YAML data type sometimes badly tracks changes

[datamapper]

YAML data type sometimes badly tracks changes

[solnic]

Currently DataMapper only tracks changes caused by calling the mutator methods, not changes using the reference to the value internally.

So for example, if you have a String, and you set the user.name using user.name = "gondar", and then later you use user.name << "other" to append to the String, DataMapper isn’t going to notice the change since you modified the value that it has a reference to.

DataMapper used to track this sort of change, but it incurred a large overhead and was needlessly complex. I removed it until we could figure out a better approach.

I suppose it may be possible if we take a snapshot of the object attributes’ Object#hash values when it is loaded, and then compare those when it comes time to save the object. I’m not yet sure what sort of overhead this will have, but it may be worth looking into later.

For now I am going to mark this as a "suggestion" and we will revisit it prior to 1.0

by Dan Kubb (dkubb)

[solnic]

I wish this ticket were higher on google, but here’s a workaround for anyone else who, like me, finds this type not very useful without this feature. Unfortunately, it will always save the YAML property if it has been loaded at all.

before :save, :dump_yaml

def dump_yaml
  self.yaml_prop = YAML.dump(self.yaml_prop) if attribute_loaded? :yaml_prop
end

by blavender (at gmail)

[solnic]

I added a pending spec for this and sent a pull request, see http://github.com/bhuga/dm-more/commit/e09a0579290a7036ee19f4d9f8c173ebad2a9654

by blavender (at gmail)

[jpr5]

Note that pull request 33 (#33) would fix this use case.

[dkubb]

@jpr5's pull request was merged which solves this problem. Closing this ticket.

If the problem still persists please add a comment to this ticket, otherwise enjoy!