Re: [Rails] Re: Relations with find_each

[Colin Law]

On 8 June 2012 16:44, Max Reznichenko <max.rezniche...@gmail.com> wrote:
>> order.line_items != LineItem.where(:order_id => order.id)
>
> Let me rephrase Robert's words.
> The key difference here is, that LineItem.where(:order_id => order.id)
> doesn't fire the sql and returns ActiveRecord::Relation object.
> While the order.line_items runs SQL and returns the Array of records.
> The purpose of it is that u can change the resulting SQL and do the
> method chaining.
>
> Try next:
> line_items_by_order_id = LineItem.where(:order_id => order.id) # =>
> object of ActiveRecord::Relation class
> ordered_line_items_by_order_id = LineItem.where(:order_id =>
> order.id).order(:updated_at) # => object of ActiveRecord::Relation
> class
> ordered_line_items_by_order_id_with_positive_price =
> LineItem.where(:order_id =>
> order.id).order(:updated_at).where("line_items.price > ?", 20) # =>
> object of ActiveRecord::Relation class
> # ... and so on
> # where
> order.line_items # returns [LineItem, LineItem ...] array

It is noteworthy that one can still do
order.line_items.where( some condition )
even though order.line_items appears to be an Array.

Colin

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