Rails - May 2008 - setting find conditions to equal a value 2 tbl joins away

ok here is my initial table setups:

ITEM TYPES
id
name

ITEMS
id
name
item_type_id

TOOLS
id
item_id
parent_id

class Tool < ActiveRecord::Base
    belongs_to :item

    def name
      item.name
    end

    def item_type
      item.item_type.name
    end
end

class Item < ActiveRecord::Base
    belongs_to :item_type
end

I can use the following tool.item_type  or item.item_type.name to get
the name of the item type but i can not get this query to work:

@tools = Tool.find(:all, :include => :item, :conditions => { :item_type
=> "Instrument"}, :order => :name)

I am getting Unknown column ''tools.item_type'' even though
item_type is
defined in the model.  any ideas?

thanks!
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On 21 May 2008, at 00:05, Scott Kulik wrote:
>
> class Tool < ActiveRecord::Base
>    belongs_to :item
>
>    def name
>      item.name
>    end
>
>    def item_type
>      item.item_type.name
>    end
> end
>
> class Item < ActiveRecord::Base
>    belongs_to :item_type
> end
>
> I can use the following tool.item_type  or item.item_type.name to get
> the name of the item type but i can not get this query to work:
>
> @tools = Tool.find(:all, :include => :item, :conditions =>  
> { :item_type
> => "Instrument"}, :order => :name)
>
> I am getting Unknown column ''tools.item_type'' even though
item_type is
> defined in the model.  any ideas?
>
conditions need to reference database columns. methods you''ve defined  
don''t count.
:conditions => {''items.item_type'' =>
''Instrument''} should work.

Fred
> thanks!
> -- 
> Posted via http://www.ruby-forum.com/.
>
> >

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Frederick Cheung wrote:
> On 21 May 2008, at 00:05, Scott Kulik wrote:
> 
>>    end
>> { :item_type
>> => "Instrument"}, :order => :name)
>>
>> I am getting Unknown column ''tools.item_type'' even
though item_type is
>> defined in the model.  any ideas?
>>
> conditions need to reference database columns. methods you''ve
defined
> don''t count.
> :conditions => {''items.item_type'' =>
''Instrument''} should work.
> 
> Fred
ah ok thanks.  since item_type isn''t directly a database column but 
item_type_id is i can get this statement working:
    @tools = Tool.find(:all, :include => :item, :conditions => 
{''items.item_type_id'' => 2}, :order => :name)

but what if i want to go one level deeper like

    @tools = Tool.find(:all, :include => :item, :conditions => 
{''items.item_types.name'' =>
''Instrument''}, :order => :name)

or

    @tools = Tool.find(:all, :include => :item, :include => :item_type, 
:conditions => {''item_types.name'' =>
''Instrument''}, :order => :name)

the first give me an error saying Unknown column
''items.item_types.name''
the second gives me the error Association named ''item_type''
was not
found.

thanks for the help so far.  i think i''m almost there!
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On 21 May 2008, at 00:46, Scott Kulik wrote:
>
> ah ok thanks.  since item_type isn''t directly a database column
but
> item_type_id is i can get this statement working:
>    @tools = Tool.find(:all, :include => :item, :conditions =>
> {''items.item_type_id'' => 2}, :order => :name)
>
> but what if i want to go one level deeper like
>
>    @tools = Tool.find(:all, :include => :item, :conditions =>
> {''items.item_types.name'' =>
''Instrument''}, :order => :name)
>
> or
>
>    @tools = Tool.find(:all, :include => :item, :include =>
:item_type,
> :conditions => {''item_types.name'' =>
''Instrument''}, :order => :name)
>
> the first give me an error saying Unknown column  
> ''items.item_types.name''
> the second gives me the error Association named
''item_type'' was not
> found.
>

There''s 2 separate things going on here. The first is including/ 
joining the right tables (by the way, do you need :include or  
is :joins enough)
if you need to join item and then join item_types onto that then you  
need to do :include => {:item => :item_type}.
The second bit is the condition, where you just need to provide the  
disambiguated column name ie {''item_types.name'' =>
''Instrument''}

Fred

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