Cassiopeia Documentation

What is Cassiopeia?

Cassiopeia (which we fondly call Cass) is a framework for pulling and working with data from the Riot API. Cass differentiates itself from other API wrappers by taking a page from one of Cassiopeia’s quotes, “I’ll take care of everything.” Our main goal is to make your life (and ours) as developers easy.

Cass is composed of three key pieces:

  1. An interface for pulling data from the Riot API.

  2. A type system of classes for holding and working with the data pulled from Riot.

  3. Caches and databases to temporarily and permanently store that data.

Together, these three pieces provide the user experience we desire. Scroll down for a quick example of how Cass works, what Cass does for you as a user, and information about contributing.

Why use Cass?

  • An excellent user interface that makes working with data from the Riot API easy and fun.

  • “Perfect” rate limiting.

  • Guaranteed optimal usage of your API key.

  • Built in caching and (coming) the ability to easily hook into a database for offline storage of data.

  • Extendability to non-Riot data. Because Cass is a framework and not just an API wrapper, you can integrate your own data sources into your project. Cass already supports Data Dragon and the champion.gg API in addition to the Riot API.

  • Dynamic settings so you can configure Cass for your specific use case.

An Example

We will quickly and efficiently look up the champion masteries for the summoner “Kalturi” (one of the developers) and print the champions he is best at. If you just want a quick look at how the interface looks, feel free to just read these three lines and skip the explanation. The explanation explains how the three bullet points above fit together and allow this code to be run.

kalturi = Summoner(name="Kalturi")
good_with = kalturi.champion_masteries.filter(lambda cm: cm.level >= 6)
print([cm.champion.name for cm in good_with])

# At the time of writing this, this prints:
["Vel'Koz", 'Blitzcrank', 'Braum', 'Lulu', 'Sejuani']

The above three lines are relatively concise code, and if you know what lambdas and list comprehensions are then it will likely be readable. However, there is a deceptive amount of logic in these three lines, so let’s break it down. (If you don’t understand everything immediately, don’t worry, that’s why you’re using Cass. You don’t have to understand how everything works behinds the scenes, you just get to write good code.)

kalturi = Summoner(name="Kalturi")

First, we create a summoner with a name and id. Note that creating kalturi doesn’t trigger a call to the Riot API – it merely instantiates a Summoner object with a name and id.

... = kalturi.champion_masteries ...

Next we ask for the champion masteries for kalturi by running kalturi.champion_masteries. This creates an un-instantiated list which will contain champion masteries if any item in it is accessed.

good_with = kalturi.champion_masteries.filter(lambda cm: cm.level >= 6)

Third, the .filter method is called on the list of champion masteries. filter is a python built-in that operates on a list and filters the items in it based on some criteria. That criteria is defined py the lambda function we pass in.

A lambda is a quick way of defining functions in-line without using the def statement. In this case, lambda cm: takes in an object and assigns it to the variable cm, then it returns cm.level > 6. So this lambda will return True for any champion mastery whose mastery level is greater than or equal to 6.

The .filter(lambda cm: cm.level > 6) therefore operates on the list of champion masteries. When the list is iterated over, the champion masteries are queried. This requires a summoner id, which is pulled from kalturi.id, and the Riot API is queried for Kalturi’s champion masteries. With the champion mastery data pulled, .filter then filters the list looking for all champion masteries with mastery level 6 or higher.

print([cm.champion.name for cm in good_with])

Finally, the third line prints a list of the champion names for those champions.

Together these three lines illustrate the concise user interface that Cass provides, the way in which the data can be used, when the data is pulled (queried).

Contributing

Contributions are welcome and we have an entire page devoted to ways in which you can help us with Cass.