JBaczuk JBaczuk - 6 months ago 341
Swift Question

How to invoke an AWS Lambda function in Swift

I can't find any documentation or examples on how to invoke a Lambda function in Swift but I've tried to extrapolate from the documentation using Objective-C and I'm still getting errors:

"Error in myFunction: ValidationException: Supplied AttributeValue is empty, must contain exactly one of the supported datatypes"


It appears that I'm not passing in the parameters to the function correctly when I invoke the lambda function from swift because the script tries to write to DynamoDB but one of the parameters is empty (this lambda script works when I invoke it in javascript/node).

let lambda = AWSLambda.defaultLambda()
let request = AWSLambdaInvocationRequest()
var context = [String: String]()
let jsonString = "{\"email\":\"example@example.com\",\"name\":\"example\"}"
let jsonData = jsonString.dataUsingEncoding(NSUTF8StringEncoding)
request.clientContext = jsonData?.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.Encoding64CharacterLineLength)
request.functionName = "myFunction"
lambda.invoke(request).continueWithBlock( {
(currentTask: AWSTask!) -> AWSTask in
if (currentTask.error != nil) {
// failed to execute.
print("Error executing: ", currentTask.error)
task.setError(currentTask.error)
} else {
print("token: ", currentTask.result)
task.setResult(currentTask.result)
}
return currentTask
})

Answer

You need to set the payload parameter to a map containing the data you want to pass.

    let invocationRequest = AWSLambdaInvokerInvocationRequest()
    invocationRequest.functionName = "myFunction"
    invocationRequest.invocationType = AWSLambdaInvocationType.RequestResponse
    invocationRequest.payload = ["email" : "example@example.com", "name" : "example"]

    let lambdaInvoker = AWSLambdaInvoker.defaultLambdaInvoker()
    let task = lambdaInvoker.invoke(invocationRequest).continueWithSuccessBlock() { (task) -> AWSTask! in
        print("response: ", task.result)
    }