CODEWITHSUNDEEP
javascriptjquerynode.jsmongodb
Michael
Michael

Reputation: 434

Rendering mongodb database results from POST request in .ajax jquery wrapper in node js

I am creating a basic piece of functionality to allow users to send their location to a server which then queries a database and returns locations near to them. I am using the below jQuery .ajax wrapper to POST data to the server. This takes the form of a latlon point which is then used as the basis for a geosearch in MongoDB using nodejs and express on the backend. The results of the search are then intended to be returned to the client and rendered by the createMapListings function.

The /find page is initially rendered through a GET request to the database via mongodb separate from the below code. However subsequent to initial rendering, I then want to return results dependent on the location provided.

The POST method works fine and the location is posted to the server, with the search results being returned as I can print contents out through the console log.

However, I then want to render the results on the client-side. As mentioned, the results of the search render in the console, but when I attempt to pass through to the client, I can render the data itself (in the form of an array of objects) in the #output div, but the createMapListings function does not seem to catch the data.

In fact, the below function appears to be called but prints out over a thousand rows with the data that should be caught described as 'undefined'. I have tried to use res.render and res.redirect, but in the first case, the view renders in the div (which I suppose is expected) and the redirect fails.

The createMapListings function works fine when a simple GET request is made to the server, for example, for all objects in a collection, using ejs template. However, I think the issue here may be a combination of a POST request and then wanting to pass the results back to the AJAX request using the complete callback.

I apologise if the below code is somewhat obtuse. I’m definitely what you would call a beginner. I appreciate the above functionality may not possible so if there is a better way, I would of course be open to it (res.direct perhaps).

Here is the relevant client side script:

$(document).ready(function(){

$("#geolocate").click(function(){ 
navigator.geolocation.getCurrentPosition(geolocate, function(){

        });
     });
 });

function geolocate(pos){
     var latlonpt = [];
     var x = pos.coords.latitude;
     var y = pos.coords.longitude;
     latlonpt.push(x);
     latlonpt.push(y); 

    var obj = {
    userlocation: latitudelongitudept
    };

   $.ajax({
    url: "/find",
    type: "POST",
    contentType: "application/json",
    processData: false,
    data: JSON.stringify(obj),
    complete: function (data) {
        $('#output').html(data.responseText);
        $('#infooutput').children().remove();
        createMapListings(data.responseText); 
        }
     });
 };


 function createMapListings(maps) {
 for (var i = 0; i < maps.length; i++) {
 var url = maps[i]._id;
 var fullurl = "<a href='/show?id=" + url + "'>Route</a></div>";
 var title = "<div>" + maps[i].title + " - " + fullurl +"";
 $('#infooutput').append(title);

     };
  };

 </script>

Here is the relevant route used in a basic express app to handle the post request made by the above .ajax wrapper.

 exports.findbylocation = function(req, res) {
 console.log(req.body.userlocation);
 var userlocation = req.body.userlocation;
 Map.ensureIndexes;
 Map.find({loc :{ $near : userlocation }}, function(err, maps) {

 if (err) { 
          console.log(err)
          }
 else {    
       var jmaps = JSON.stringify(maps);
       console.log(jmaps);
       res.send(jmaps);
      }      
   });
};

Upvotes: 2

Views: 3230

Answers (2)

cantlin
cantlin

Reputation: 3226

By convention, the data variable name in an $.ajax callback signature refers to the parsed HTTP response body. Since your callback is on complete, we're actually passed the XMLHttpRequest used, by convention called xhr. You rightly grab the responseText property, but this needs parsing to be useful. So long as we take care over our Content-Type's and don't explicitly disable processData, jQuery will do the encoding/unencoding for us - we just deal with objects. This is a good thing, since the transport format isn't usually of any particular importance to the application logic. If we use res.json(maps) in place of res.send(jmaps), we can write our call more simply:

$.ajax({
    url:  '/find',
    type: 'POST',
    data: obj,

    success: function(data) {},
    error:   function(xhr, text, err) {}
});

Here data is a Javascript object already parsed and ready to use. We also use a default application/x-www-form-urlencoded request rather than explicitly setting a contentType. This is the same as far as express is concerned: it will just be parsed by urlencoded instead of json.

Upvotes: 4

saeed
saeed

Reputation: 3923

Assuming you solved your client-sie problem.

As you are using express there is no need for JSON.stringfy, you can use res.json(maps).

Upvotes: 0

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