This error is raised by django-parler when I'm trying to add a new Book using django admin interface.
models.py
from django.db import models
from django.urls import reverse
from isbn_field import ISBNField
from django.core.validators import MinValueValidator
from parler.models import TranslatableModel, TranslatedFields
class Genre(TranslatableModel):
translations = TranslatedFields(
title=models.CharField(max_length=200,
db_index=True),
slug=models.SlugField(max_length=200,
db_index=True,
unique=True,
help_text='Unique value for book page URL, created from name.'),
description=models.TextField(blank=True, db_index=True),
)
class Meta:
db_table = 'genres'
verbose_name_plural = 'Genres'
def __str__(self):
return self.title
def get_absolute_url(self):
return reverse('bookstore:book_list_by_genre',
args=[self.slug])
class Book(TranslatableModel):
translations = TranslatedFields(
title=models.CharField(max_length=200,
db_index=True),
slug=models.SlugField(max_length=200,
db_index=True,
unique=True),
author=models.CharField(max_length=100,
db_index=True,
blank=True,
null=True,
default=None),
edition_language=models.CharField(max_length=100,
db_index=True,
blank=True,
null=True,
default=None),
description=models.TextField(blank=True,
db_index=True),
binding=models.CharField(max_length=100,
db_index=True,
blank=True,
null=True,
default=None),
)
genres = models.ManyToManyField(Genre, related_name='books',
default=None,
blank=True)
isbn = ISBNField(unique=True,
blank=True,
null=True,
help_text='ISBN is a ten or thirteen digit number used to '
'identify books and book-like resources.')
price = models.DecimalField(max_digits=9, decimal_places=2, default=0.00, validators=[MinValueValidator(0.00)])
old_price = models.DecimalField(max_digits=9, decimal_places=2, default=0.00, validators=[MinValueValidator(0.00)])
discount = models.DecimalField(max_digits=4, decimal_places=2, default=0, max_length=4)
quantity = models.PositiveIntegerField(validators=[MinValueValidator(1)])
publisher = models.CharField(max_length=100, blank=True, null=True, default=None)
pub_year = models.CharField(max_length=4, blank=True, null=True, default=None)
bestseller = models.BooleanField(default=False)
available = models.BooleanField(default=True)
created = models.DateTimeField(auto_now_add=True)
updated = models.DateTimeField(auto_now=True)
class Meta:
db_table = 'books'
ordering = ['-created']
def __str__(self):
return self.title
def save(self, *args, **kwargs):
if self.discount == 0 and self.old_price >= self.price:
self.price = self.old_price
if self.discount != 0:
self.old_price = self.price
# calculate discount
self.price = self.price * (100 - self.discount) / 100
super(Book, self).save(*args, **kwargs)
def get_absolute_url(self):
return reverse('bookstore:book_detail',
args=[self.id, self.slug])
class BookImage(models.Model):
book = models.OneToOneField(Book, on_delete=models.CASCADE, blank=True, null=True, default=None)
image = models.ImageField(upload_to='img/books/%Y/%m/%d', blank=True, null=True, default=None, unique=True)
created = models.DateTimeField(auto_now_add=True, auto_now=False)
updated = models.DateTimeField(auto_now_add=False, auto_now=True)
def __str__(self):
return str(self.id)
class Meta:
db_table = 'images'
verbose_name = 'Book Image'
verbose_name_plural = 'Book Images'
admin.py
from django.contrib import admin
from .models import *
from parler.admin import TranslatableAdmin, TranslatableStackedInline
class BookImageInline(TranslatableStackedInline):
model = BookImage
max_num = 1
# set limit for extra entries
extra = 0
@admin.register(Genre)
class GenreAdmin(TranslatableAdmin):
# set up fields ordering
list_display = ['title', 'slug']
# set up admin search fields
search_fields = ['title', 'description']
def get_prepopulated_fields(self, request, obj=None):
return {'slug': ('title',)}
@admin.register(Book)
class BookAdmin(TranslatableAdmin):
list_display = ['title', 'slug', 'price',
'available', 'created', 'updated']
list_filter = ['available', 'created', 'updated']
list_editable = ['price', 'available']
inlines = [BookImageInline]
def get_prepopulated_fields(self, request, obj=None):
return {'slug': ('title',)}
@admin.register(BookImage)
class BookImageAdmin(admin.ModelAdmin):
list_display = ('book', 'created', 'updated',)
list_filter = ('book',)
class Meta:
model = BookImage
BookImageInline must not be translatable as the underlying model BookImage is not translatable:
class BookImageInline(StackedInline): # not TranslatableStackedInline
# ...
Whether the model (Book in your case) that integrates this Inline is translatable or not, is irrelevant to the choice of inline type.