 'W/o'))
  
      name = models.CharField(verbose_name='customer name', max_length=50,
                              help_text='max length 50 characters')
      guardian_name = models.CharField(verbose_name='customer guardian name', max_length=50,
                                       help_text='max length 50 characters')
      phone_no_1 = models.CharField(verbose_name='customer phone number 1', max_length=10, null=True, blank=True,
                                    help_text='max length 10 digits')
      phone_no_2 = models.CharField(verbose_name='customer phone number 2', max_length=10, null=True, blank=True,
                                    help_text='max length 10 digits')
      address = models.CharField(verbose_name='customer address', max_length=150,
                                 help_text='max length 150 characters')
      state = models.ForeignKey(State, help_text='Please select from list')
      district = models.ForeignKey(District, help_text='Please select from list')
      village_or_city = models.ForeignKey(VillageOrCity, help_text='Please select from list')
      created_on = models.DateTimeField(verbose_name='customer added on', auto_now_add=True)
      updated_on = models.DateTimeField(verbose_name='customer last modified', auto_now=True)
      remark = models.TextField(max_length=150, null=True, blank=True, help_text='max length 150 characters')
      gender = models.CharField(max_length=1, choices=GENDER_CHOICES, help_text='Please select from list')
      image = models.ImageField(upload_to=MEDIA_ROOT, default=DEFAULT_USER_IMAGE)
      sdw = models.CharField(verbose_name='Son/daughter/wife of', max_length=3, choices=SDW_CHOICES,
                             help_text='Please select from list')
      caste = models.ForeignKey(Caste, help_text='Please select from list')
      created_by = models.ForeignKey(User, related_name='created_by', null=True)
      updated_by = models.ForeignKey(User, related_name='updated_by', null=True)
  
  
  CreateCustomerForm:
  
  class CreateCustomerForm(forms.ModelForm):
  """
  CreateCustomerForm class. Renders Customer model form
  """
  
  class Meta:
  
      model = Customer
      fields = ('name', 'sdw', 'guardian_name', 'phone_no_1',
                'phone_no_2', 'address', 'state', 'district',
                'village_or_city', 'remark', 'gender', 'caste',
                'image'
                )
      widgets = {
                  'name': forms.TextInput(attrs={'placeholder': 'Enter customer name',
                                                 'required': 'required',
                                                 'autofocus': 'autofocus', 'size': "50"
                                                 }
                                          ),
                  'sdw': forms.Select(attrs={'required': 'required',
                                             }
                                      ),
                  'guardian_name': forms.TextInput(attrs={'placeholder': 'Enter guardian name',
                                                          'required': 'required', 'size': "50"
                                                          }
                                                   ),
                  'phone_no_1': forms.TextInput(attrs={'placeholder': 'Enter phone number',
                                                       'size': "50"
                                                       }
                                                ),
                  'phone_no_2': forms.TextInput(attrs={'placeholder': 'Enter phone number',
                                                       'size': "50"
                                                       }
                                                ),
                  'address': forms.TextInput(attrs={'placeholder': 'Enter address',
                                                    'required': 'required', 'size': "50"
                                                    }
                                                   ),
                  'state': forms.Select(attrs={'required': 'required',
                                               }
                                        ),
                  'district': forms.Select(attrs={'required': 'required',
                                                  }
                                           ),
                  'village_or_city': forms.Select(attrs={'required': 'required',
                                                         }
                                                  ),
                  'remark': forms.Textarea(attrs={'placeholder': 'Enter remark',
                                                   }
                                            ),
                  'gender': forms.Select(attrs={'required': 'required',
                                                }
                                         ),
                  'caste': forms.Select(attrs={'required': 'required',
                                               }
                                        ),
                  }
  </code></pre>