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Test objects for blankness with this one little trick!

Posted in Rails

Photo by Dylan Gillis on Unsplash
Photo by Dylan Gillis on Unsplash

Rails adds a lot of syntactic sugar to plain old Ruby. A lot of this is wrapped up in the ActiveSupport module. If you work with Rails, and have not read ActiveSuport core_ext from cover to cover, stop now, and go do it. Go on, I'll wait.

OK, I sense a few lightbulbs coming on out there! "So thats why ..."

It seems most Rails folks know about (and use) Object#blank? and Object#present?. These are handy ways to test if something is, well, blank or not. Ruby thinks nil is false, which is great, but when dealing with web apps and user entered data, you might get an empty string or a bunch of space characters, which you also want to think of as false, perhaps so you can set a default value or something. Continually having to check for different types of blankness is annoying, so instead you can use Object#blank? = params[:country].blank? ? 'USA' : params[:country]
# or, alternatively = params[:country].present? ? params[:country] : 'USA'

Now, that still looks a bit ugly, to a rubyist's eyes, so we can use Object#presence (github) to clean it up even more: = params[:country].presense || 'USA'

#presence will either return the value if it is not blank, OR nil. This also works with arrays and hashes as well.

Its a small thing, but neatly encapsulates a common pattern, and isn't that pretty much what we get paid to do all day?