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The whole purpose of building Facebook applications is to work with the data that Facebook collects and stores about its users. Sometimes this is known as the Social Graph or the Open Graph. Facebook has a built-in language for axing that data called the Graph API. API stands for Application Programmers Interface, so let's take a look at how we can start accessing some of the basic social graph data from a user that has logged into our app. With PHP, you can make a connection to the graph API by using the API object of the Facebook class, the format for that class is right here.
So I'm going to scroll all the way down to the end and then just back up a bit to get to this section called Graph API Methods. So you can see the call requires a path then optionally a method like get post or delete, and then also optionally a list of parameters just in case you need to send information back to Facebook. Let's go back into our application, and I'll use a simple call to the graph API to get our user's information. So I'll call the Facebook object and then call the API method, then I want to pass it along a path of /me.
When you use /me as the path, you're going to get information about the user currently logged into Facebook, so let's go ahead and print out the object we get from this call. So I'm going to save this and go back to my application and refresh my screen. So you can see the data comes back as an associative array, it looks similar to a JSONobject, you can access any part of that data, so let's see if we can grab the first name and have a more personalized greeting. I am going to delete this line from right here, and I'll print out the Hello World with the user's name we get from the open graph, so I'll save this and go back into my application and refresh the browser.
So now you can see that it says Hello and then the first name of this user, instead of just Hello World. So from the array that we get back, we can see the different fields right here. The field that I used was called first name, but I could have just as easily called any of these other fields, so let's try something a little more challenging. Start output a list of the user's favorite sports, since it's part of their profile data. Not every user is going to have this as part of their profile, it depends on how much of their profile they have filled out and what privacy settings they have modified.
So first we'll check to see if sports is part of the social graph. Here I'm checking to see if the user graph has the item called sports, then I'm going to print a headline and create a list. I'm using the foreach statement to go through each of the sports listed and declare them as a key in a value and then in that loop, I go and print out every one of the name values of each sport. So let's see how that works on the browser. So I'll save this, switch back over here, let's scroll to the top, and I'll refresh my screen.
So we did everything correctly, you can see the three different items that are this user's favorite sports, you could see them right here in this array. So you can go through any of these other arrays by using the same foreach loop. If your PHP server is set to output notices, you might get a notice here, if you pick a user with no sports data. We're just experimenting with ways to access the data in this user's graph, so just look for a different field other then sports that has some data and try this technique.
We can retrieve quite a bit of information without any special permissions from the logged in user social graph. To do that we use the API method of the PHP SDK, we used just the simple path here of /me, but in reality, there's all kinds of data you can retrieve using different paths.
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