Ruby on Rails

On 28 Mar 2013, at 21:24, Colin Law <clanlaw@googlemail.com> wrote:

> On 28 March 2013 19:35, Serguei Cambour <s.cambour@gmail.com> wrote:
>> Recently I discovered one thing I didn't even think about, or I believed it
>> to work absolutely differently.
>> So, to explain it, given the following models:
>>
>> class Project < AR
>> has_many :participants
>> end
>>
>> class Participant < AR
>> belongs_to :project
>> end
>>
>> Here is what is going in the console:
>>
>> irb(main):003:0> p=Project.create(:name=>'java')
>> ←[1m←[36m (0.0ms)←[0m ←[1mSAVEPOINT active_record_1←[0m
>> ←[1m←[35mSQL (43.0ms)←[0m INSERT INTO "projects" ("created_at", "name",
>> "updated_at") VALUES (?, ?, ?) [["
>> created_at", Thu, 28 Mar 2013 19:27:06 UTC +00:00], ["name", "java"],
>> ["updated_at", Thu, 28 Mar 2013 19:27:06
>> UTC +00:00]]
>> ←[1m←[36m (0.0ms)←[0m ←[1mRELEASE SAVEPOINT active_record_1←[0m
>> => #<Project id: 1, name: "java", created_at: "2013-03-28 19:27:06",
>> updated_at: "2013-03-28 19:27:06">
>> irb(main):004:0> p.participants
>> ←[1m←[35mParticipant Load (0.0ms)←[0m SELECT "participants".* FROM
>> "participants" WHERE "participants"."pro
>> ject_id" = 1
>> => []
>> irb(main):005:0> part = p.participants.new(username:'toto')
>> => #<Participant id: nil, username: "toto", project_id: 1, created_at: nil,
>> updated_at: nil>
>> irb(main):006:0> p.participants
>> => [#<Participant id: nil, username: "toto", project_id: 1, created_at: nil,
>> updated_at: nil>]
>>
>> I always believed that the collection of participants should keep the same
>> size (zero in the above case) until I call save on the Project object. As
>> you see the collection has been changed by 1, despite the record has not
>> been yet save to the database; Is it a normal behaviour ?
>
> You have added one to the collection so it appears in the collection
> in memory. Note that there is no need to save the project object in
> order to add to its collection as nothing in the project object
> changes. It is the participant that must be saved at some point,
> otherwise it will be lost.

Thank you, Colin, for the answer, I believed that every time you call a collection method, for example:

project.participants

a DB query will be made to get it, but it is not the case.

Regards,


Serguei
>
> Colin
>
> --
> You received this message because you are subscribed to a topic in the Google Groups "Ruby on Rails: Talk" group.
> To unsubscribe from this topic, visit https://groups.google.com/d/topic/rubyonrails-talk/55RZkKBuYy0/unsubscribe?hl=en-US.
> To unsubscribe from this group and all its topics, send an email to rubyonrails-talk+unsubscribe@googlegroups.com.
> To post to this group, send email to rubyonrails-talk@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.
>
>

--
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.
For more options, visit https://groups.google.com/groups/opt_out.