Filter nested JSON based on specific value

Question

I know there have been a lot of questions about how to handle JSON and I have tried quite a few, but am really stuck.

What I am trying to achieve is the following:
I load a JSON and in that JSON, there is information about photos. Each photos has several attributes, one of them being the latitude and longitude.These have not been specified for all the photo's. I want to have a JSON object in the end which contains only the photo's with a lat/long value.

The JSON looks like this:

{
    "current_page": 1,
    "total_pages": 2,
    "total_items": 27,
    "photos": [{
                "id": 63151715,
                "user_id": 430997,
                "name": "Footsteps",
                "description": "Traces in the dunes",
                "camera": "Canon EOS 5D Mark II",
                "lens": null,
                "focal_length": "23",
                "iso": "50",
                "shutter_speed": "30",
                "aperture": "9",
                "times_viewed": 500,
                "rating": 44.2,
                "status": 1,
                "created_at": "2014-03-08T06:02:13-05:00",
                "category": 8,
                "location": null,
                "latitude": 52.399774296136734,
                "longitude": 4.558639526367187

And them some more attributes and photos. I have validated it and that seems ok.

var json = $.getJSON("https://api.500px.com/v1/photos?feature=user&username=bzwemmer&consumer_key=XXX",
    function (json) {
        console.log(json);
    });

var jobj = $.parseJSON(json);

for (var i = 0; i < jobj.length; i++) {
    var type = "point";
    // Path from json from Firebug = json.responseJSON.photos[0].latitude 
    var lat = json.responseJSON.photos[0].latitude;
    console.log(lat);
    if (lat !== null || lat !== "") {
        geoobj.photos.push({
            lat: photos.lat,
            lon: photos.lon,
            name: photos.name,
            image_url: photos.image_url
        });
    }
}

I want to select a couple of attributes and put them in another JSON for furter processing. However, with everything I try, I get the message in Firebug that lat = undefined.

I hope someone knows where I am going wrong, because I don't see it anymore.

You're not filtering JSON, you're filtering information in a JavaScript object. JSON exited the picture after the var jobj = $.parseJSON(json); line. — T.J. Crowder
– T.J. Crowder, Commented Jun 28, 2014 at 15:05
Thanks TJ, I realize my "programming vocabulary" is not what it should be — bzwemmer
– bzwemmer, Commented Jun 30, 2014 at 10:29

bzwemmer · Accepted Answer · 2014-07-02 11:47:11Z

3

You are trying to access result outside of callback function. it will not work. always process result inside callback function. try following code.

<script type='text/javascript'>

    $.getJSON("https://api.500px.com/v1/photos?feature=user&username=bzwemmer&consumer_key=XXX", function(json) {

        var jobj = $.parseJSON(json);

        $(jobj.photos).each(function(ind, val){
            if(val.latitude != "" && val.longitude != "") {
                geoobj.photos.push({
                lat: val.latitude,
                lon: val.longitude,
                name: val.name,
                image_url: val.image_url});  
            }
        });
    });

</script>

edited Jul 2, 2014 at 11:47

bzwemmer

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answered Jun 28, 2014 at 15:06

Rashmin Javiya

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6 Comments

T.J. Crowder Over a year ago

And use jobj rather than json.responseJSON

jcaron Over a year ago

also I don't believe the test against "" is the right one. typeof val.latitude !== 'undefined' is probably more appropriate

Rashmin Javiya Over a year ago

Oh sorry i forget to remove OP's forloop

ajh158 Over a year ago

If you look at the response to OPs request, latitude and longitude can be null. Seems like it would be better to just do if(val.latitude && val.longitude)?

ajh158 Over a year ago

Also, I don't think you need to do $.parseJSON(json) - the response is already valid JSON, so you can just use it directly instead of jobj.

|

Danyu · Accepted Answer · 2014-06-28 15:10:10Z

0

If you json is valid, it should work, check this jsfiddle sample,

Following is simplified version

var jsonObj={
         "current_page":1,
          "total_pages":2,
          "total_items":27,
          "photos":
               [{"latitude":52.399774296136734,
                 "longitude":4.558639526367187}]
         };

alert(jsonObj.photos[0].latitude);

answered Jun 28, 2014 at 15:10

Danyu

5073 silver badges7 bronze badges

Comments

Community · Accepted Answer · 2017-05-23 11:58:05Z

0

You should accept Rashmin Javiya's answer. I started to answer the same way, but she beat me to it!

Here is a fixed version of your code that handles the pagination and writes some debug output.

var geoobj = {photos:[]};
var missingLLcounter = 0;
(function getPhotos(page) {
    var request = "https://api.500px.com/v1/photos?feature=user&username=bzwemmer&consumer_key=ByGjMRRao3aAozGsq6HuxZmJfA6ufWzNL32VPplp&page="+page;

    console.log('getting page '+page+': '+request);

    $.getJSON(request, function (json) {
        $(json.photos).each(function(ind, val) {
            if(val.latitude && val.longitude) {
                geoobj.photos.push({
                    lat: val.latitude,
                    lon: val.longitude,
                    name: val.name,
                    image_url: val.image_url
                });
            } else {
                missingLLcounter++;
            }
        });

        console.log('done with page '+page+', '+(json.total_pages-page)+' pages to go.');

        if(json.total_pages>page) {
            getPhotos(++page);
        } else {
            console.log('done! retrieved '+page+' page'+(page>1?'s':'')+' with '+(geoobj.photos.length+missingLLcounter)+' total records ('+missingLLcounter+' were missing lat/lngs).');
        }
    });
})(1);

edited May 23, 2017 at 11:58

CommunityBot

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answered Jun 28, 2014 at 15:11

ajh158

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1 Comment

bzwemmer Over a year ago

Thanks, I accepted it. I'm just not every day in front of a PC for this stuff.

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