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.

Jeff · Accepted Answer · 2016-03-21 01:35:37Z

18

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

answered Mar 21, 2016 at 1:35

Jeff

36.7k16 gold badges117 silver badges236 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

JamesG Over a year ago

Thanks Jeff. Much Appreciated

JoeV · Accepted Answer · 2018-08-10 23:14:43Z

1

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.

answered Aug 10, 2018 at 23:14

JoeV

212 bronze badges

Comments

shashin · Accepted Answer · 2021-03-14 23:18:03Z

0

If using Java, the response can be a user defined object as below

class Handler implements RequestHandler<SQSEvent, CustomObject> {
    public CustomObject handleRequest(SQSEvent event, Context context) {
        return new CustomObject();
    }
}

Sample code can be found here.

answered Mar 14, 2021 at 23:18

shashin

711 silver badge4 bronze badges

Comments

codingforfun · Accepted Answer · 2019-07-03 21:15:10Z

-1

Do this on your result: response.json()

answered Jul 3, 2019 at 21:15

codingforfun

313 bronze badges

1 Comment

Mike Poole Over a year ago

this does not seem to answer the question. Please can you explain in more detail how this is a solution to this question.

enLighter Programmer · Accepted Answer · 2016-03-21 01:40:50Z

-2

You can use:

    res.on('end', function() {
 context.succeed(body.replace(/\\/g, '') );

To replace \ with nothing..

edited Mar 21, 2016 at 1:40

answered Mar 21, 2016 at 1:25

enLighter Programmer

4131 gold badge4 silver badges14 bronze badges

3 Comments

JamesG Over a year ago

Where do i use this?

enLighter Programmer Over a year ago

I updated the answer, if its not working try json.parse(body)

enLighter Programmer Over a year ago

@JamesG I updated the code again,, replace this code with this res.on('end', function() { context.succeed(body);

Collectives™ on Stack Overflow

JSON returning with "\" (Lambda)

5 Answers 5

1 Comment

Comments

Comments

1 Comment

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

1 Comment

Comments

Comments

1 Comment

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related