Wednesday, October 22, 2014
Avantec,
That's actually an interesting question and you need a little knowledge of (1) How actual global variables work in Ruby, and (2) how the Rails boot process works, and (3) How A-Rels (ActiveRelation objects) work under the hood.
Typically what you are trying to do is not actually done. That's because data in the database changes, so 98% of the time you want the query to re-fire when it goes to look something up. To achieve that (not what you asked for), you typically use a scope on the model.
Caching the result is the next step-up from re-firing each time. That is often done with a memorized method, something like this:
class User
def self.all_admin_users
@all_admin_users ||= self.where(role: 'admin')
end
end
But note that even global variables are garbage collected when the current process ends (which in a web scenario is when the response is finished). So that will re-fire on the next web request.
If you truly want to load this in an initializer and have it persist across web requests, then you would indeed do that in an initializer during when the Rails app boots up. But that is rarely useful, since in order to make changes to that data you would have actually restart the entire web process. Generally it's better just to optimize the query, have it be a memorized method, and let it re-fire on each web request.
-Jason
On Oct 22, 2014, at 2:18 AM, Avantec Van <lists@ruby-forum.com> wrote:
Hi,
I've code like this
x_data = Model.where(column: 'xyz')
and I wanted to use 'x_data' everywhere like models, controllers,
helpers, etc.
I used in this way
module Global
X_DATA = Model.where(column: 'xyz')
end
but when using Global::X_DATA it is firing query every time.
Where should I write this to use it everywhere and query should not be
fired more than once.
add this in initializers is a good practice?
Please help.
Thanks in advance.
Avantec
--
Posted via http://www.ruby-forum.com/.
--
You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-talk+unsubscribe@googlegroups.com.
To post to this group, send email to rubyonrails-talk@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/rubyonrails-talk/126984f291818c4ea6cf113228caf379%40ruby-forum.com.
For more options, visit https://groups.google.com/d/optout.
----
Jason Fleetwood-Boldt
tech@datatravels.com
http://www.jasonfleetwoodboldt.com/writing
All material © Jason Fleetwood-Boldt 2014. Public conversations may be turned into blog posts (original poster information will be made anonymous). Email jason@datatravels.com with questions/concerns about this.
Jason Fleetwood-Boldt
tech@datatravels.com
http://www.jasonfleetwoodboldt.com/writing
All material © Jason Fleetwood-Boldt 2014. Public conversations may be turned into blog posts (original poster information will be made anonymous). Email jason@datatravels.com with questions/concerns about this.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment