On Tuesday, May 1, 2012 11:52:49 AM UTC-7, Joel VanderWerf wrote:
>
>
> Is it possible to marshal a dataset? I really mean the Dataset instance
> itself, not the result set.
>
> On unmarshalling, the dataset would have to be reassociated with the
> database somehow.
>
> To be precise, this is what I wanted:
>
> require 'sequel'
>
> DB = Sequel.sqlite
>
> DB.create_table :t do
> primary_key :id
> float :f
> end
>
> q = DB[:t].filter{ f > 3 }
> puts q.sql # => SELECT * FROM `t` WHERE (`f` > 3)
>
> s = Marshal.dump(q)
> # fails here, because there's a proc in q, and a database
>
Well, the proc isn't the same proc you passed to filter, since that proc is
eagerly evaluated. The Database object has many procs in it, though.
>
> qq = Marshal.load(s)
> # qq.connect DB ?
> puts qq.sql # => SELECT * FROM `t` WHERE (`f` > 3)
>
>
Dataset and Database instances are not designed to be marshalable. This
may work for your use case:
q.db = nil
s = Marshal.dump(q)
qq = Marshal.load(s)
qq.db = DB
I don't guarantee this works for all datasets, though. Many adapters use
datasets that are instances of anonymous classes, for example.
Jeremy
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