Scalar types in GraphQL

A GraphQL object type has a name and fields, and those fields can have sub-fields. Ultimately, an object type's fields must resolve to scalar types, which represent the leaves of the query. For more information about object types and scalars, see Schemas and types on the GraphQL website.

In addition to the default set of GraphQL scalars, AWS AppSync also lets you use the service-defined scalars that start with the AWS prefix. AWS AppSync doesn't support the creation of user-defined (custom) scalars. You must use either the default or AWS scalars.

You cannot use AWS as a prefix for custom object types.

The following section is a reference for schema typing.

Default scalars

GraphQL defines the following default scalars:

AWS AppSync scalars

AWS AppSync defines the following scalars:

Schema usage example

The following example GraphQL schema uses all of the custom scalars as an "object" and shows the resolver request and response templates for basic put, get, and list operations. Finally, the example shows how you can use this when running queries and mutations.

type Mutation {
    putObject(
        email: AWSEmail,
        json: AWSJSON,
        date: AWSDate,
        time: AWSTime,
        datetime: AWSDateTime,
        timestamp: AWSTimestamp,
        url: AWSURL,
        phoneno: AWSPhone,
        ip: AWSIPAddress
    ): Object
}

type Object {
    id: ID!
    email: AWSEmail
    json: AWSJSON
    date: AWSDate
    time: AWSTime
    datetime: AWSDateTime
    timestamp: AWSTimestamp
    url: AWSURL
    phoneno: AWSPhone
    ip: AWSIPAddress
}

type Query {
    getObject(id: ID!): Object
    listObjects: [Object]
}

schema {
    query: Query
    mutation: Mutation
}

Here's what a request template for putObject might look like. A putObject uses a PutItem operation to create or update an item in your Amazon DynamoDB table. Note that this code snippet doesn't have a configured Amazon DynamoDB table as a data source. This is being used as an example only:

{
    "version" : "2017-02-28",
    "operation" : "PutItem",
    "key" : {
        "id": $util.dynamodb.toDynamoDBJson($util.autoId()),
    },
    "attributeValues" : $util.dynamodb.toMapValuesJson($ctx.args)
}

The response template for putObject returns the results:

$util.toJson($ctx.result)

Here's what a request template for getObject might look like. A getObject uses a GetItem operation to return a set of attributes for the item given the primary key. Note that this code snippet doesn't have a configured Amazon DynamoDB table as a data source. This is being used as an example only:

{
    "version": "2017-02-28",
    "operation": "GetItem",
    "key": {
        "id": $util.dynamodb.toDynamoDBJson($ctx.args.id),
    }
}

The response template for getObject returns the results:

$util.toJson($ctx.result)

Here's what a request template for listObjects might look like. A listObjects uses a Scan operation to return one or more items and attributes. Note that this code snippet doesn't have a configured Amazon DynamoDB table as a data source. This is being used as an example only:

{
    "version" : "2017-02-28",
    "operation" : "Scan",
}

The response template for listObjects returns the results:

$util.toJson($ctx.result.items)

The following are some examples of using this schema with GraphQL queries:

mutation CreateObject {
    putObject(email: "[email protected]"
        json: "{\"a\":1, \"b\":3, \"string\": 234}"
        date: "1970-01-01Z"
        time: "12:00:34."
        datetime: "1930-01-01T16:00:00-07:00"
        timestamp: -123123
        url:"https://amazon.com"
        phoneno: "+1 555 764 4377"
        ip: "127.0.0.1/8"
    ) {
        id
        email
        json
        date
        time
        datetime
        url
        timestamp
        phoneno
        ip
    }
}

query getObject {
    getObject(id:"0d97daf0-48e6-4ffc-8d48-0537e8a843d2"){
        email
        url
        timestamp
        phoneno
        ip
    }
}

query listObjects {
    listObjects {
        json
        date
        time
        datetime
    }
}