On Tuesday, February 11, 2014 11:59:46 AM UTC-8, Jamie Hodge wrote:
>
> Mode code looks something like this. Surely there is a better way to be
> doing this, no?
>
> # model
>
> many_to_many :resources, join_table: :items
> one_to_many :items
> ...
>
> # association model
>
> dataset_module do
>
> def lock_version
> select_map(Sequel.qualify(model.table_name, :lock_version))
> end
> end
>
> # controller
>
> def dataset
> model.eager(:items, resources: { original: :proxies })
> end
>
> # view
>
> def etag
> [
> collection,
> collection.items_dataset,
> collection.resources_dataset,
> collection.originals_dataset,
> collection.proxies_dataset
> ].map(&:lock_version).join
> end
>
If you've already eager loaded all the values, it seems pointless to check
with the database to get the lock version. In addition to being
inefficient, it also creates a race condition, in that the etag created
won't match the eagerly loaded values displayed on the page if there are
modificaitons between the object retrieval and the etag call. I'd do
something like this:
def etag
a = [collection]
a << collection.map(&:items).flatten.uniq
a << collection.map(&:resources).flatten.uniq
a << a.last.map(&:original).uniq.compact
a << a.last.map(&:proxies).flatten.uniq
a.map(&:lock_version).join
end
Thanks,
Jeremy
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