Module: Mongoid::Patchable

Defined in:
lib/mongoid/patchable.rb

Instance Method Summary collapse

Instance Method Details

#apply_patch(patch) ⇒ Object

Apply a patch this this document.

Currently assumes add_to_set and set operations will succeed.

TODO: is there a better way to ensure atomicity of multiple operations while avoiding race conditions from multiple clients?

it looks like

Preferences.collection.update(=> 1, => {‘follow_suggest_blacklist’ => 4, ‘$set’ => => 2})

would do this, but a) it needs to deal with multiple hunks acting on the same attribute and b) it looks like mongoid doesn’t support this ootb. more research needed…

TODO: handle numeric path segments



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# File 'lib/mongoid/patchable.rb', line 19

def apply_patch(patch)
  # compile operation information for verification
  ops = patch.hunks.map do |hunk|
    (obj, element) = hunk.resolve_path(self)
    [hunk, obj, element, obj.fields[element.to_s]]
  end

  if patch_ops_valid?(ops)
    # if something goes wrong here, raise an error to let the client
    # know the patch may be partially applied
    ops.each_with_index do |(hunk, obj, element, field), index|
      value = hunk.value
      case hunk.op
      when :add
        process_add(obj, field, element, value)
      when :replace
        process_replace(obj, field, element, value)
      when :remove
        process_remove(obj, field, element, value)
      else
        raise "Illegal operation #{hunk.op} in hunk #{index}"
      end
    end
    true
  end
end