using multiple joins in queries

[John Merlino]

I have this query:

Report.
joins(:alerts).
joins(:alert_code).
where(:unit_id => unit_id).
where{time < my{self.time}}.
where("alert_codes.name LIKE ?", "%Inside virtual
fence%").
order("reports.time DESC").first

Basically, it breaks:

ActiveRecord::ConfigurationError (Association named 'alert_code' was
not found; perhaps you misspelled it?):


My associations look like this:

report has_many alerts
alert belongs_to :alert_code, :foreign_key => :code

I am trying to get the first report whose alerts belongs to alert_code
whose name is "inside virtual fence". So there are 3 associations
here. Trying to establish the connection.

[Rob Biedenharn]

On Mar 20, 2013, at 6:04 PM, John Merlino wrote:

> I have this query:
>
> Report.
> joins(:alerts).
> joins(:alert_code).

I think that you're looking for 'includes' rather than 'joins' for these associations.

Report.includes({:alerts => :alert_code}).

To use joins, you would have to supply more SQL-ish clauses, not symbols for the associations.

http://apidock.com/rails/v3.2.8/ActiveRecord/QueryMethods/joins
http://apidock.com/rails/v3.2.8/ActiveRecord/QueryMethods/includes

-Rob

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[Frederick Cheung]

On Thursday, March 21, 2013 2:33:24 AM UTC, Rob Biedenharn wrote:

On Mar 20, 2013, at 6:04 PM, John Merlino wrote:

> I have this query:
>
> Report.
>                    joins(:alerts).
>                    joins(:alert_code).

I think that you're looking for 'includes' rather than 'joins' for these associations.

Report.includes({:alerts => :alert_code}).

To use joins, you would have to supply more SQL-ish clauses, not symbols for the associations.

joins accepts either association names or sql clauses. When passing association names the syntax is the same as for includes, in particular you have to specify nested associations as a hash (as you have done).

Fred