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Learn the basics of building complex, data-driven applications with the Facebook PHP SDK and MySQL. Author Ray Villalobos first introduces the fundamentals, such as checking to see if a user is logged into an application, accessing Facebook user data through the Open Graph API, and making complex API calls with the Graph API Explorer. The course then dives into building an application with API paths and Facebook Query Language (FQL) calls. Along the way, you'll discover how to post to a user's wall, upload photos, integrate with webpages, and more.
There's a small problem with our application, and it's due to the differences between working with the API through paths, or FQL. With FQL, we can easily get a list of friends who have recommended movies, but we don't have rich access to the data within the movies, like the description or the picture. With paths, we can get the rich data, but not the filtered list. The best solution is to combine both. So let's take a look. If you take a look at the application, you can see the problem. I don't always get the same amount of results when I'm on different pages. In this page I'm asking for three users, but I'm only getting two.
On the next page, I get only one user. That's because even though I'm requesting three users, only the ones that have recommended movies show up. So I can easily fix that with FQL. I can easily calculate how many friends have liked movies. So I'm going to go to this line right here, and I'll replace this user_graph query with a call to FQL. When we use an FQL query, we need to pass an array with a method of fql.query and the query that we want to process.
I already have the query that I need in the Graph API Explorer, by including this last part right here, movies does not equal blank, this will return only the friends that have liked movies. So I'm going to copy this and come back here and paste that into our query. To calculate how many friends we have, we need to modify how we count the results. If you remember from the previous movie, the array we get in return doesn't have the data object, so we can take that out. There's a couple of lines I calculate our movies path right now, and we're going to create a new version so we'll delete these. So I'll set up another FQL call right here.
I also have this version in another call to the API Graph Explorer. Now, using an OFFSET in this query is going to cause a problem if we leave the code like it is because when the application first runs, OFFSET would not have a value. So if we take this out, and we try to run this query, we'll get an error. The keyword OFFSET always has to have a number next to it. So if we copy and switch back to our application, we'll paste it right here, and we'll pass it along the quantity variable and normally I would pass it along the currentoffset here.
But I can't do that because the first time this runs, currentoffset will not have a value, and this would result in a bad query. So I need to take this out of here and add another variable here called offsettext, and if the variable called currentoffset exists, then it's going to set the offsettext variable to OFFSET plus the currentoffset. If it doesn't exist, then it will just make it blank.
So now we can pass this offsettext variable right here. This question mark is known as a ternary operator, and it's sort of a shorthand if statement. It will make an assignment to offsettext, depending on whether or not the statement is true or false. Now we need to adjust our foreach statement. We'll use the moviefriends_graph variable, and we don't need to use this data field because the FQL queries are not going to return the data object.
I don't need this if statement right here, because that's used to check if the user had at least one recommendation, and we're only getting movies that already have recommendations. So I can delete this right here and make sure that I delete the second part of it, which is down here. Now, weirdly enough, when you query the API with paths, it returns the user ID as a field called id. When you do an FQL query, it returns it as something called uid. So we need to change the ID right here to uid, and this one as well.
Now we're ready to pull the graph for the info about each user's movie graph. We'll do that with the regular call to the API with the path. And our foreach statement is going to use this new movies_graph variable. I will need to leave the data object because this is a path API call. So let's go back into our application and hit the Refresh button. And if everything is working correctly, this page should have three users, and it does.
And I should only have two pages, because I only have four friends that have recommended movies. So by combining our two query types, we were able to get the best of both worlds, a list of only friends who like movies, as well as detailed information about the movies using an Open Graph path. It's definitely always better to have many tools in your Web Development Toolbox.
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