使用Json将标记添加到Google Maps | API

Question

I'm trying to plot markers on a google map using data from a Json Response. I have searched Stack Overflow for an answer all day but havn't managed to find a solution that has worked for me.

I'm guessing it has something to do with the way I am extracting the Lat & Lng but just can't put my finger on it. Below are my code and the Json, the Json is from an API.

Where is the error in my code?

Script

<script>   
  function initialize() {
              var myOptions = {
                  zoom: 4,
                  center: new google.maps.LatLng(34.397, 150.644),
                  mapTypeId: google.maps.MapTypeId.ROADMAP
              };

              map = new google.maps.Map(document.getElementById("map"), myOptions);
              };

  function getLocations() {

      $.getJSON("URL", function (json) {

          $.each(json["resultsPage"]["results"]["event"], function(i, entry){
              addMarker(entry.location.lat,entry.location.lng);
          });
      });
  }

  function addMarker(lat,lng) {
          marker = new google.maps.Marker({
          position: new google.maps.LatLng(lat,lng),
          map: map,
          });
          markersArray.push(marker);
  }
  </script>

Json Response

Told to request Json data by using the following code. If I leave the question mark at the end I get an invalid message when I run it through http://jsonlint.com as there is a question mark at the beginning of the Json. Taking that out appears to solve the problem but I'm not 100% sure that that is ok?

    $.getJSON("http://api.songkick.com/api/3.0/events.json?location=clientip&apikey={your_api_key}&jsoncallback=?",
    function(data){
    // data is JSON response object
    });

If I leave the question mark at the end I get an invalid message when I run it through http://jsonlint.com as there is a question mark at the beginning of the Json. Taking that out appears to solve the problem but I'm not 100% sure that that is ok?

When I view the code in debugger I get " SyntaxError: Unexpected token ':' ", but this response is coming from an API so I am unsure what I can do about it?

    {
    "resultsPage": {
    "status": "ok",
    "results": {
        "event": [
            {
                "type": "Concert",
                "status": "ok",
                "performance": [
                    {
                        "artist": {
                            "displayName": "Arcade Fire",
                            "uri": "http://www.songkick.com/artists/66758-arcade-fire?utm_source=16289&utm_medium=partner",
                            "identifier": [
                                {
                                    "mbid": "52074ba6-e495-4ef3-9bb4-0703888a9f68",
                                    "href": "http://api.songkick.com/api/3.0/artists/mbid:52074ba6-e495-4ef3-9bb4-0703888a9f68.json"
                                }
                            ],
                            "id": 66758
                        },
                        "billingIndex": 1,
                        "billing": "headline",
                        "displayName": "Arcade Fire",
                        "id": 29913729
                    },
                    {
                        "artist": {
                            "displayName": "Doody and Kami",
                            "uri": "http://www.songkick.com/artists/6334389-doody-and-kami?utm_source=16289&utm_medium=partner",
                            "identifier": [],
                            "id": 6334389
                        },
                        "billingIndex": 2,
                        "billing": "support",
                        "displayName": "Doody and Kami",
                        "id": 29913734
                    },
                    {
                        "artist": {
                            "displayName": "Leah Gordon",
                            "uri": "http://www.songkick.com/artists/6334394-leah-gordon?utm_source=16289&utm_medium=partner",
                            "identifier": [],
                            "id": 6334394
                        },
                        "billingIndex": 3,
                        "billing": "support",
                        "displayName": "Leah Gordon",
                        "id": 29913739
                    }
                ],
                "venue": {
                    "metroArea": {
                        "country": {
                            "displayName": "Canada"
                        },
                        "state": {
                            "displayName": "QC"
                        },
                        "displayName": "Montreal",
                        "uri": "http://www.songkick.com/metro_areas/27377-canada-montreal?utm_source=16289&utm_medium=partner",
                        "id": 27377
                    },
                    "lat": 45.5014288,
                    "displayName": "Phi Center",
                    "lng": -73.5564459,
                    "uri": "http://www.songkick.com/venues/1973969-phi-center?utm_source=16289&utm_medium=partner",
                    "id": 1973969
                },
                "popularity": 0,
                "location": {
                    "lat": 45.5014288,
                    "lng": -73.5564459,
                    "city": "Montreal, QC, Canada"
                },
                "start": {
                    "time": null,
                    "date": "2013-02-23",
                    "datetime": null
                },
                "displayName": "Arcade Fire with Doody and Kami and Leah Gordon at Phi Center (February 23, 2013)",
                "uri": "http://www.songkick.com/concerts/15215934-arcade-fire-at-phi-center?utm_source=16289&utm_medium=partner",
                "id": 15215934
            }
        ]
    },
    "perPage": 50,
    "page": 1,
    "totalEntries": 1
    }
    }  

Any help would be greatly appreciated. Thanks

Updated

Answer 1

Was able to reproduce you error.

The API which you are consuming doesn't support callback. you need to create a proxy and have to hit proxy from you code and your proxy will in turn call the api.

here is the code

index.html

        function getLocations() {
            $.ajax({
                type: "GET",
                url: "http://172.20.6.114/ontrack/data.php?callback=?",
                dataType: "jsonp",
                success: function(json){
                    $.each(json["resultsPage"]["results"]["event"], function(i, entry){
                        PlotMarker(entry.location.lat, entry.location.lng);
                    });
                },
                error: function(err){
                    console.log(err);
                }
            });
        }

        function PlotMarker(lat, lon){
            var marker = new google.maps.Marker({
                position: new google.maps.LatLng(lat, lon),
                map: gmap,
                draggable: false,
                animation: google.maps.Animation.DROP
            });
            markerLocations.push(marker);
        }

Code for data.php

<?
$ch = curl_init();

curl_setopt($ch, CURLOPT_URL,"http://api.songkick.com/api/3.0/events.json?location=clientip&apikey={your_api_key}");

// receive server response ...
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$server_output = curl_exec($ch);

curl_close($ch);

echo $_GET['callback'] . '(' . $server_output . ');';
?>

Then it will show up.

Answer 2

Your json is invalid, "resultsPage:" { should be "resultsPage" : { , the colon is inside the double quotes, you can validate your json using jsonlint.com . Here is an example using valid (edited) json which is printing lat, lng in the console.

Invalid json error from jsonlint.com

Update: You can also try this (for checking)

function myCallBack(data){
    console.log(data);
}
<script type="text/javascript" src="http://api.songkick.com/api/3.0/events.json?location=clientip&apikey={your_api_key}&jsoncallback=myCallBack"></script>

Answer 3

The &jsoncallback=? can be deleted safely

Here's my view on that:

If you use the following code:

$.getJSON("http://api.songkick.com/api/3.0/events.json?location=clientip&apikey={your_api_key}&jsoncallback=?",
    function(data){
    // data is JSON response object
    });

Then, you don't need (probably) a json callback, since you are already using one after the comma (2nd parameter to getJSON function).

So you can simply delete the &jsoncallback=? from your URL and make it to http://api.songkick.com/api/3.0/events.json?location=clientip&apikey={your_api_key}

Here's what is going on -

-- To facilitate JSONP (and Cross Domain AJAX request) you are sending a callback function to the URL

-- The Server then reads the jsoncallback=XYZ and then returns you the data wrapped in XYZ function call

-- So that you can define XYZ function in your JavaScript somewhere like the following:

function XYZ(jsonDATA) {
    // ... And do things Here. JSONP is cool !    
}

-- But Since you already have a functioning callback to the getJSON function, you don't need the &jsoncallback=something and can therefore delete it

PS : as a proof to above, try hitting the URL http://api.songkick.com/api/3.0/events.json?location=clientip&apikey={your_api_key}&jsoncallback=MyFunction in your browser and you will get the following response in one line:

MyFunction({
    "resultsPage": {
        "status": "error",
        "error": {
            "message": "Invalid or missing apikey"
        }
    }
})

UPDATE:
To address your JavaScript error in comment --
Even though the response is a valid JSON , you are using the response as a JavaScript code, which is invalid

It would be a valid JavaScript code if you make it like this:

var myData = {
    "resultsPage": {
        "status": "error",
        "error": {
            "message": "Invalid or missing apikey"
        }
    }
}

But my point is, why are you checking the console error with this JSON data? Console is for JavaScript