bs-aws-lambda
is a set of types to use when creating AWS
lambda handlers.
Those types are inspired by the
@types/aws-lambda
package with typescript types.
yarn add @ahrefs/bs-aws-lambda
or to follow the master version:
yarn add https://github.com/ahrefs/bs-aws-lambda.git
Add @ahrefs/bs-aws-lambda
to the bs-dependencies
of bsconfig.json
.
Then when you create a function handler for a lambda, you can annotate
it with one of AwsLambda.Scheduled.handler
,
AwsLambda.Dynamodb.streamHandler
, AwsLambda.Sns.handler
, etc. This
way you are sure to expose a function which respect the signature
expected by Lambda and you get types information for all the
parameters this function will receive.
A full example is documented
here. It
is using the sources from the example
directory.
Simple echo function for the API Gateway. This might seem a little verbose compare to a typescript version. But using this package, you are sure to handle all the possible cases where a value is actually null or base64 encoded. Plus the returned object given to the callback will always have the expected fields and types.
let handler: AwsLambda.APIGatewayProxy.handler =
(event, _context, cb) => {
open AwsLambda.APIGatewayProxy;
let parameter =
event
|. Event.queryStringParameters
|> Js.Option.andThen((. params) => Js.Dict.get(params, "userid"));
switch (parameter) {
| Some(userid) => Js.log2("executing lambda for", userid)
| None => Js.log("executing lambda for anonymous user")
};
let result =
switch (event |. Event.body) {
| None =>
Js.log("error: no body available in the request");
result(
~body=`Plain({|{"status": "no body available in the request"}|}),
~statusCode=400,
(),
);
| Some(body) =>
Result.make(~statusCode=200, ~body, ~isBase64Encoded=event |. Event.isBase64Encoded, ())
};
cb(Js.null, result);
Js.Promise.resolve();
};
The typescript equivalent of the type annotation is actually more verbose:
export const handle: Lambda.APIGatewayProxyHandler = async (
event: Lambda.APIGatewayEvent,
context: Lambda.Context,
cb: Lambda.APIGatewayProxyCallback) => {
}