Nightmarejs inside meteor Can't return method result

1

I am using nightmarejs in my meteor server methods to scrape a website and returns the data into the client.

But the problem is i am not able to get any data back from the server. It console.log the result in the server. It just that i can’t get it in the client side Method.call function.

1 Like
2

Ok, I think this is because of the asynchronous execution of the nightmare code in the meteor methods.
Anyway to make it synchronous, so i get the result in the client method call?

3

Sure, use e.g. the promise api that nightmarejs offers and ‘await’ its return in the method.

Am on mobile but if you post some code, I’ll help out a bit later.

4

Try the following (I haven’t tested this):

var Nightmare = require('nightmare'),
  nightmare = Nightmare({
    show: true
  });

Meteor.methods({
  'its.a.nightmare'() {
    const promise = nightmare
      //load a url
      .goto('http://yahoo.com')
      //simulate typing into an element identified by a CSS selector
      //here, Nightmare is typing into the search bar
      .type('input[title="Search"]', 'github nightmare')
      //click an element identified by a CSS selector
      //in this case, click the search button
      .click('#uh-search-button')
      //wait for an element identified by a CSS selector
      //in this case, the body of the results
      .wait('#main')
      //execute javascript on the page
      //here, the function is getting the HREF of the first search result
      .evaluate(function() {
        return document.querySelector('#main .searchCenterMiddle li a').href;
      })
      //run the queue of commands specified, followed by logging the HREF
      .then(function(result) {
        console.log(result);
      })
      //run the queue of commands specified
      //in this case, `.end()`
      .then(function() {
        console.log('done');
      })
      //catch errors if they happen
      .catch(function(error){
        console.error('an error has occurred: ' + error);
      });
    return promise.await();
  }
});
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5

Thanks.

I was missing a return keyword before the nightmare code. I thought the return inside the then function will sent the response to client. I’ll try your code. Its working now.

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6

I am just returning the nightmare like this:

return nightmare
      //load a url
      .goto('http://yahoo.com');

and its working.

Is there any difference in both? I don’t know much about promises. Even though i uses it.

7

That’s fine. Meteor automatically resolves Promises before returning from the method :slight_smile:

8

@robfallows Thanks. Then i guess what @tomsp suggested is the manual way of doing it.

9

I think it just overcomplicates things when you try to work around a problem that doesn’t exist :slight_smile:

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10

@robfallows I didn’t know it automatically resolves the promises. Do you know since when by any chance? Is it documented? Anyways, Meteor is awesome :slight_smile:

@nisthar glad you got it working. And even simpler than my suggestion. Nice!

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11

Hmm. Not sure when this was introduced, but it’s been like this for quite a while - at least a year, I think.

To add to the fun, you can also have async methods:

Meteor.methods({
  async myMethod(param) {
    const a = await someAsyncFunction(param);
    return await someOtherAsyncFunction(a);
  }
});
2 Likes
12

That does look like fun. Reminds me of the good old waterfall function from the async npm lib. In case you need to write node.js code w/o Meteors magic.

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