Active Record question

[j...@via.net]

class Asset < ActiveRecord::Base

  belongs_to :site

  # class variable :name

end

class Site < ActiveRecord::Base

  has_many :assets

  # class var x, y, z

end

Is there a dynamic finder that will traverse the inner join:

e.g. Site.find_by_asset_name("xyzzy")

Can I get a list of sites where asset.name == "BAZ"

Can this be done in AR or do I have to resort to SQL?

Thanks,

Joe

[Vineeth B S]

Ransack

https://github.com/activerecord-hackery/ransack

Seems like a promising for your usecase. Take a look at it.

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Regards
Vineeth B S

[Colin Law]

On 13 July 2015 at 01:10, j...@via.net <j...@via.net> wrote:
> class Asset < ActiveRecord::Base
> belongs_to :site
>
> # class variable :name
>
> end
>
> class Site < ActiveRecord::Base
> has_many :assets
>
> # class var x, y, z
>
> end
>
> Is there a dynamic finder that will traverse the inner join:
>
> e.g. Site.find_by_asset_name("xyzzy")

Asset.where( name: 'xyzzy').site

>
> Can I get a list of sites where asset.name == "BAZ"

Site.joins(:assets).where(assets: {name: "BAZ"})

>
> Can this be done in AR or do I have to resort to SQL?

As you can see it can be done in AR. It is very rare to have to
resort to SQL in Rails. If you do it often means you have not
specified the associations correctly.

Have a look at the rails guide on ActiveRecord Querying, and the other
guides. In fact I suggest you start by working right through a good
tutorial such as railstutorial.org, which is free to use online. That
will show you the basics of Rails.

Colin

[tamouse pontiki]

A quick correction on Colin's suggestion:

On Mon, Jul 13, 2015 at 2:44 AM, Colin Law <cla...@gmail.com> wrote:

On 13 July 2015 at 01:10, j...@via.net <j...@via.net> wrote:
> class Asset < ActiveRecord::Base
>   belongs_to :site
>
>   # class variable :name
>
> end
>
> class Site < ActiveRecord::Base
>   has_many :assets
>
>   # class var x, y, z
>
> end
>
> Is there a dynamic finder that will traverse the inner join:
>
> e.g. Site.find_by_asset_name("xyzzy")

Asset.where( name: 'xyzzy').site

Asset.find_by(name: 'xyzzy').site

Because .where returns a collection, .find_by returns the first one found.

Asset.where(name: 'xyzzy').first = Asset.find_by(name: 'xyzzy')

(I make this same mistake a lot for some reason.)

[Colin Law]

On 13 July 2015 at 19:20, tamouse pontiki <tamous...@gmail.com> wrote:
> A quick correction on Colin's suggestion:
>
> On Mon, Jul 13, 2015 at 2:44 AM, Colin Law <cla...@gmail.com> wrote:
>>
>> On 13 July 2015 at 01:10, j...@via.net <j...@via.net> wrote:
>> > class Asset < ActiveRecord::Base
>> > belongs_to :site
>> >
>> > # class variable :name
>> >
>> > end
>> >
>> > class Site < ActiveRecord::Base
>> > has_many :assets
>> >
>> > # class var x, y, z
>> >
>> > end
>> >
>> > Is there a dynamic finder that will traverse the inner join:
>> >
>> > e.g. Site.find_by_asset_name("xyzzy")
>>
>> Asset.where( name: 'xyzzy').site
>
>
> Asset.find_by(name: 'xyzzy').site
>
> Because .where returns a collection, .find_by returns the first one found.
>
> Asset.where(name: 'xyzzy').first = Asset.find_by(name: 'xyzzy')

Good call, you are right. Thanks.

Colin