AppSync的S3Object GraphQL类型是否绑定DynamoDB？能否用于Lambda数据源？

Hey there! Let's break down your questions clearly and directly:

1. Is the AppSync S3Object GraphQL type tied to DynamoDB? #

Absolutely not. The S3Object type shown in the docs is just a custom GraphQL object type designed to represent the location of an object in S3 (via bucket, key, and region fields). The DynamoDB example in the docs is just a common use case—this type has no hard dependency on DynamoDB at all. Think of it as a standardized way to pass around S3 object metadata in your schema, nothing more.

2. Can it be used with a Lambda data source (e.g., one connected to MongoDB)? #

100% yes! Here's how it works in practice:

• Keep your S3Object type in your GraphQL schema exactly as you've defined it.
• When setting up your Lambda resolver (for queries/mutations that fetch or return a Post with the file field), your Lambda just needs to return data that matches the S3Object shape.
• For example, if your MongoDB documents store S3 metadata (like s3_bucket, s3_key, s3_region), your Lambda can pull those values, map them to the bucket, key, region fields of S3Object, and include that in the response.

Quick Lambda code snippet example (Node.js): #

// Lambda function connected to MongoDB
exports.handler = async (event) => {
  // Fetch post data from MongoDB (pseudo-code)
  const postFromMongo = await mongodb.collection('posts').findOne({ id: event.arguments.id });
  
  // Map MongoDB fields to your GraphQL Post type, including S3Object
  return {
    id: postFromMongo._id.toString(),
    author: postFromMongo.author,
    title: postFromMongo.title,
    // ... other Post fields
    file: {
      bucket: postFromMongo.s3_bucket,
      key: postFromMongo.s3_key,
      region: postFromMongo.s3_region
    },
    version: postFromMongo.version
  };
};

AppSync will automatically validate that the Lambda's response matches your schema, including the S3Object structure. As long as your Lambda returns the correct shape, everything works smoothly.

内容的提问来源于stack exchange，提问作者honkskillet