Payload

Payload is the data sent by triggers as input and is accessible from the context object. Currently there are two payload types:

• HTTP request body
• MQ message

Availability

• ✓ Generic logic
• ✓ Aggregator logic

info

Since the payload type depends on triggers, developers using a TypeScript template in CLI must use a type guard to ensure type safety in the compiling process:

let data: number[] = [];

if ("http" in ctx.payload) {
    // check if it's HTTP payload
    data = ctx.payload.http.body;
} else if ("messageQueue" in ctx.payload) {
    // check if it's MQ payload
    data = ctx.payload.messageQueue.data;
} else {
    // if none of above, throw an error
    throw new Error("this logic only accepts http/mq payload");
}

// data will be the payload content

HTTP Payload

ctx.payload.http (type: HttpPayload)

Member	Type	Description	Example
apiGatewayIdentityContext	DataSourceIdentityContext, which is { id: string, name: string }	API gateway permanent ID and name
apiIdentityContext	DataSourceIdentityContext	API route permanent ID and name
requestId	string	Request ID
host	string	Request host name
path	string	API route	/path/subpath
scheme	string	HTTP scheme	http or https
method	string	HTTP method	GET, POST, etc.
version	"HTTP/0.9" | "HTTP/1.0" | "HTTP/1.1" | "HTTP/2.0" | "HTTP/3.0"	HTTP version
headers	{ [k: string]: unknown; }	Request headers	{ "content-type": "application/json" }
query	string	URL query string	param1=value1 (no question mark)
body	number[]	Request body

Example: read API route and headers

const path = ctx.payload.http.path;
const headers = ctx.payload.http.headers;
const contentType = headers["content-type"];

Example: parsing GET querystring

// assume the querystring is ?name=<name>&age=<age>

const query = ctx.payload.http.query;

const searchParams = new URLSearchParams(query);

// access parsed fields (return null if not exist)
const name = searchParams.get("name");
const age = searchParams.get("age");

Example: parsing POST JSON body

// assume the payload is { "name": <name>, "age": <age> }

const body = new TextDecoder().decode(new Uint8Array(ctx.payload.http.body));

const parsed = JSON.parse(body);

// access parsed fields using optional chaining (return undefined if not exist)
const name = parsed?.name;
const age = parsed?.age;

Message Queue Payload

ctx.payload.messageQueue (type: MessageQueuePayload)

Member	Type	Description
clientIdentityContext	DataSourceIdentityContext, see HTTP payload	MQ client permanent ID and name
data	number[]	MQ data
subscriber	Subscriber	MQ subscriber

Subscriber type members describe the message queue sources:

Apache Kafka

• Subscriber type: KafkaSubscriber

Member	Type	Description
brokers	string[]	Broker names in the Kafka cluster
groupId	string	MQ group ID
topic	string	MQ topic
partition	number	MQ partition
offset	number	MQ offset

tip

Supports for other message queues are on the way!