Why won't this datamapper object save?

1
votes

Here's the model:

class Target
  include DataMapper::Resource

  property :id, Serial
  property :owed, Integer, :default => 0, :required => true
  property :served, Integer, :default => 0, :required => true

  def go
    @owed -= 1
    @served += 1
    save
  end
end

When I do this:

t = Target.first
t.go

It doesn't seem to update the database. Any ideas?

2
ruby-on-railsrubysinatradatamapper

2 Answers

4
votes

The resource isn't saving because DataMapper doesn't know that the owed and served properties have been changed. #save will only save the resource, if the resource is considered dirty by DataMapper.

Instead, change the values of self.owed and self.served, which will cause a state change within the resource, which will mark the resource as dirty and allow #save to trigger. Additionally, you can simplify the go method using #update:

def go
  update(:owed => self.owed - 1, :served => self.served + 1)
end
3
votes

You need to use self.owed and self.served instead:

def go
  self.owed -= 1
  self.served += 1
  save
end