Quick AWS AppSync

Posted on October 2, 2021

Tags: aws

1 Summary

GraphQL schema similar to interface or type-signature
pipelineResolver similar to concrete implementation of interface

2 Schema

type Picture {
	id: ID!
	owner: ID!
	src: String
}

type Query {
	myCustomQuery(id: ID!): [Picture]
		@aws_auth(cognito_groups: ["Admins","Viewers"])
}

schema {
	query: Query
}

3 Attach dynamoDB

Click “Create Resources”
- Use existing type >> “Picture”

input CreatePictureInput {
	owner: ID!
	src: String
}

input DeletePictureInput {
	id: ID!
}

type Mutation {
	createPicture(input: CreatePictureInput!): Picture
	updatePicture(input: UpdatePictureInput!): Picture
	deletePicture(input: DeletePictureInput!): Picture
}

type Picture {
	id: ID!
	owner: ID!
	src: String
}

type PictureConnection {
	items: [Picture]
	nextToken: String
}

type Query {
	myCustomQuery(id: ID!): [Picture]
		@aws_auth(cognito_groups: ["Admins","Viewers"])
	getPicture(id: ID!): Picture
	listPictures(filter: TablePictureFilterInput, limit: Int, nextToken: String): PictureConnection
}

type Subscription {
	onCreatePicture(id: ID, owner: ID, src: String): Picture
		@aws_subscribe(mutations: ["createPicture"])
	onUpdatePicture(id: ID, owner: ID, src: String): Picture
		@aws_subscribe(mutations: ["updatePicture"])
	onDeletePicture(id: ID, owner: ID, src: String): Picture
		@aws_subscribe(mutations: ["deletePicture"])
}

input TableBooleanFilterInput {
	ne: Boolean
	eq: Boolean
}

input TableFloatFilterInput {
	ne: Float
	eq: Float
	le: Float
	lt: Float
	ge: Float
	gt: Float
	contains: Float
	notContains: Float
	between: [Float]
}

input TableIDFilterInput {
	ne: ID
	eq: ID
	le: ID
	lt: ID
	ge: ID
	gt: ID
	contains: ID
	notContains: ID
	between: [ID]
	beginsWith: ID
}

input TableIntFilterInput {
	ne: Int
	eq: Int
	le: Int
	lt: Int
	ge: Int
	gt: Int
	contains: Int
	notContains: Int
	between: [Int]
}

input TablePictureFilterInput {
	id: TableIDFilterInput
	owner: TableIDFilterInput
	src: TableStringFilterInput
}

input TableStringFilterInput {
	ne: String
	eq: String
	le: String
	lt: String
	ge: String
	gt: String
	contains: String
	notContains: String
	between: [String]
	beginsWith: String
}

input UpdatePictureInput {
	id: ID!
	owner: ID
	src: String
}

schema {
	query: Query
	mutation: Mutation
	subscription: Subscription
}

Analysis AppSync autogeneration:
- Basically builds CRUD with
  - CUD with Mutation/Subscription type
  - R with Query type
- type Mutations contains CREATE, UPDATE, DELETE and and their respective input types
  - createPicture(input: CreatePictureInput!): Picture
  - type CreatePictureInput {..}
- type Query contains READ in the forms of read 1 element or read list of elements
  - getPicture(id: ID!): Picture
  - listPictures(filter: TablePictureFilterInput, limit: Int, nextToken: String): PictureConnection
    - type PictureConnection contains nextToken and [Picture]
      - nextToken is alot like redis SCAN’s Last Searched Index,
      - listPictures will only return a partial list, and the nextToken is the index of the next partial list until nextToken is null
    - type TablePictureFilterInput contains Table____FilterInput

4 AppSync Query builder UI

Input is boxed in green
Output is boxed in orange
Query builder is boxed in brown
Query result is the far right sidebar

NOTICE: Even though owner*: hi is used for Input, the Query result does not show any owner results. That is because we did not include owner in the output boxed in orange.