Amplify Transformers

A collection of useful transformers for your GraphQL schema

Installation

Install with npm install --save @halftome/amplify-transformers

Usage

Setup Custom Transformers

Edit amplify/backend/api/<YOUR_API>/transform.conf.json and append the following:

"transformers": [
  "@halftome/amplify-transformers/dist/PipelineTransformer",
  "@halftome/amplify-transformers/dist/DynamoDBTransformer"
]

DynamoDB

Use the @dynamodb directive to attach a DynamoDB resolver to your field.

Example:

type Foo @model {
  id: ID!
  name: String!
}

type Query {
  fooBar: Foo @dynamodb(table: "Foo")
}

The default templates will be Query.fooBar.req.vtl and Query.fooBar.res.vtl generated from the type and the field. If they don't exist, they will be generated, but you need to change the content of the request mapping template.

Pipeline

Use the @pipeline directive to attach a Pipeline resolver to your field. This will just create an empty pipeline. To add functions to the pipeline, use the other directives.

Example:

type Foo @model {
  id: ID!
  name: String!
}

type Baz @model {
  id: ID!
  name: String!
}

type Query {
  fooBarBaz: FooBaz
    @pipeline
    @dynamodb(table: "Foo", name: "GetFoo")
    @dynamodb(table: "Baz", name: "GetBaz")
}

This will create a pipeline which executes two dynamodb resolvers one after another. First Foo, then Baz. Their request mapping templates are in the pipelineFunctions directory, and need to be overriden to do anything useful.

Known Issues / Gotchas

When chaining directives, their order is not necessarily in the order they are written in GraphQL. See this issue for details: https://github.com/aws-amplify/amplify-cli/issues/6176 This is why its important to have the pipeline transformer defined first in transform.conf.json. Hopefully this will be fixed soon, and it will allow us to use the @function directive with the @pipeline