On December 3, 2018 at 09:23:12, Jeremy Evans (jeremyeva...@gmail.com)
wrote:
On Monday, December 3, 2018 at 8:08:21 AM UTC-8, Jeremy Hinegardner wrote:
>
> Hey all,
>
> I'm working with a legacy database and looks like our best strategy for
> managing things is going to be using Datasets and Database directly (lots
> of non-trivial queries for the domain/business objects) and I'd like to do
> something like `DB.fetch(big_sql_query, map_to: EntityClass) {
> |entity_instance| ... }` or `DB[sql].all_mapped_to(EntityClass) # [
> entity_instance, entity_instance ... ]`. Something along those lines, open
> to any and all suggestions. I did some searching and didn't find exactly
> what I was looking for as an existing extension or in the core Sequel
> documentation.
>
> The closest I've found in this realm (and used before) is from the
> github-ds gem where you can map complex SQL to ActiveRecord instances -
> https://github.com/github/github-ds/blob/312b43b3d96bb376b87bc5e05045c3
> 06f40f2623/lib/github/sql.rb#L208-L222
>
> I'm thinking I've either missed the documentation or this is something
> trivial to implement as a Sequel extension. In the end this will probably
> end up being a light-weight Repository pattern build around Sequel.
>
> thoughts?
>
> -a different jeremy
>
Jeremy,
You can easily do this mapping for any Sequel dataset:
dataset = dataset.with_row_proc(lambda do |hash|
EntityClass.new(hash)
end)
dataset.all # => [<#EntityClass ...>, ...]
This (dataset row proc) is what Sequel::Model uses to make sure model
datasets return model instances.
Thanks Jeremy - that worked perfectly.
-jeremy
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