A presentation at Chicago PHP User Group in in Chicago, IL, USA by Carly Ho
f C F API P f
Carly Ho Sr. Engineer, Clique Studios (here!) @carlymho
W ’ API ﹡ Application Programming Interface ﹡ A way to programmatically retrieve data for display, transformation, etc. ﹡ Usually accessed via an endpoint URL ﹡ Usually returns data in JSON format
H API ? ﹡ In PHP, we have file_get_contents and the native cURL (“client URL”) implementation ﹡ We can also use Javascript in any page to perform API calls on particular browser events
⚠AW fW ⚠ ﹡ There is danger inherent to getting data from a third party ﹡ External servers might be compromised unexpectedly ﹡ Sanitize data like you would your form inputs!
U E API
G API D ﹡ The easiest way is to use file_get_contents(‘https://your-url.com /’), which, when returned to a variable, will fetch the contents ﹡ However, it’ll be a string, rather than an object we can use
JSON H P I ﹡ JSON (JavaScript Object Notation) is the format for most API data ﹡ When we use JavaScript to fetch API data, it can usually use it right away, but in PHP, whether we use file_get_contents or cURL we need to parse it ﹡ json_decode($string, true) turns the string into a JSON object.
API K /T ? ﹡ An API might tell you that you need a key or a key and token to use it. ﹡ API keys are unique to accounts to determine sans credentials who’s using the account for security or account privilege purposes ﹡ Tokens are generally application specific and paired with a key
S H If you’re using file_get_contents, headers are added in the options parameter. This is where you usually add your key and/or token.
P API
W P ﹡ If you have a big spreadsheet or CSV but not time to DIY an application from scratch ﹡ Say, if you want to build some interactive charts on a webpage from spreadsheet data
P T ﹡ Google Sheets has its own API https://developers.google.com/sheets/api/ ﹡ Airtable a hosted database application that allows API access https://airtable.com
B Y O API
W H API? ﹡ Gets people to engage with your application ﹡ You may want to access some of your data asynchronously from within the application ﹡ Building mobile apps
W Y N ﹡ A database of information you want to access in whole or in part ﹡ A publicly-accessible PHP file that you can point requests to (that’s it!)
S H To send a response as JSON, before outputting your object, you need to send a content-type header
R JSON If your data can be put into an array or object, you can pass it through the json_encode function and echo the result after the header. If your content isn’t conveniently available in that form, you can also manually format it: https://en.wikipedia.org/wiki/JSON#Data_types,_syntax _and_example
H I API K ﹡ Each key should be unique ﹡ Store keys in user records and query for a match ﹡ You can do this manually for small applications, or automatically on account creation ﹡ An API key is like a password, so it should be possible to issue a new one
API f O P S ff ‘
T E fP API ﹡ Big tech companies keep deprecating APIs. Why? ﹡ To force traffic into their own channels ﹡ To prevent users from getting around ads ﹡ In response to security holes being discovered
W S ﹡ Gets the content of an HTML page and parses it as XML nodes ﹡ Classes such as DOMDocument can navigate these nodes and return the content you want ﹡ More laborious and less reliable (esp. since page layouts can change)
⚠M W ⚠ ﹡ This might be against the terms of service of a website ﹡ This can also be kind of rude if you’re using up all of a site’s bandwidth by scraping the content ﹡ You might get rate-limited or your script may get blocked, or your account might get suspended
C J ﹡ Polite way to fetch data: on specified intervals, rather than than on page load ﹡ The crontab (“cron table”) runs programs on scheduled intervals (see crontab.guru for formatting help) ﹡ You can use the scheduler to import data to a database by script a few times a day so you don’t overload services
N I S ﹡ This is not a solution for a production application ﹡ If a site you use doesn’t have a public API, consider getting in touch to ask if that’s on the roadmap or could be ﹡ If it’s an open-source project, consider putting in a pull request to add API support
Now: go forth and build things! @carlymho @carly@kitty.town carlymho.com
Application Programming Interfaces, or APIs, are a great way to bring more data into your app or transform the data you already have by connecting it to other services—and a great way to get more people to engage with your application if you build one yourself. A whirlwind tour of some ways to get data from some well-documented sources, some tools to help build an API or proof-of-concept very quickly, and how to get data from a site that doesn’t have its own API.
for free. You
can too.