CODEWITHSUNDEEP
pythonmysqldjango
Kirtiraj Botre
Kirtiraj Botre

Reputation: 3

__str__ returned non-string (type NoneType) django

I'm trying to take input the person table but I'm getting this error. I have connect these two models and I'm returning the string to connect it can anyone tell me solution for this below are my codes

this code is from models.py

from django.db import models

class Person(models.Model):
    PersonID=models.CharField(max_length=30,null=True)
    Lastname=models.CharField(max_length=30,null=True)
    Middlename=models.CharField(max_length=30,null=True)
    Firstname=models.CharField(max_length=30,null=True)
    Initials=models.CharField(max_length=10,null=True)
    Title=models.CharField(max_length=10,null=True)
    Gender=models.CharField(max_length=10,null=True)
    Birthdate=models.DateField(default=None,null=True)

    def __str__(self):
       return self.PersonID
    
    


class Function(models.Model):
    FunctionCode=models.CharField(max_length=30,null=True)
    FunctionName=models.CharField(max_length=30,null=True)
    MinSalary=models.IntegerField(null=True)
    MaxSalary=models.IntegerField(null=True)
    DefaultBillingRate=models.CharField(max_length=30,null=True)

    def __str__(self):
       return self.FunctionCode

this code is from forms

from django.forms import ModelForm
from .models import Person

class PersonForm(ModelForm):
    class Meta:
        model = Person
        fields = '__all__'

this code is from views

from django.shortcuts import render
from .forms import Person
from .models import *


def createPerson(request):
    form = Person()

    context = {'form':form}
    return render(request, 'create_person.html', context )

this code is from person.html

{% extends 'main.html' %}
{% load static %}
{% block content %}

<form action="" method="POST">
    {% csrf_token %}
    {{form}}
    
    <input type="submit" name="Submit">
</form>


{% endblock %}

Upvotes: 0

Views: 1063

Answers (3)

Alexander Yudkin
Alexander Yudkin

Reputation: 472

If field could be None (null=True), then the __str__ method can return None. You should prevent this:

def __str__(self):
    return self.field or ''

It returns the field's value if it is not None, otherwise it returns an empty string.

Upvotes: 1

Torcat
Torcat

Reputation: 51

In both models the fields returned by the str method can be null, you must establish a condition.

Example: Model -> Person

  def __str__(self):
    if self.PersonID is not None:
      return self.PersonID
    return "Custom String"

Model -> Function

  def __str__(self):
    if self.FunctionCode is not None:
      return self.FunctionCode
    return "Custom String"

Upvotes: 0

Mojtaba Arezoomand
Mojtaba Arezoomand

Reputation: 2380

As you can see your FunctionCode can be null.
your __str__ method should only return string, but when FunctionCode is null it will return None instead of string.
You can return a non nullable field or you can do this.

def __str__(self):
    if self.FunctionCode is not None:
        return self.FunctionCode
    return "Unknown"

Upvotes: 1

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