Built models, such as Author and Books, for the bookshelf app

elaizabolislis_reading/bookshelf/models.py

 from django.db import models
+from django.core.validators import MaxValueValidator, MinValueValidator
+import datetime
 
-# Create your models here.
+
+class Author(models.Model):
+    first_name = models.CharField(max_length=255)
+    last_name = models.CharField(max_length=255)
+    age = models.IntegerField()
+    nationality = models.CharField(max_length=255)
+    bio = models.TextField(max_length=700)
+
+    def __str__(self):
+        return '{} {}'.format(self.first_name, self.last_name)
+
+
+class Books(models.Model):
+    title = models.CharField(max_length=255)
+    author = models.ForeignKey(Author, on_delete=models.CASCADE)
+    publisher = models.CharField(max_length=150)
+    YEAR_PUBLISHED_CHOICES = [
+        (r, r)for r in range(1000, datetime.date.today().year+1)
+    ]
+    year_published = models.PositiveIntegerField(
+        choices=YEAR_PUBLISHED_CHOICES,
+        default=datetime.date.today().year
+    )
+    ISBN = models.PositiveIntegerField(validators=[
+        MaxValueValidator(9999999999999),
+        MinValueValidator(1000000000000)],
+        default=1000000000000
+    )
+    blurb = models.TextField(max_length=1000)
+
+    def __str__(self):
+        return '{} ({}) by {}'.format(self.title, self.year_published, self.author)