Rails 4 has_and_belongs_to_many specific order

rubyonrails-talk
1

I’m trying to set a specific order to an association, but I keep getting the default scope order definition.

What am I missing?

class Pattern < ActiveRecord::Base

default_scope { order(‘sort, title’) }

has_and_belongs_to_many :children,

:class_name => 'Pattern', 

:join_table => 'patterns_patterns',

:association_foreign_key => 'child_id',

:foreign_key => 'parent_id',

:order => 'patterns_patterns.updated_at'

end

SELECT “patterns”.* FROM “patterns” INNER JOIN “patterns_patterns” ON “patterns”.“id” = “patterns_patterns”.“child_id” WHERE “patterns_patterns”.“parent_id” = ? ORDER BY sort, title [[“parent_id”, 1]]

2

I tend to avoid default_scope for exactly this reason, the results are not always obvious. I prefer to use named scopes or specify the order explicitly. Then you have better control of what is going on. Many believe default scopes are evil. I believe you can override it using reorder.

Colin

3

Which Rails version are you running? There were a substantial number of issues with default_scope fixed in 4.0 and 4.1.

–Matt Jones

4

Hi Colin, thank you for your answer. I just realized that my problem is bigger than that. I removed the default_scope and my query now is “orderbyless”.

SELECT “patterns”.* FROM “patterns” INNER JOIN “patterns_patterns” ON “patterns”.“id” = “patterns_patterns”.“child_id” WHERE “patterns_patterns”.“parent_id” = ? [[“parent_id”, 7]]

Why the order is been ignored?

class Pattern < ActiveRecord::Base

has_and_belongs_to_many :children,

:class_name => 'Pattern', 

:join_table => 'patterns_patterns',

:association_foreign_key => 'child_id',

:foreign_key => 'parent_id',

:order => 'patterns_patterns.updated_at'

end

Quinta-feira, 15 de Maio de 2014 5:34:26 UTC-3, Colin Law escreveu:

5

Hi Matt,

My Rails version is 4.1.0.

Quinta-feira, 15 de Maio de 2014 10:11:01 UTC-3, Matt Jones escreveu:

6

Hi Colin, thank you for your answer. I just realized that my problem is bigger than that. I removed the default_scope and my query now is “orderbyless”.

SELECT “patterns”.* FROM “patterns” INNER JOIN “patterns_patterns” ON “patterns”.“id” = “patterns_patterns”.“child_id” WHERE “patterns_patterns”.“parent_id” = ? [[“parent_id”, 7]]

Why the order is been ignored?

class Pattern < ActiveRecord::Base

has_and_belongs_to_many :children,

:class_name => 'Pattern', 

:join_table => 'patterns_patterns',

:association_foreign_key => 'child_id',

:foreign_key => 'parent_id',

:order => 'patterns_patterns.updated_at'

end

The order option was removed a while back - things that change the query should be done in a scope lambda instead:

has_and_belongs_to_many :children, → { order(:something) }, …

–Matt Jones

7

Thank you Matt,

It kind for work. It added a new order item instead of replace it.

class Pattern < ActiveRecord::Base

default_scope { order(‘sort, title’) }

has_and_belongs_to_many :children,

-> { order('patterns_patterns.id') },

:class_name => 'Pattern', 

:join_table => 'patterns_patterns',

:association_foreign_key => 'child_id',

:foreign_key => 'parent_id'

end

**… ORDER BY sort, title, patterns_patterns.id **

Any idea?

Sexta-feira, 16 de Maio de 2014 9:27:18 UTC-3, Matt Jones escreveu:

8

Solved.

If anybody is having the same issue, the answer is to use “reorder” instead of order.

Thank you all.

Sexta-feira, 16 de Maio de 2014 19:38:15 UTC-3, Henrique Vilela escreveu:

9

I think that is what I said in my first reply.

Colin