models.py

from django.db import models

class Topic(models.Model):
    #a class to save text and time

    text = models.CharField(max_length=200)
    date_added = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.text

class Entry(models.Model):

    topic = models.ForeignKey(Topic,on_delete=models.CASCADE)
    text = models.TextField()
    date_added = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name_plural = 'Entries'

    def __str__(self):

        if len(self.text)>50:

            return f"{self.text[:50]}....."

        else:
            return self.text