View Source Credo.Check.Warning.MapGetUnsafePass (Credo v1.7.7)


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This check has a base priority of normal and works with any version of Elixir.


Map.get/2 can lead into runtime errors if the result is passed into a pipe without a proper default value. This happens when the next function in the pipe cannot handle nil values correctly.


%{foo: [1, 2 ,3], bar: [4, 5, 6]}
|> Map.get(:missing_key)
|> Enum.each(&IO.puts/1)

This will cause a Protocol.UndefinedError, since nil isn't Enumerable. Often times while iterating over enumerables zero iterations is preferable to being forced to deal with an exception. Had there been a [] default parameter this could have been averted.

If you are sure the value exists and can't be nil, please use Map.fetch!/2. If you are not sure, Map.get/3 can help you provide a safe default value.

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