Integrity error in Django
<p>While I use POST to create new fields in database getting an error as follows,</p>

<pre><code>IntegrityError at /api/signup/wallet/
SignUp_wallet_table.bank_ac_num_id may not be NULL
Exception Type: IntegrityError
Exception Value:    
SignUp_wallet_table.bank_ac_num_id may not be NULL
</code></pre>

<p>I also  submitting my <strong>models.py</strong> file here</p>

<p><strong>#models.py</strong></p>

<pre><code>from __future__ import unicode_literals
from django.db import models
class bank_table(models.Model):
    bank_ac_num=models.IntegerField(primary_key=True,unique=True)
    bank_ifci_code=models.CharField(max_length=30)
    user_status=models.IntegerField(max_length=1,default=1)
class wallet_table(models.Model):
    mob_num=models.IntegerField(primary_key=True,max_length=10,unique=True)
    bank_ac_num=models.ForeignKey(bank_table,null=True)    
    wallet_amnt=models.IntegerField(default=0)
class user_table(models.Model):
    user_id=models.IntegerField(primary_key=True,unique=True)
    user_name=models.CharField(max_length=30)
    mob_num=models.ForeignKey(wallet_table,null=True)
</code></pre>

<p>Whole project file available  <a href="https://drive.google.com/open?id=0B0DlE-Qi4Fu6b0RDM2ZvOVFVQlU" rel="nofollow">here</a></p>

<p>Thanks in advance.</p>