thr3ads.net - Rails - includes and eager loading not working in simple setup [Mar 2012]

If this information is useful, please help other people find it:
Share via:

jenna_s

2012-Mar-31 20:28 UTC

includes and eager loading not working in simple setup

Hi,

I''m having trouble with a simple users-messages setup, where users can
send messages to other users. Here''s my class definition:

class Message < ActiveRecord::Base
  belongs_to :from_user, :class_name => ''User''
  belongs_to :to_user, :class_name => ''User''
end

class User < ActiveRecord::Base
  def messages(with_user_id)
    Message.where("from_user_id = :id AND to_user_id = :with_user_id
OR to_user_id = :id AND from_user_id = :with_user_id",
      { :id => id, :with_user_id => with_user_id })
      .includes(:from_user, :to_user)
      .order("created_at DESC")
  end
end

When I do some_user.messages(another_user.id), I want to retrieve the
conversation that some_user has with another_user. I do get back an
array of Messages, but it doesn''t include the eager loading of
from_user and to_user. What am I doing wrong? Am I forced to use
joins?

Thanks,
J

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

Peter Vandenabeele

2012-Mar-31 20:56 UTC

head link

Re: includes and eager loading not working in simple setup

On Sat, Mar 31, 2012 at 10:28 PM, jenna_s
<jenna.simmer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Hi,
>
> I''m having trouble with a simple users-messages setup, where users
can
> send messages to other users. Here''s my class definition:
>
> class Message < ActiveRecord::Base
>  belongs_to :from_user, :class_name => ''User''
>  belongs_to :to_user, :class_name => ''User''
> end
>
> class User < ActiveRecord::Base
>  def messages(with_user_id)
>    Message.where("from_user_id = :id AND to_user_id = :with_user_id
> OR to_user_id = :id AND from_user_id = :with_user_id",
>      { :id => id, :with_user_id => with_user_id })
>      .includes(:from_user, :to_user)
>      .order("created_at DESC")
>  end
> end
>
> When I do some_user.messages(another_user.id), I want to retrieve the
> conversation that some_user has with another_user. I do get back an
> array of Messages, but it doesn''t include the eager loading of
> from_user and to_user.
How many SQL queries do you see in the log for

messages = some_user.messages(another_user.id)

(I believe you should see 3 queries if from_user and to_user data
is present).

When asking later on:

messages.first.from_user

is it then launching an SQL for the individual from_user
at that time?
> What am I doing wrong? Am I forced to use
> joins?
It must be possible to get this working with .includes
as you tried.

HTH,

Peter

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

jenna_s

2012-Apr-02 02:14 UTC

head link

Re: includes and eager loading not working in simple setup

Hi Peter,

How did you know that?! Yes, indeed there are 3 SQL queries:

Message Load (0.5ms)  SELECT `messages`.* FROM `messages` WHERE
(from_user_id = 3 AND to_user_id = ''2'' OR to_user_id = 3 AND
from_user_id = ''2'') ORDER BY created_at DESC LIMIT 1
User Load (0.4ms)  SELECT `users`.* FROM `users` WHERE (`users`.`id` 2)
User Load (0.5ms)  SELECT `users`.* FROM `users` WHERE (`users`.`id` 3)

Why is that? I really expected one SQL statement. In fact I need one
SQL statement since I need to serialize and respond to in JSON. How
can I fix it?

Thanks so much,
Jenna

On Mar 31, 1:56 pm, Peter Vandenabeele
<pe...-jNuWw7i2w7syMbTcgqFhxg@public.gmane.org>
wrote:> On Sat, Mar 31, 2012 at 10:28 PM, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > Hi,
>
> > I''m having trouble with a simple users-messages setup, where
users can
> > send messages to other users. Here''s my class definition:
>
> > class Message < ActiveRecord::Base
> >  belongs_to :from_user, :class_name => ''User''
> >  belongs_to :to_user, :class_name => ''User''
> > end
>
> > class User < ActiveRecord::Base
> >  def messages(with_user_id)
> >    Message.where("from_user_id = :id AND to_user_id =
:with_user_id
> > OR to_user_id = :id AND from_user_id = :with_user_id",
> >      { :id => id, :with_user_id => with_user_id })
> >      .includes(:from_user, :to_user)
> >      .order("created_at DESC")
> >  end
> > end
>
> > When I do some_user.messages(another_user.id), I want to retrieve the
> > conversation that some_user has with another_user. I do get back an
> > array of Messages, but it doesn''t include the eager loading
of
> > from_user and to_user.
>
> How many SQL queries do you see in the log for
>
> messages = some_user.messages(another_user.id)
>
> (I believe you should see 3 queries if from_user and to_user data
> is present).
>
> When asking later on:
>
> messages.first.from_user
>
> is it then launching an SQL for the individual from_user
> at that time?
>
> > What am I doing wrong? Am I forced to use
> > joins?
>
> It must be possible to get this working with .includes
> as you tried.
>
> HTH,
>
> Peter
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

Frederick Cheung

2012-Apr-02 15:55 UTC

head link

Re: includes and eager loading not working in simple setup

On Apr 2, 3:14 am, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Hi Peter,
>
> How did you know that?! Yes, indeed there are 3 SQL queries:
>
> Message Load (0.5ms)  SELECT `messages`.* FROM `messages` WHERE
> (from_user_id = 3 AND to_user_id = ''2'' OR to_user_id = 3
AND
> from_user_id = ''2'') ORDER BY created_at DESC LIMIT 1
> User Load (0.4ms)  SELECT `users`.* FROM `users` WHERE (`users`.`id` >
2)
> User Load (0.5ms)  SELECT `users`.* FROM `users` WHERE (`users`.`id` >
3)
>
> Why is that? I really expected one SQL statement. In fact I need one
> SQL statement since I need to serialize and respond to in JSON. How
> can I fix it?
This is how include works by default. The loaded users are wired up to
the message objects for you. There is one query per association, so
you get the most benefit when there are multiple messages. The fact
that it takes multiple queries (or even whether you use :include at
all) has no effect on what the serialised json will look like.

You can force AR to use a joins based include strategy via eager_load
if you really want it to. (but like i said whether stuff is eagerly
loaded or not doesn''t impact the generated json)


Fred

>
> Thanks so much,
> Jenna
>
> On Mar 31, 1:56 pm, Peter Vandenabeele
<pe...-jNuWw7i2w7syMbTcgqFhxg@public.gmane.org> wrote:
>
>
>
>
>
>
>
> > On Sat, Mar 31, 2012 at 10:28 PM, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > > Hi,
>
> > > I''m having trouble with a simple users-messages setup,
where users can
> > > send messages to other users. Here''s my class
definition:
>
> > > class Message < ActiveRecord::Base
> > >  belongs_to :from_user, :class_name =>
''User''
> > >  belongs_to :to_user, :class_name => ''User''
> > > end
>
> > > class User < ActiveRecord::Base
> > >  def messages(with_user_id)
> > >    Message.where("from_user_id = :id AND to_user_id =
:with_user_id
> > > OR to_user_id = :id AND from_user_id = :with_user_id",
> > >      { :id => id, :with_user_id => with_user_id })
> > >      .includes(:from_user, :to_user)
> > >      .order("created_at DESC")
> > >  end
> > > end
>
> > > When I do some_user.messages(another_user.id), I want to retrieve
the
> > > conversation that some_user has with another_user. I do get back
an
> > > array of Messages, but it doesn''t include the eager
loading of
> > > from_user and to_user.
>
> > How many SQL queries do you see in the log for
>
> > messages = some_user.messages(another_user.id)
>
> > (I believe you should see 3 queries if from_user and to_user data
> > is present).
>
> > When asking later on:
>
> > messages.first.from_user
>
> > is it then launching an SQL for the individual from_user
> > at that time?
>
> > > What am I doing wrong? Am I forced to use
> > > joins?
>
> > It must be possible to get this working with .includes
> > as you tried.
>
> > HTH,
>
> > Peter
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

jenna_s

2012-Apr-02 21:03 UTC

head link

Re: includes and eager loading not working in simple setup

Ok... I had no idea. I always thought that if you have an
includes,that will automatically resolve to a join because otherwise
this might result in the N+1 problem. I guess I need to read up about
it some more.

One final question: when I return some_user.messages(another_user.id)
to json from my controller, I don''t get the from_user and the to_user:
format.json { render :json => { :conversation => @messages.as_json } }
returns
{"conversation":[{"message":
{"created_at":"2012-02-25T20:21:01Z","from_user_id":1,"id":
2,"message":"lion
king","to_user_id":3,"updated_at":null}},{"message":
{"created_at":"2012-02-25T20:21:01Z","from_user_id":3,"id":
9,"message":"this is
ninth","to_user_id":1,"updated_at":null}}]}

How can I force the from_user and to_user as part of each "message"?
(I guess I could have them returned as separate tags at the same level
as "conversation", but I was wondering if there''s a way to do
it
inside "message", e.g. {"message":
{created_at:...","id":"1","from_user":{"name":"Bob","age":"20",
etc.}}})

Thanks so much for all the help!

On Apr 2, 8:55 am, Frederick Cheung
<frederick.che...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> On Apr 2, 3:14 am, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> > Hi Peter,
>
> > How did you know that?! Yes, indeed there are 3 SQL queries:
>
> > Message Load (0.5ms)  SELECT `messages`.* FROM `messages` WHERE
> > (from_user_id = 3 AND to_user_id = ''2'' OR to_user_id
= 3 AND
> > from_user_id = ''2'') ORDER BY created_at DESC LIMIT 1
> > User Load (0.4ms)  SELECT `users`.* FROM `users` WHERE (`users`.`id`
> > 2)
> > User Load (0.5ms)  SELECT `users`.* FROM `users` WHERE (`users`.`id`
> > 3)
>
> > Why is that? I really expected one SQL statement. In fact I need one
> > SQL statement since I need to serialize and respond to in JSON. How
> > can I fix it?
>
> This is how include works by default. The loaded users are wired up to
> the message objects for you. There is one query per association, so
> you get the most benefit when there are multiple messages. The fact
> that it takes multiple queries (or even whether you use :include at
> all) has no effect on what the serialised json will look like.
>
> You can force AR to use a joins based include strategy via eager_load
> if you really want it to. (but like i said whether stuff is eagerly
> loaded or not doesn''t impact the generated json)
>
> Fred
>
>
>
>
>
>
>
>
>
> > Thanks so much,
> > Jenna
>
> > On Mar 31, 1:56 pm, Peter Vandenabeele
<pe...-jNuWw7i2w7syMbTcgqFhxg@public.gmane.org> wrote:
>
> > > On Sat, Mar 31, 2012 at 10:28 PM, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > > > Hi,
>
> > > > I''m having trouble with a simple users-messages
setup, where users can
> > > > send messages to other users. Here''s my class
definition:
>
> > > > class Message < ActiveRecord::Base
> > > >  belongs_to :from_user, :class_name =>
''User''
> > > >  belongs_to :to_user, :class_name =>
''User''
> > > > end
>
> > > > class User < ActiveRecord::Base
> > > >  def messages(with_user_id)
> > > >    Message.where("from_user_id = :id AND to_user_id =
:with_user_id
> > > > OR to_user_id = :id AND from_user_id = :with_user_id",
> > > >      { :id => id, :with_user_id => with_user_id })
> > > >      .includes(:from_user, :to_user)
> > > >      .order("created_at DESC")
> > > >  end
> > > > end
>
> > > > When I do some_user.messages(another_user.id), I want to
retrieve the
> > > > conversation that some_user has with another_user. I do get
back an
> > > > array of Messages, but it doesn''t include the eager
loading of
> > > > from_user and to_user.
>
> > > How many SQL queries do you see in the log for
>
> > > messages = some_user.messages(another_user.id)
>
> > > (I believe you should see 3 queries if from_user and to_user data
> > > is present).
>
> > > When asking later on:
>
> > > messages.first.from_user
>
> > > is it then launching an SQL for the individual from_user
> > > at that time?
>
> > > > What am I doing wrong? Am I forced to use
> > > > joins?
>
> > > It must be possible to get this working with .includes
> > > as you tried.
>
> > > HTH,
>
> > > Peter
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

Colin Law

2012-Apr-02 21:11 UTC

head link

Re: Re: includes and eager loading not working in simple setup

On 2 April 2012 22:03, jenna_s
<jenna.simmer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Ok... I had no idea. I always thought that if you have an
> includes,that will automatically resolve to a join because otherwise
> this might result in the N+1 problem. I guess I need to read up about
> it some more.
>
> One final question: when I return some_user.messages(another_user.id)
> to json from my controller, I don''t get the from_user and the
to_user:
> format.json { render :json => { :conversation => @messages.as_json }
}
> returns
> {"conversation":[{"message":
>
{"created_at":"2012-02-25T20:21:01Z","from_user_id":1,"id":
> 2,"message":"lion
king","to_user_id":3,"updated_at":null}},{"message":
>
{"created_at":"2012-02-25T20:21:01Z","from_user_id":3,"id":
> 9,"message":"this is
ninth","to_user_id":1,"updated_at":null}}]}
>
> How can I force the from_user and to_user as part of each
"message"?
> (I guess I could have them returned as separate tags at the same level
> as "conversation", but I was wondering if there''s a way
to do it
> inside "message", e.g. {"message":
>
{created_at:...","id":"1","from_user":{"name":"Bob","age":"20",
> etc.}}})
I think you can use the :include option of render :json to do that.

Colin

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

jenna_s

2012-Apr-03 05:41 UTC

head link

Re: includes and eager loading not working in simple setup

Great! Thanks everyone for the help.

On Apr 2, 2:11 pm, Colin Law
<clan...-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
wrote:> On 2 April 2012 22:03, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>
>
>
>
>
>
>
>
> > Ok... I had no idea. I always thought that if you have an
> > includes,that will automatically resolve to a join because otherwise
> > this might result in the N+1 problem. I guess I need to read up about
> > it some more.
>
> > One final question: when I return some_user.messages(another_user.id)
> > to json from my controller, I don''t get the from_user and the
to_user:
> > format.json { render :json => { :conversation =>
@messages.as_json } }
> > returns
> > {"conversation":[{"message":
> >
{"created_at":"2012-02-25T20:21:01Z","from_user_id":1,"id":
> > 2,"message":"lion
king","to_user_id":3,"updated_at":null}},{"message":
> >
{"created_at":"2012-02-25T20:21:01Z","from_user_id":3,"id":
> > 9,"message":"this is
ninth","to_user_id":1,"updated_at":null}}]}
>
> > How can I force the from_user and to_user as part of each
"message"?
> > (I guess I could have them returned as separate tags at the same level
> > as "conversation", but I was wondering if there''s a
way to do it
> > inside "message", e.g. {"message":
> >
{created_at:...","id":"1","from_user":{"name":"Bob","age":"20",
> > etc.}}})
>
> I think you can use the :include option of render :json to do that.
>
> Colin
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

Rails - Mar 2012 - includes and eager loading not working in simple setup

includes and eager loading not working in simple setup

Re: includes and eager loading not working in simple setup

Re: includes and eager loading not working in simple setup

Re: includes and eager loading not working in simple setup

Re: includes and eager loading not working in simple setup

Re: Re: includes and eager loading not working in simple setup

Re: includes and eager loading not working in simple setup