did some minor changes in the models and populated the database

sharmchua_reading/bookshelf/admin.py

 from django.contrib import admin
 
-from .models import Author, Book
+from .models import Author, Books
 
 class AuthorAdmin(admin.ModelAdmin):
     model = Author
@@ -9,10 +9,10 @@ class AuthorAdmin(admin.ModelAdmin):
     list_filter = ('first_name', 'last_name', 'age', 'nationality',)
 
 class BooksAdmin(admin.ModelAdmin):
-    model = Book
+    model = Books
     list_display = ('title', 'author', 'publisher', 'year_published', 'ISBN', 'blurb',)
     search_fields = ('title', 'author', 'publisher', 'year_published', 'ISBN',)
     list_filter = ('title', 'author', 'publisher', 'year_published',)
 
 admin.site.register(Author, AuthorAdmin)
-admin.site.register(Book, BooksAdmin)
+admin.site.register(Books, BooksAdmin)

sharmchua_reading/bookshelf/migrations/0003_alter_author_nationality.py

+# Generated by Django 3.2 on 2023-03-28 11:40
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('bookshelf', '0002_rename_books_book'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='author',
+            name='nationality',
+            field=models.CharField(default='', max_length=50),
+        ),
+    ]

sharmchua_reading/bookshelf/migrations/0004_rename_book_books.py

+# Generated by Django 4.1.6 on 2023-03-28 11:57
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('bookshelf', '0003_alter_author_nationality'),
+    ]
+
+    operations = [
+        migrations.RenameModel(
+            old_name='Book',
+            new_name='Books',
+        ),
+    ]

sharmchua_reading/bookshelf/migrations/0005_alter_books_isbn.py

+# Generated by Django 4.1.6 on 2023-03-28 12:18
+
+import bookshelf.models
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('bookshelf', '0004_rename_book_books'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='books',
+            name='ISBN',
+            field=models.IntegerField(default=0, unique=True, validators=[bookshelf.models.validate_isbn]),
+        ),
+    ]

sharmchua_reading/bookshelf/models.py

@@ -9,18 +9,18 @@ class Author(models.Model):
     first_name = models.CharField(max_length=100,default="")
     last_name = models.CharField(max_length=100,default="")
     age = models.IntegerField(default=0)
-    nationality = models.CharField(max_length=50,unique=True,default="")
+    nationality = models.CharField(max_length=50,default="")
     bio = models.TextField(max_length=700,default="")
 
     def __str__(self):
         return '{} {}'.format(self.first_name, self.last_name)
 
-class Book(models.Model):
+class Books(models.Model):
     title = models.CharField(max_length=50,default="")
     author = models.ForeignKey(Author,on_delete=models.CASCADE)
     publisher = models.CharField(max_length=100,default="")
     year_published = models.IntegerField(default=2023)
-    ISBN = models.IntegerField(validators=[validate_isbn],default=0000000000000)
+    ISBN = models.IntegerField(validators=[validate_isbn],unique=True,default=0000000000000)
     blurb = models.TextField(max_length=200,default="")
 
     def __str__(self):