Facebook offers a flexible and easy to use API called Graph, graph is simply a URL that once you open in a browser or within your code it return a JSON (JavaScript Object Notation ) string, in this tutorial you will learn how to use php and facebook graph API to access public posts and parse JSON results with php, We will build together a php  search engine to parse JSON returned by Facebook Graph and display results to visitors

view this in action Demo

If you don’t know what is Json, a Json string looks like this

{
"name": "John Smith",
"Age": "30",
"username": "Jsith",
"location": "Chicago"
}

Our search engine will be 2 pages

index.html
search.php

index.html content

<form action="search.php" method="post">
<input type="text" name="keyword">
<input type="submit" value="search">
</form>

in the above step we build a basic html page with a form that contains text field and submit button to submit the form to our search.php, then once a user type a keyword and hit submit we want to take that keyword and search facebook public posts suing their graph API.

Now in search.php We need to catch the submitted keyword from index.html

$keyword = $_POST['keyword'];

The graph url which will return a JSON string is https://graph.facebook.com/search
the url accepts many parameters but we will use the basic ones such as type and q (query)
you can see what the JSON results would look like before we parse them with PHP here:
https://graph.facebook.com/search?q=hello&type=post
Now lets set the graph url we will be opening with php

// set graph url
$graph_url = "https://graph.facebook.com/search?";
// add parameters to graph url
$graph_url .= "&type=posts";
$graph_url .= "&q=$keyword";

in the above step we have a prepared graph url with type parameter and q parameter, the q parameter is the keyword we want to search for and type is the kind of contents we need, we are going to search for posts, aren’t we?
Now that facebook graph url is ready with the keyword we want to search for, lets have php open it so it returns the JSON results

$results = file_get_contents( $graph_url );

$result will be the variable holding the JSON data returned by Facebook Graph, We now need to parse JSON and display it as readable text or HTML content, We will parse it using php function – json_decode() -

$json = json_decode($results);

the json_decode() function in the way used above converts the JSON string into accessible objects, We will need to do a foreach loop to access those objects and print them, lets do that now

foreach( $json->data as $show ) {
echo $show->from->name . "\n";
echo $show->message . "\n";
echo $show->created_time . "\n"
echo "<hr>";
}

Now you might be wondering why used $json->data and not $json alone, the answer is because all the returned results in JSON are inside an array called “data” and also you may have noticed to show the name of poster I’m doing $json->from->name is because “from” is an array and name is an object inside that array you can see how it looks like here https://graph.facebook.com/?q=hello&type=post, In this tutorial I’m only showing name of person who made the post, message which is post content, created time is the timestamp of the post date you can access many more such as Facebook user ID , description, comments count etc. By simple doing $show->xx where xx is the object name! I hope this helps you in your next Facebook app project! you can what we have created in action here

search.php all together will look like this

$keyword = $_POST['keyword'];
$graph_url = "https://graph.facebook.com/search?";
$graph_url .= "&type=posts";
$graph_url .= "&q=$keyword";
$results = file_get_contents( $graph_url );
$json = json_decode($results);
foreach( $json->data as $show ) {
echo $show->from->name . "\n";
echo $show->message . "\n";
echo $show->created_time . "\n"
echo "<hr>";
}