i would post it in the rails core group.
On Mar 15, 6:12 am, Zyclops <[email protected]> wrote:
> I'm not satisfied with how rails currently handles finds accross
> active record models, and want to see if there's a waywe can improve
> it.
>
> The ability to generate dynamic search criteria from forms that search
> accross models can be quite difficult except in the simplest cases.
> The main cause of this is because as a developer you have to work out
> what the table name is going to be called before you are able to use
> it.
>
> Here is an example:
>
> class Person < ActiveRecord::Base
>
> # Everybody has a home address
> belongs_to :home_address,
> :class_name => 'Address',
> :foreign_key => 'home_address_id'
>
> # Only some people have a work address
> belongs_to :work_address,
> :class_name => 'Address',
> :foreign_key => 'work_address_id'
> end
>
> class Address < ActiveRecord::Base
> end
>
> Lets say we have a search panel, that allows you to filter on home
> address street name, and work address street name and the user may or
> may not use these search options.
>
> # A search for the home address 22
> Person.find(:all, :joins =>
> [:home_address, :work_address], :conditions => {:address =>
> {:street_no => 22}})
>
> # A search for the work address 22
> Person.find(:all, :joins =>
> [:work_address, :home_address], :conditions => {:address =>
> {:street_no => 22}})
> #Notice that the order of the joins affects what the conditions hash
> applies too. I believe this unintuitive.
>
> # I think a better system would be to use the names of the
> relationships to dictate the search criteria
> # This would stop the user having to guess what the join table is
> called.
>
> Person.find(:all, :joins =>
> [:work_address, :home_address], :conditions => {:home_address =>
> {:street_no => 22}})
>
> # If this could be developed I would think we'd need to cover these
> cases:
> # 1. Eager loading using inner join
> Person.find(:all, :joins =>
> [:work_address, :home_address], :conditions => {:home_address =>
> {:street_no => 22}})
>
> # 2. Eager loading using left join
> # Notice that the home_address has conditions specified so in this
> case we might want to enforce a left join
> Person.find(:all, :include =>
> [:work_address, :home_address], :conditions => {:home_address =>
> {:street_no => 22}})
>
> # 3.No eager loading specified (would we force a join because of the
> conditions specified?)
> Person.find(:all, :conditions => {:home_address => {:street_no =>
> 22}})
>
> # 4. Custom SQL for each nesting, so that you can use any sql but not
> have to explicitly know the name of the table
> Person.find(
> :all,
> :joins => :home_address
> :conditions => [
> {:age => 22},
> # This would currently conflict with the currect nested hash
> since
> {:home_address => ['home_address.street_name LIKE ?', 'Dougla%']}
> ]
> )
>
> # 1. Joins
> # SELECT *
> # FROM people
> # JOIN addresses home_address ON (people.home_address_id =
> home_address.id)
> # WHERE people.age = 22 AND
> # home_address.street_name LIKE 'Dougla%'
>
> # 2. Left Joins (:include)
> # SELECT *
> # FROM people
> # WHERE people.age = 22
> #
> # SELECT *
> # FROM addresses home_address
> # WHERE home_address.street_name LIKE 'Dougla%'
> # AND home_address.id IN (1,2,3,4,5,6,7,8,9,10)
>
> I'd like to hear your thoughts and ideas on any inherent problems with
> getting this implemented, or design improvements.
>
> It's only an idea at this stage, but I'd like to develop it so that
> developing complex dynamic searches using rails
> becomes trivial.
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