[Apollo] Support AWS AppSync custom scalars

[mattcreaser]

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• I have searched for duplicate or closed issues and discussions.

Language and Async Model

Kotlin, Kotlin - Coroutines

Amplify Categories

Not applicable

Gradle script dependencies

n/a

Environment information

n/a

Please include any relevant guides or documentation you're referencing

https://docs.aws.amazon.com/appsync/latest/devguide/scalars.html

Describe the feature request

By default, when using Apollo Kotlin with the Amplify Apollo Extensions, all of the custom scalars in AppSync get generated as Any type. This makes it awkward to use e.g. the createdAt field in a generated Apollo model.

In the actual returned data the Any field can be cast to a String (its actual type) and then parsed into e.g. an Instant, but this is sub-optimal for many reasons. Ideally the scalar GraphQL type AWSDateTime would already be converted into a platform-appropriate type.

This can be done in Apollo by defining adapters for Custom Scalars.

This issue covers adding support for the AWS-specific Scalars present in AppSync schemas to the extensions library.

Ideally this would include any necessary runtime classes, Apollo adapter implementations, and instructions on how to configure the Apollo Gradle Plugin.

Initialization steps (if applicable)

No response

Code Snippet

n/a

amplifyconfiguration.json

No response

GraphQL Schema

n/a

Additional information and screenshots

No response

[github-actions]

This issue was opened by a maintainer of this repository; updates will be posted here. If you are also experiencing this issue, please comment here with any relevant information so that we're aware and can prioritize accordingly.