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how to create a public photo uploader using flickr ?

There are many instances where you will need to create a photo uploader on your website so that anyone or a selective audience can upload their photos to a common pool. In this post, I will explain to you how we can create such a photo uploader using Flickr.

Finished product

At the end of this post, you would have learnt to build a Public Photo Uploader using Flickr. Photos uploaded in the previous link are visible at rkj_flickr stream.

Create a Flickr account

You can login to Flickr via Yahoo! or Google or Facebook ID. You can signup with flickr @ Create Flickr Account. I would recommend you to create a Yahoo! user account as Flickr is owned by Yahoo!.

I created a Yahoo! account named rkj_photo_uploader@yahoo.com. Now, let us sign into flickr @ Flickr Sign In. Now flickr will ask you to create a Flickr username to associate with your account. This is different than your Yahoo! account. Let us choose rkj_flickr as the flickr username. If everything succeeds, congratulations!!! you created a new Flickr account.

Create a Flickr application

You can browse your flickr apps @ Flickr Apps. Follow the below steps to create a new flickr app:-

  • Create a new non-commercial app @ http://www.flickr.com/services/apps/create/noncommercial/.
  • Fill in the name of your app and description and create the app.
  • Once you do this, you will get a screen like below which specifies the "API Key" and "Secret" for your application. Please note both of them in a text file which will be later used in our photo uploader.
flickr API key and secret

Flickr API

You can browse the Flickr API documentation @ http://www.flickr.com/services/api/. Either, you can use the Flickr API directly to build the Photo Uploader or we can use phpFlickr which is basically a php wrapper on top of Flickr API which does all the stuff like making curl call, passing required params, error handling etc. Due to these advantages, we will use phpFlickr library to access Flickr API.

You can download phpFlickr library at phpFlickr - github. In order to run phpFlickr, you will need to install php and curl libraries. If you don't have them, refer to Setup PHP cURL on Ubuntu to setup php and curl on your webserver.

Clone or extract the compressed file of phpFlickr library on your webserver. The next step is the most critical part of getting your photo uploader working.

Generate API token

Basically, when someone uploads a photo using your photo uploader, we somehow need to figure out a way to send this photo to flickr, but this process needs authentication. So, in order to let anyone upload photo to your flickr stream, we will need to generate a API token and hard-code it our code so that we will authenticate on the uploader's behalf.

In the phpFlickr library, you will find "getToken.php" whose content are as below.

<?php
     /* Last updated with phpFlickr 1.4
      *
      * If you need your app to always login with the same user (to see your private
      * photos or photosets, for example), you can use this file to login and get a
      * token assigned so that you can hard code the token to be used.  To use this
      * use the phpFlickr::setToken() function whenever you create an instance of
      * the class.
      */

     require_once("phpFlickr.php");
     $f = new phpFlickr("<api key>", "<secret>");

     //change this to the permissions you will need
     $f->auth("read");

     echo "Copy this token into your code: " . $_SESSION['phpFlickr_auth_token'];
 ?>

We will slightly modify the above code to suit our needs. In the modified getToken.php below, make the following changes to customize it to your app :-

  • Replace the "__your__app__apikey__" and "__your__app__secret__" with those which you noted down after you created the flickr app.
  • Since you want to upload photos to your flickr photo stream, you will need "write" permission.
  • Also, if the user has not yet authenticated, $_GET["frob"] will be empty. Before a user can use the app, he/she needs to request a "frob" and generate a token from the frob.
  • Once you have the frob, use "$f->auth_getToken($_GET['frob'])" to generate the token.
  • var_dump just prints out the $tokenArgs variable.

I know this part can be a little confusing, just think of this process as getting a precious "token" which will magically enable anyone to upload photos to your flickr photo stream.

<?php
     /* Last updated with phpFlickr 1.4
      *
      * If you need your app to always login with the same user (to see your private
      * photos or photosets, for example), you can use this file to login and get a
      * token assigned so that you can hard code the token to be used.  To use this
      * use the phpFlickr::setToken() function whenever you create an instance of
      * the class.
      */

     require_once("phpFlickr.php");

     $apiKey = "__your__app__apikey__";
     $secret = "__your__app__secret__";
     $perms = "write";

     $f = new phpFlickr($apiKey, $secret);

     //Redirect to flickr for authorization
     if(!$_GET['frob']){
         $f->auth($perms);
     }else {
         //If authorized, print the token
         $tokenArgs = $f->auth_getToken($_GET['frob']);
         echo "<pre>"; var_dump($tokenArgs); echo "</pre>";
     }
?>

Edit Authentication flow

Before you can execute the above modified getToken.php file, you will need to make some changes to your flickr app. Go to your app in flickr and click on "Edit the authentication flow".

edit authentication flow

Choose Web Application as App Type and enter the callback url as the path to "getToken.php" on your webserver. This is the webpage url where flickr will redirect you after authentication is done.

flickr callback URL

Authorize the app

Now, in the browser, hit getToken.php i.e, http://__yourwebserver__/__path_to_phpFlickr__/getToken.php. If you have not logged in with the account to which photos need to be uploaded, do that. After logging in, an authorization screen is shown, click "Ok, I'll authorize it".

flickr authorize app

Finally, generate the token and store it

After, the above is done, you will see an output of tokenArgs as below. The most important part is the "token", which you will need to copy and store it safely in a text file, which will be used later.

flickr api token arguments

PHP Logic to upload a file to webserver and then to flickr

Now that you have the API Key, Secret and Token, it's just a matter of building a basic file uploader on your website. Whenever a user uploads a file, we will upload it to a temp directory on your webserver and then post it to flickr with above credentials.

If you want to learn basics of file uploading via PHP, please refer to http://php.net/manual/en/reserved.variables.files.php and http://www.php.net/manual/en/features.file-upload.post-method.php for more details. I will assume that you know how to deal with file uploading in PHP and go ahead with the flow.

Some more minor details to cover while implementing a photo uploader are listed below.

  • Restrict file-type to "jpeg", "jpg", "gif", "png".
  • Restrict file-size so that people don't upload big files of 2-3MB. In my case, I will restrict it to "512KB".

In the below code, once file uploading is done, we call the function "uploadPhoto". Here, we basically instantiate a phpFlickr object through our apiKey and secret.

The next step is critical, we need to assign the token generated previously to this object using $f->setToken($token). You can upload the file now by calling, $f->async_upload($path, $title), which returns a ticket_id through which you can track your upload.

There is one more method that you can use to upload a photo to flickr via phpFlickr, namely, $f->sync_upload() which basically waits until Flickr processes the photo and returns the photo ID. You can find more details about these two methods of uploading at https://github.com/dan-coulter/phpflickr/blob/master/README.md.

 <?php
     //Include phpFlickr
     require_once("phpFlickr/phpFlickr.php");

     $error=0;
     $f = null;
     if($_POST){
         if(!$_POST['name'] || !$_FILES["file"]["name"]){
             $error=1;
         }else{
             if ($_FILES["file"]["error"] > 0){
                 echo "Error: " . $_FILES["file"]["error"] . "<br />";
             }else if($_FILES["file"]["type"] != "image/jpg" && $_FILES["file"]["type"] != "image/jpeg" && $_FILES["file"]["type"] != "image/png" && $_FILES["file"]["type"] != "image/gif"){
                 $error = 3;
             }else if(intval($_FILES["file"]["size"]) > 525000){
                 $error = 4;
             }else{
                 $dir= dirname($_FILES["file"]["tmp_name"]);
                 $newpath=$dir."/".$_FILES["file"]["name"];
                 rename($_FILES["file"]["tmp_name"],$newpath);
                 //Instantiate phpFlickr
                 $status = uploadPhoto($newpath, $_POST["name"]);
                 if(!$status) {
                     $error = 2;
                 }
              }
          }
     }

     function uploadPhoto($path, $title) {
         $apiKey = "__your__app__apikey__";
         $apiSecret = "__your__app__secret__";
         $permissions  = "write";
         $token        = "__your__generated__token__";

         $f = new phpFlickr($apiKey, $apiSecret, true);
         $f->setToken($token);
         return $f->async_upload($path, $title);
     }
 ?>

Now that we have the php part of the code working, let's weave HTML around it so that user can upload his photo and get confirmation. We will also do some basic error handling by embedding some PHP code.

 <body>
     <div id="doc" class="yui-t7">
        <div id="hd" role="banner"><h1>Photo Uploader Using Flickr</h1></div>
        <div id="bd" role="main">
        <div id="mainbar" class="yui-b">
     <?php

     if (isset($_POST['name']) && $error==0) {
         echo "  <h2>Your file has been uploaded to <a href='http://www.flickr.com/photos/61074807@N08/' target='_blank'>rkj_flickr's photo stream</a></h2>";
     }else {
         if($error == 1){
             echo "  <font color='red'>Please provide both name and a file</font>";
         }else if($error == 2) {
             echo "  <font color='red'>Unable to upload your photo, please try again</font>";
         }else if($error == 3){
             echo "  <font color='red'>Please upload JPG, JPEG, PNG or GIF image ONLY</font>";
         }else if($error == 4){
             echo "  <font color='red'>Image size greater than 512KB, Please upload an image under 512KB</font>";
         }
     ?>
       <h2>Upload your Pic!</h2>
       <form  method="post" accept-charset="utf-8" enctype='multipart/form-data'>
         <p>Name: &nbsp; <input type="text" name="name" value="" ></p>
         <p>Picture: <input type="file" name="file"/></p>
        <p><input type="submit" value="Submit"></p>
       </form>
       <?php
     }
     ?>
           </div>
        </div>
        <div id="ft"></div>
     </div>
 </body>

If you append both the logic given above, you have a public photo uploader ready. Whenever, anyone uploads the photo, it directly goes to your flickr stream. In my case, it goes to rkj_flickr stream.

You can try out the public photo uploader at Flickr Photo Uploader. Upload your photo and check if it appears in rkj_flickr stream. Good luck !

Complete Source Code : https://github.com/ravikiranj/flickr-photo-uploader

Notes

  • If you get a open_basedir restriction error or unable to include file error in php, please refer to set_include_path and php.ini help to resolve this issue.

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