DataMapper won't save/update object if called in #each block I'm sure I'm doing something übern00b here (as I am a DM n00b).

model.rb

instances = Model.all

# If I try to perform this on all the instances, all return true but the changes are not persisted.

instances.each do |instance|
    desc = instance.description
    desc.gsub!(/some\swords/, '')
    instance.update(:description => desc) # doesn't work
    instance.description = desc
    instance.save # doesn't work and returns true.
end

# Now if I go look through the instances with another call to #all and put the description nothing has changed.

Model.all.each{|model| puts model.description }

# This works for changing the description and persists it, but only if I don't call it in the #each block
# on a collection... ID = a valid integer id.

desc = Model.get(ID).description
m = Model.get(ID)
desc.gsub!(/some\swords/, '')

Model.get(ID).update(:description => desc)

# OR #

m.description = desc
m.save