Re: [Rails] Active Record Query to select associated model values.

[Colin Law]

On 1 December 2012 14:08, sakthivel sekar <sakthive...@gmail.com> wrote:
> Hi,
> I have two models named Customer and Order.
>
> Customer < ActiveRecord::Base
> has_many :orders
> end
>
> Order < ActiveRecord::Base
> belongs_to :customer
> end
>
> Customer model has attributes like first_name and last_name. Order has
> customer_id along with other attributes.
>
> Now, I want Customer first_name for specific order. I can get it with
> following query.
>
> Customer.joins(:orders).where('orders.id = 1').select('first_name').

You are missing the fundamental nature of ActiveRecord associations.
If you have an order in, for example, @order then the customer is
@order.customer and if you want that customer's first_name then you
can say @order.customer.first_name. There is no need to mess about
with complex queries, such is the magic of Rails.

>
> But, how to get it along with attributes of order table also. Say, I want
> both customers first_name and orders table created_at value.
> When I try,
> Order.includes(:customer).select('orders.created_at, customers.first_name')
> this returns only order table records. What is the best way to select
> attributes of joined tables also with Active Record Query.

Have a look at the Rails Guide on ActiveRecord Associations (and the
other guides for that matter) and work right through a good tutorial
such as railstutorial.org (which is free to use online) and you will
be able to answer most of these questions yourself.

Colin

[sakthivel sekar]

Colin,

 Thanks for the reply. Yes, association makes this better and easy way. But I'm expecting a way apart from using association. I heard merge will do this, but I'm not sure. 

On Saturday, December 1, 2012 7:38:50 PM UTC+5:30, sakthivel sekar wrote:

Hi,
 I have two models named Customer and Order.

Customer < ActiveRecord::Base
has_many :orders
end

Order < ActiveRecord::Base
belongs_to :customer
end

Customer model has attributes like first_name and last_name. Order has customer_id along with other attributes.

Now, I want Customer first_name for specific order. I can get it with following query.

Customer.joins(:orders).where('orders.id = 1').select('first_name').

But, how to get it along with attributes of order table also. Say, I want both customers first_name and orders table created_at value.
When I try,
Order.includes(:customer).select('orders.created_at, customers.first_name')
this returns only order table records. What is the best way to select attributes of joined tables also with Active Record Query.

Thanks.

[Colin Law]

On 11 December 2012 17:08, sakthivel sekar <sakthive...@gmail.com> wrote:
> Colin,
> Thanks for the reply. Yes, association makes this better and easy way. But
> I'm expecting a way apart from using association. I heard merge will do
> this, but I'm not sure.

Why do you want to do it a way other than (as you say) the easiest?

Colin

>
>
> On Saturday, December 1, 2012 7:38:50 PM UTC+5:30, sakthivel sekar wrote:
>>
>> Hi,
>> I have two models named Customer and Order.
>>
>> Customer < ActiveRecord::Base
>> has_many :orders
>> end
>>
>> Order < ActiveRecord::Base
>> belongs_to :customer
>> end
>>
>> Customer model has attributes like first_name and last_name. Order has
>> customer_id along with other attributes.
>>
>> Now, I want Customer first_name for specific order. I can get it with
>> following query.
>>
>> Customer.joins(:orders).where('orders.id = 1').select('first_name').
>>
>> But, how to get it along with attributes of order table also. Say, I want
>> both customers first_name and orders table created_at value.
>> When I try,
>> Order.includes(:customer).select('orders.created_at,
>> customers.first_name')
>> this returns only order table records. What is the best way to select
>> attributes of joined tables also with Active Record Query.
>>
>> Thanks.
>>

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