DataStore codegen changes for upcoming iOS release

[drochetti]

Description

When generating code for GraphQL schemas on iOS, some features are missing, such as enum and non-model types. This ticket highlights the required changes for the upcoming iOS release of Amplify DataStore.

Enums:

Given the GraphQL schema:

enum PostStatus {
    active
    inactive
    draft
}

The expected iOS code is:

import Amplify

public enum PostStatus: String, EnumPersistable {

    case active
    case inactive
    case draft

}

Notes:

• Enum values in Swift should be camelCase
• The protocol being added (EnumPersistable)
• Some enum values might clash with reserved keywords in Swift, in that case it needs to be escaped. To escape in Swift use back-ticks: `public`
• it's not necessary to register Enums in the ModelRegistry

Non-model types (aka Nested or Embedded types)

For non-model types, the codegen should generate Swift structs that follow the same semantic of the model types minus the Model-specific rules such as : Model and using List<M> for associations (since associations are not supported in non-model types).

type Location {
    latitude: Float!
    longitude: Float!
    tags: [String]
}

The expected iOS code is:

public struct Location: Codable {

    var latitude: Double
    var longitude: Double
    var tags: [String]

}

Notes:

• reuse all the types from models but:
  • doesn't conform to Model
  • conforms to Codable
• never use List<M>
• models cannot be used as property types of non-model types (I believe this is enforced at the transformer level already, is that correct?)

Schema definition

On the schema definition (e.g. Post+Schema.swift) when dealing with non-model types and arrays of non-model/scalar types the definition should be like:

.customType(Location.self)
.customType([String].self)

// complete definition of a field:

.field(example.nonModelField, is: .required, ofType: .customType(ExampleNonModelType.self))

// .collection(of) is only used for Model types
.field(example.arrayOfStringsField, is: .required, ofType: .customType([String].self))

Related issues:

• codegen fails to generate code for non @model dependencies  amplify-swift#240
  • Codegen failure: Enum types generates an invalid type definition as enums do not implement Codable amplify-swift#246
  • Modelgen generates non-codeable model amplify-swift#257
• Support enums in code generated models amplify-swift#111

Edit: added information about how to define the schema for the non-model types

Edit 2:

• final name for the enum protocol: EnumPersistable
• final name for non-model types and arrays of scalars/types: .customType (code samples above updated accordingly)

[drochetti]

The iOS PR aws-amplify/amplify-swift#334 landed in master. The names were updated in the original issue and reflect the final names.

[yuth]

Change have been released in Amplify CLI v 4.17.2

[github-actions]

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