Mapping S3 bucket object's audio metadata to DynamoDB - reactjs

Question

Let's say I have imported a large number of audio files in S3. I would need to map my audio files metadata (including artist, track name, duration, release date, ...) to a DynamoDB table in order to query them using a GraphQL API in a react app. However, I can't yet figure out how to extract these metadata to be mapped in DynamoDB.
In the DynamoDB developer guide, it is mentioned (p.914) that the S3 object identifier can be stored in the DynamoDB item.
It is also mentioned that S3 object metadata support can provide a link back to the parent item in DynamoDB (by storing the primary key value of the table item as the S3 metadata).
However, the process is not really detailed; the closest approach I found is from J. Beswick who uses a lambda function to load a large amount of data from a JSON file stored in an S3 bucket.
(https://www.youtube.com/watch?v=f0sE_dNrimU&feature=emb_logo).

Answer 1

S3 object metadata is something different from audio metadata.
Think this way: everything that you put on S3 is a object. This object has a key (name) and some metadata attached to it by default by S3 and another metadata that you can attach to it. All of these things are explained here.
Audio files metadata are a different thing. They are inside the file (let's suppose that it is a mp3 file). To access this data you need to read the file using a api that knows the file format and how to extract the data.
When you upload the file to s3 it does not extract any kind of data and attach it to your object metadata (artist, track number, etc from mp3 files). You need to do it by yourself.
A suggested solution would be: for every file that you upload to s3, the upload triggers a lambda function that knows how to extract the audio metadata from the file. It will then extract this metadata and save it on DynamoDB together with the name of the object in s3. After that you can query your table with the search that you planned for and after found the record, point to the correct object in s3.
In that suggestion you can also run it for all objects already existent in the s3 bucket to avoid requiring new upload.