title: Concatenate a specific field from child objects into parent object?
body: <p>I have two models:</p>
  <pre><code>class Chapter(models.Model):
      chapter = models.IntegerField()
      verses_amount = models.IntegerField()
      chapter_content = models.TextField()
      
  
  class Verse(models.Model):
      chapter = models.ForeignKey(Chapter, on_delete=CASCADE)
      verse = models.TextField()
      verse_number = models.IntegerField()
  </code></pre>
  <p>On <code>Verse</code>, I store a paragraph in the <code>verse</code> field.
  How can I query all children (<code>Verse</code>), get their <code>verse</code> paragraph, concatenate all those and put that in <code>Chapter.chapter_content</code>?</p>
  <p>Eg</p>
  <pre><code>verses = Verse.objects.filter()[0:2]
  for verse in verses:
      print(verse.verse)
  
  &gt;&gt; 'Lorem Ipsum.'
  &gt;&gt; 'Second Lorem Ipsum Iteration 2.'
  </code></pre>
  <p>In the parent <code>Chapter</code>, I want <code>chapter_content</code> to hold the two values as one long string:</p>
  <p>'Lorem Ipsum. Second Lorem Ipsum Iteration 2.'</p>