Short way to fetch data when a service should behave as "usual method"

[marian13]

It is really common to have the code like this:

# before
def show
  result = Static::ProcessParams[params: params]

  processed_params = result.success? ? result.data[:processed_params] : {}

  params.merge!(processed_params)

  super
end

This happens since the Standard config enforces a developer to check the result status.

Checking the result status is a good feature and we don't need to avoid it for sure.

But it can be hidden to not lose the focus when it does not play the main role:

# after
def show
  processed_params = Static::ProcessParams[params: params].fetch(:processed_params, {})

  params.merge!(processed_params)

  super
end

A new plugin creation for it won't be too hard, I suppose.

---

Complexity: Low

Hard Requirements:

• fetch should support the following signature - fetch(key, fallback).
• fetch should support the following signature - fetch(key, &block), where the block return value is a fallback.
• When the result is successful - fetch should return the data attribute by key (result.data[key]).
• When the result is an error - fetch should return the fallback value.
• When the result is a failure - fetch should return the fallback value.

Notes:

• result.data[key] already raises an exception when the status is not checked, so no need to introduce a new exception class.
• Two plugins should be created.
• The first one - with concern that introduces fetch with its default logic.
• Second one - with middleware that extends fetch logic (block).