aws lambda call not populating body on POST

Question

Thanks to help from EVK on my previous Q (can use API GET but not API POST) I was able to resolve the problem of not being able to make an API POST request from an aws lambda in node, when I could hit the GET. The problem was not populating post_options.

Anyway, now I am able to successfully call the post but I cant get the body populated.

related documentation https://nodejs.org/api/http.html#http_http_request_options_callback

If you see my API POST call below.

 //// POST api/<controller>
      public string SapEaiCall([FromBody]string xmlFile)
        {
            string responseMsg = "Failed Import Active Directory User";

            if (string.IsNullOrEmpty(xmlFile))
            {
                responseMsg = "XML file is NULL";
            }

            if (responseMsg != "XML file is NULL")
            {
                xmlFile = RemoveFirstAndLastQuotes(xmlFile);

                if (!IsNewestVersionOfXMLFile(xmlFile))
                {
                    responseMsg = "Not latest version of file, update not performed";
                }
                else
                {
                    Business.PersonnelReplicate personnelReplicate = BusinessLogic.SynchronisePersonnel.BuildFromDataContractXml<Business.PersonnelReplicate>(xmlFile);
                    bool result = Service.Personnel.SynchroniseCache(personnelReplicate);

                    if (result)
                    {
                        responseMsg = "Success Import Sap Cache User";
                    }
                }
            }

            return "{\"response\" : \" " + responseMsg + " \" , \"isNewActiveDirectoryUser\" : \" false \"}";

        }

Every time I call it from the aws lambda, it returns responseMsg = "XML file is NULL";

Please see my example below:

    var querystring = require('querystring');
var https = require('https');
var fs = require('fs');

exports.handler = function(event, context) {

   const post_data = querystring.stringify({'msg': 'Hello World!'});

    // An object of options to indicate where to post to
    var post_options = {
        host: 'URL',
        protocol: 'https:',
        port: '443',
        path: '/api/SyncPersonnelViaAwsApi/SapEaiCall',
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
            'Content-Length': post_data.length
        }
    };

    //ignores SSL
   process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";
    var post_request = https.request(post_options, function(res) {
        var body = "";

        res.on('data', function(chunk)  {
            body += chunk;
        });

        res.on('end', function() {
            context.done(body);
        });

        res.on('error', function(e) {
            context.fail('error:' + e.message);
        });
    });

    // post the data
    post_request.write(post_data);
    post_request.end();
 console.log("posted data " +post_data); //returns posted data msg=Hello%20World!
};

So I have populated post data, and also tried populating the body. Still returns XML file is NULL

Does anyone please have any idea why?

Thanks

From the code you provided, it looks like your post method not able to get the xmlFile which should be part of your post_options which you are not passing. show us how you are calling this post endpoint with all the params from postman. — kgangadhar
yes for the purpose of testing I removed the actual xml file and populated the post_data with Hello World!...are you saying this should be added to the post_options?, and if so as what param please? — John
Ya, i think if you want to test with hello world data then you need to include json:post_data inside your post_options . — kgangadhar
although that does make sense I could find that option available in the docs nodejs.org/api/http.html#http_http_request_options_callback I did try what you suggested tho but unfortunately if didnt work — John

Evk Evk · Accepted Answer · 2018-04-12T07:45:23

You are sending the following text in body:

msg=Hello%20World!

And you state that request content type is:

'Content-Type': 'application/json'

Does your body represents valid json? It doesn't. So that's first problem - content type stated in your request and actual data your send do not match each other.

Then let's look at:

public string SapEaiCall([FromBody]string xmlFile)

It basically says: look at the body of request and use binder appropriate for request content type to bind value of xmlFile parameter. Since request content type is "application/json" - binder expects body to contain one single json string, that is, body in such case should be (including quotes):

"Hello World!"

So if you pass that (for example via const post_data = JSON.stringify('Hello World!'); - it should work.

But then what if you want to pass more parameters in your body, not just xmlFile? Then you need to define a model, and I'd say even if you have just one parameter - it's better to do that. For example:

public class SapEaiCallParameters {
    public string XmlFile { get; set; }
}

// FromBody can be omitted in this case
public IHttpActionResult Post(SapEaiCallParameters parameters) {

}

And then you call it as you would expect, passing json:

const model = {xmlFile: 'Hello World!'};
const post_data = JSON.stringify(model);

Side note: don't do this:

return "{\"response\" : \" " + responseMsg + " \" , \"isNewActiveDirectoryUser\" : \" false \"}";

Instead, create another model, like this:

public class SapEaiCallResponse {
    public string Response { get; set; }
    public bool IsNewActiveDirectoryUser { get; set; }
}

And return it:

    public IHttpActionResult Post(SapEaiCallParameters parameters) {
        ...
        return Json(new SapEaiCallResponse {
            Response = responseMsg,
            IsNewActiveDirectoryUser = false,
        });
    }

aws lambda call not populating body on POST

1 Answers