Passing a 'Payload' to an AWS Lambda function with the AWS PHP SDK

Question

I'm trying to use the aws php sdk to invoke a aws-lambda function and get the return value like so:

    $client = LambdaClient::factory([
        'key' => 'mykey',
        'secret' => 'mysecret',
        'region' => 'us-west-2'
    ]);

    $payload = [
        'key1' => 'value1',
        'key2' => 'value2',
        'key3' => 'value3'
    ];

    $result = $client->invoke([
        'FunctionName' => 'testFunction',
        'Payload' => json_encode($payload)
    ]);

For some reason i'm getting an ErrorException in StatusCodeVisitor.php on line 21. "Illegal string offset 'StatusCode'"

When I don't include the

'Payload' => json_encode($payload) 

Then I don't get an error, but I also don't pass any data into my lambda function which defeats the purpose.

Can anyone see anything I could be doing wrong? This seems like a trivial example.

Edit - Adding link to documentation on This function

http://docs.aws.amazon.com/aws-sdk-php/v2/api/class-Aws.Lambda.LambdaClient.html#_invoke

Answer 1

I faced the same issue and for some weird reason AWS SDK did not recognize the associate array in PHP. Maybe because at the time of JSON encoding associative array in PHP becomes object and SDK expect it as Array.

Changing $payload as follows will fix this issue.

$payload = array('test1', 'test3', 'test3');

Also remember that if you made changes in $payload you need to access them in the Lambda function as follows:

exports.handler = function(event, context) {
    console.log('value1 =', event[0]);
    console.log('value2 =', event[1]);
    console.log('value3 =', event[2]);
    context.succeed(event);  // Echo back the first key value
    // context.fail('Something went wrong');
};

Update

You can pass information like this:

$payload = array(
                "key1" => array(),
                "key2" => array()
            );