关于DRF序列化器中many与source字段的理解求助

Hey there! Let's walk through exactly what these two parameters are doing in your code—they're super common when working with related models in DRF, so this is a great question.

First, let's talk about source='answer_set' #

In Django, when you set up a one-to-many relationship (like your Question and Answer models, where each Question has multiple Answers), Django automatically creates a reverse relationship on the parent model. By default, this reverse relationship is named [child_model_name]_set—so for your Answer model linked to Question, that's answer_set.

The source parameter here tells DRF:

"Instead of looking for an attribute named answers on the Question instance, use the answer_set attribute instead, and serialize that value."

This lets you rename the field to something cleaner (like answers) in your API response, even though the underlying Django attribute is answer_set—way more user-friendly for front-end developers consuming your API!

Next, many=True #

Since a single Question can have multiple Answers, the answer_set attribute is a QuerySet (a collection of multiple Answer objects), not a single instance.

The many=True flag tells DRF:

"This field represents a collection of objects, not just one. Use the embedded serializer (EmbeddedAnswerSerializer) to serialize each object in the collection, and return them as an array."

If you left out many=True, DRF would try to serialize answer_set as a single Answer instance, which would throw an error—because you're passing a list/QuerySet where it expects a single object.

Putting it all together in your code #

Your QuestionSerializer is doing two key things:

• Pulling all related Answer instances via the answer_set reverse relationship
• Serializing each of those answers with EmbeddedAnswerSerializer, then packaging them into an array under the answers key in your API response

So when you serialize a Question, your API response will look something like this (simplified):

{
  "id": 1,
  "answers": [
    {"id": 1, "text": "First answer", "votes": 5},
    {"id": 2, "text": "Second answer", "votes": 2}
  ],
  "created_at": "2024-01-01T00:00:00Z",
  "text": "What's DRF?",
  "user_id": 123
}

内容的提问来源于stack exchange，提问作者MistyD