Make strings blank based on boolean, Rails

Question

I've got a model, Photo, that has two options, is_photo or is_art, each with their own separate fields.

But, when one option is chosen I want the other option's fields to be reset into blank strings.

This is what I have:

photo.rb

before_save :reset_photo_options
before_save :reset_art_options

def reset_photo_options
  if self.is_art == 1
    self.resolution = ""
    self.camera = ""
  end
end

def reset_art_options
  if self.is_photo == 1
    self.tool = ""
    self.medium = ""
  end
end

However, if I fill out the is_photo fields and then change to is_art and fill those out all of the fields are saved.

How can I successfully reset the other option's fields?

There may be some other interactions we don't have visibility into; setting them manually. Make sure the compares are actually firing. If is_art and is_photo are actual DB fields I'd revisit that choice (maybe even STI, which is fine for simple usecases). — Dave Newton
– Dave Newton, Commented Feb 1, 2018 at 16:40

Michael Chaney · Accepted Answer · 2018-02-01 16:39:52Z

1

When dealing with mutually exclusive options like this, I always create a single field that has the type. With "enums" you can do something like this:

class Photo
  enum photo_style: [ :art, :photo ]
end

This gives you the ability to use similar methods:

photo.art?

that you would use with straight up booleans.

You can also use them in queries and such:

Photo.where(photo_style: :photo)

For your specific question, you can then roll the logic into a single callback:

before_save :reset_options

def reset_options
  if art?
    # do something
  elsif photo?
    # do something else
  end
end

More here:

http://api.rubyonrails.org/classes/ActiveRecord/Enum.html

answered Feb 1, 2018 at 16:39

Michael Chaney

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Comments

tadman · Accepted Answer · 2018-02-01 16:39:21Z

If these are proper boolean columns, at least as far as ActiveRecord is concerned, then you should be able to do this by using the ? method variant that returns a strict true or false value:

def reset_photo_options
  return unless self.is_art?

  self.resolution = nil
  self.camera = nil
end

def reset_art_options
  return unless self.is_photo?

  self.tool = nil
  self.medium = nil
end

Setting as nil is usually better than as empty string since a NULL column is a clear communicator that the field is not relevant and not set. Empty string could indicate missing data or no user input captured.

A further refactoring of this is to describe which fields go with what type:

SPECIFIC_FIELDS = {
  art: [
    :resolution,
    :camera
  ],
  photo: [
    :tool,
    :medium
  ]
}

def mask_off_irrelvant_options
  SPECIFIC_FIELDS.each do |category, fields|
    next unless (self.send(:"is_#{category}?"))

    fields.each do |name|
      self[name] = nil
    end
  end
end

This presumes things can be art and photo at the same time. If that's not the case then you don't need a series of independent booleans, you need one category field.

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