Integrating a Function to Persist Records
Let’s learn to write a function that we can optionally use to save records to a database or file.
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For this feature, let’s go from the outside in, addressing the outer API layer first. That way, we can think about the shape of our external APIs.
Pulling a persistence function from the environment
In /lib/mastery.ex, we need to pull a persistence function from the environment to dictate the persistence mechanism, like this:
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@persistence_fn Application.get_env(:mastery, :persistence_fn)
That was easy enough. We pass in another argument, a function to optionally persist each new response. The responsibility of the function from Mastery’s perspective is to return a response. ...