Cannot get response from node.js to react.js using GET call

Question

while using an Ajax call I am trying to get data from the back-end

 componentDidMount: function () {
         $.ajax({
         url: 'http://127.0.0.1:3000/ap/test',
        dataType: 'json',
        success: function (data) {
            this.setState(data);
        }.bind(this),  error: function (xhr, status, err) {
            //   console.error(this.props.url, status, err.toString());
            console.error('failed to view user');
        }.bind(this)
    });

And here is my Get call in node.js

app.get('/test', function(req, res) {  DBs.find({},function(err,data){
if(err){ throw err;}
else {
  console.log('GET API CALLED, Data Sent!');
} sendingData = data;});   res.send(sendingData); });

1)API gets called but response isnt sent.('GET API CALLED, Data Sent!')

2)success function doesn't run in the Ajax call resulting in error: 'failed to view user'

Do you get a response from your node endpoint if you use curl? — Andy Gaskell
– Andy Gaskell, Commented Jul 29, 2017 at 21:16

Shubham Khatri · Accepted Answer · 2017-07-29 20:04:04Z

1

Your DBs.find() call will be asynchronous and hence you need to send data from the callback function of DBs.find like

app.get('/test', function(req, res) {
    DBs.find({}, function(err, data) {
        if (err) {
            throw err;
        } else {
            console.log('GET API CALLED, Data Sent!');
            res.send(data);
        }

    });
});

edited Jul 29, 2017 at 20:04

answered Jul 29, 2017 at 19:44

Shubham Khatri

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5 Comments

Yahya Ahmed Over a year ago

Still not getting the response. Used res.send(data); like you said

Shubham Khatri Over a year ago

can you console.log(data) in DB's callback, is it json

Shubham Khatri Over a year ago

One more thing can you console.log(err) in ajax success call and share me the output

Yahya Ahmed Over a year ago

It runs but it's outputting nothing

Shubham Khatri Over a year ago

Try logging xhr and see if you get something there

David Knipe · Accepted Answer · 2017-08-05 17:05:12Z

@ShubhamKhatri is right in saying that the call to res.send should be inside the callback function, so that it runs after the result of the database lookup is known.

But there's another bug: you forgot to convert the result to a JSON string before sending it. Then res.send expects a string (or maybe a buffer), so I suppose it just sends data.toString(), which would be [object Object] or something similar. Since you've used dataType: 'json', jQuery tries to read this as a JSON string. But it's not valid JSON, so the error function is called.

To fix this, just call JSON.stringify:

app.get('/test', function(req, res) {
    DBs.find({}, function(err, data) {
        if (err) {
            throw err;
            // BTW you might want less drastic error handling in this case. I'd say just send an HTTP 500 response and log something.
        } else {
            console.log('GET API CALLED, Data Sent!');
            res.send(JSON.stringify(data));
        }
    });
});

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