Using an exisiting AppSync API w/ Amplify - amazon-web-services

Question

Using:
AppSync, DynamoDB, and Lambda
So I am a bit stuck on how to integrate AppSync within Amplify in React Native. I have an existing API within AWS AppSync that I created on the console. This API has several different models like: Users, Videos, VideoComments, etc. Some of the objects within these models have custom mapping templates and resolvers that are really important for the application.
For Example, this is a quick look at what we have schema wise.
type User {
userId: Id!
name: String
uploadedVideos(limit: Int, nextToken: String): VideoConnection
etc etc
}
type Video {
videoID: Id!
object: S3Object
userId: Id!
uploadedBy: User
}
We have a resolver that runs with a simple getVideo query that will retrieve the uploadedBy attribute by using the userId, and retrieves all the necessary information of that user.
Additionally, the data sources (dynamoDb tables) we created for the models have primary keys, and some have sort keys. Like a VideoLikes table keeps track of who liked a video and to avoid duplicates the primary key is the VideoID and the sort key is UserID. This is just a minor example, we have other places where we do this to also have access to LSIs.
When I started using Amplify, I tried recreating the AppSync API because I liked how powerful the CloudFormation capabilities were with the different staging environments. However, I noticed the DynamoDB for models were automatically defined and were automatically set to an id as a primary key. We use the LSIs to help sort by certain values, like for a video if we wanted to sort by the number of likes, or comments, so unfortunately this would not work for us. So when I noticed this, I used the "Codegen" command from my original AppSync API and ran into the issue where my resolvers and mapping templates were not copied down with the schema, queries, mutations, and subscriptions making most of the queries fail because those data sources were missing.
So my question is:
Is there a way to integrate/use EVERYTHING from my exiting AppSync API within my React Native application? This includes the custom resolvers and mapping templates.
IF NOT
Is there a way to set a primary and sort key for the DynamoDB of the Models when creating an API directly within the Amplify CLI?
IF NOT
Is there another way to have data sorted efficiently within DynamoDB without using LSIs and GSIs? If the models automatically generate tables with GSIs, this can be problematic because I know GSIs are a bit more expensive so I would like to avoid those as much as possible. Is there another service that will sort the data that can be used within AppSync from DynamoDB?
Any help will be appreciated, thank you.

Answer 1

Is there a way to integrate/use EVERYTHING from my exiting AppSync API within my React Native application?
Yes, you can deploy your API however you want and then use it using amplify client tools. You can always use the Ampify CLI's codegen features without deploying the API via the amplify api category. You can use custom stacks to define custom resolvers that are not generated by #model but this will deploy a new API with the same structure as your existing API.
Is there a way to set a primary and sort key for the DynamoDB of the Models when creating an API directly within the Amplify CLI?
Soon. There is an RFC here https://github.com/aws-amplify/amplify-cli/issues/1062 and implementation is in PR here https://github.com/aws-amplify/amplify-cli/pull/1463.
Is there another way to have data sorted efficiently within DynamoDB without using LSIs and GSIs?
No but you can use index overloading to make 1 index store and sort multiple different conceptual object types. TBH this is a complex subject but here is a good place to start https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-gsi-overloading.html.