Have you tried
has_one :primary_asset, :class_name=>"Asset", :order=>"position"
On Dec 8, 4:59 am, Max Williams <[EMAIL PROTECTED]>
wrote:
> A little background: in our schema, Resource has_many :assets, through a
> join table called items.
>
> Whenever we show a resource, we also show a thumbnail for its first
> associated asset. Currently, this means that we're doing a lot of sql
> action in the view: for example, a partial like this might be repeated
> 100 times:
>
> ....
> <% asset = resource.assets.first %>
> <%= image_tag asset.name, asset.path %>
> ...
>
> Obviously doing loads of little queries in the view isn't good: what
> i'd like to do is somehow eager-load that first asset with the include
> option. We tried making a method called 'primary_asset' which returns
> the first asset for a resource, but that can't be "include"d: i think
> that in order to include it i need to set it up as an association.
> Which leads me to my actual question: how do i set up a has_one
> association to return only the first asset from the collection of
> associated assets?
>
> has_one doesn't seem to have an 'sql' option, otherwise i'd just do
> something like
>
> has_one :primary_asset, :class_name => "Asset", :sql => "SELECT
> assets.* FROM assets INNER JOIN items ON assets.id = items.asset_id
> WHERE ((items.resource_id = #{id})) ORDER BY position LIMIT 1"
>
> Can anyone see how i can set this up? I'm using rails 2.0.2.
>
> thanks, max
> --
> Posted viahttp://www.ruby-forum.com/.
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