JSON returning with "\" (Lambda)

Question

I am using AWS Lambda to get JSON from the open weather api and return it.

Here is my code:

var http = require('http');

exports.handler = function(event, context) {
    var url = "http://api.openweathermap.org/data/2.5/weather?id=2172797&appid=b1b15e88fa797225412429c1c50c122a";
    http.get(url, function(res) {
        // Continuously update stream with data
        var body = '';
        res.on('data', function(d) {
            body += d;
        });
        res.on('end', function() {
            context.succeed(body);
        });
        res.on('error', function(e) {
            context.fail("Got error: " + e.message);
        });
    });
}

It works and returns the JSON, but it is adding backslashes before every " like so:

"{\"coord\":{\"lon\":145.77,\"lat\":-16.92},\"weather\":[{\"id\":803,\"main\":\"Clouds\",\"description\":\"broken clouds\",\"icon\":\"04d\"}],\"base\":\"cmc stations\",\"main\":{\"temp\":303.15,\"pressure\":1008,\"humidity\":74,\"temp_min\":303.15,\"temp_max\":303.15},\"wind\":{\"speed\":3.1,\"deg\":320},\"clouds\":{\"all\":75},\"dt\":1458518400,\"sys\":{\"type\":1,\"id\":8166,\"message\":0.0025,\"country\":\"AU\",\"sunrise\":1458505258,\"sunset\":1458548812},\"id\":2172797,\"name\":\"Cairns\",\"cod\":200}"

This is stopping my over service using (SwiftJSON) detecting this as valid JSON.

Can anyone tell me how to make the API information come out as correctly formatted JSON?

I tried .replace like so:

 res.on('end', function() {

        result = body.replace('\\', '');
        context.succeed(result);
    });

It did not change anything. Still had the same output.

Answer 1

You're posting it as a string.

Try context.succeed(JSON.parse(result))

From the docs

The result provided must be JSON.stringify compatible. If AWS Lambda fails to stringify or encounters another error, an unhandled exception is thrown, with the X-Amz-Function-Error response header set to Unhandled.

http://docs.aws.amazon.com/lambda/latest/dg/nodejs-prog-model-context.html

So essentially it's taking your json string as a string and calling JSON.stringify on it...thus escaping all the quotes as you're seeing. Pass the parsed JSON object to succeed and it should not have this issue

Answer 2

In case of Java, just return a JSONObject. Looks like when returning string it is trying to do some transformation and ends up escaping all the quotes.