Rails core - Jan 2006 - Re: [Rails] Can Rails render pages if there is no database connected?

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On Jan 1, 2006, at 4:00 PM, Duane Johnson wrote:

>> I thought I knew the answer to this question (''yes''),
however,
>> recently I''ve been trying to build an app that detects whether
or
>> not the administrator has correctly configured the database. 
I''d
>> like to give instructions in the negative case.
>>
>> So here''s where I''m at: if the database is
configured, my app runs
>> wonderfully; however, if the database doesn''t exist, or if the
>> database login/password is incorrect, then Rails is completely  
>> unresponsive.  When I load any page, I get a blank white screen.   
>> Checking the logs (even the server output) gives nothing at all  
>> (not even a GET is reported in the terminal where I have Lighttpd  
>> running).
>>
>> I created a simple Rails application from scratch ("rails
simple"
>> at the command line) and went to the index.html page.  That worked  
>> fine; however, the ''About your application''s
environment'' link
>> shows nothing but a thin yellow line.  Checking the URL that it  
>> goes to confirms that the same thing as described above is  
>> occurring: no response at all.
>>
>> Is this expected behavior, or is there something obvious I''m
doing
>> wrong that''s preventing my app from running without the
database?
>>
>> Thanks,
>>
>> Duane Johnson
>> (canadaduane)
>> http://blog.inquirylabs.com/
>>
>>
>>
>>
>
> Duane-
>
> 	I have seen the exact same behavior for a few reasons. I get the  
> blank screen in a fresh rails app just like you describe when the  
> database isn''t connected or database.yml is not filled out. I also
> get it if I do something in environment.rb that doesn''t work like
> require a file that can''t be found. It seems like it rails kind of
> gets hung trying to load its environment so no errors go to any  
> logs and you just get a white screen with no errors anywhere. The  
> same thing can happen sometimes when you have stale old sessions  
> in /tmp.
>
> 	I hate the empty screen, rails should have kittens when this  
> happens and put errors in the logs or something. It can be a  
> frustrating problem to debug as well.
>
> 	Anyway, I''m just confirming this behavior as I see the same thing
> you do.
>
>
> Cheers-
> -Ezra Zygmuntowicz
Is this happening for a reason?  It seems to me that Rails should be  
a little more robust on its "minimum requirements" for a basic  
controller and view to work properly.  I''d like to investigate  
further, so I''m looking for a little feedback first.

Duane Johnson
(canadaduane)
http://blog.inquirylabs.com/

> Is this happening for a reason?  It seems to me that Rails should be
> a little more robust on its "minimum requirements" for a basic
> controller and view to work properly.  I''d like to investigate
> further, so I''m looking for a little feedback first.
>
> Duane Johnson
> (canadaduane)
> http://blog.inquirylabs.com/
There are several error conditions where rails does that ''blank
screen'' stuff.   I try to fix them as I hit them.    I can''t
see a
valid reason for this behaviour, so perhaps investigate a patch for
it?


--
Cheers

Koz

On Jan 2, 2006, at 3:12 PM, Michael Koziarski wrote:
>> Is this happening for a reason?  It seems to me that Rails should be
>> a little more robust on its "minimum requirements" for a
basic
>> controller and view to work properly.  I''d like to investigate
>> further, so I''m looking for a little feedback first.
>>
>> Duane Johnson
>> (canadaduane)
>> http://blog.inquirylabs.com/
>
> There are several error conditions where rails does that ''blank
> screen'' stuff.   I try to fix them as I hit them.    I
can''t see a
> valid reason for this behaviour, so perhaps investigate a patch for
> it?
>
I''m not sure how to fix the blank screen I was getting due to having  
no DB connection; however, to fix the session restore blank screen  
mentioned by Ezra Z. line 102 of cgi_process.rb is the culprit in  
that case:

               @session = CGI::Session.new(@cgi,  
session_options_with_string_keys)

When switching apps (usu. on a development machine where this is  
common) the session restore coughs and dies without a trace because  
models are not the same.  I think this has been discovered several  
times in a variety of ways (at least, I remember seeing some tickets  
on this).

In the CGI::Session rdocs it says, "If your application switches from  
one to the other without making sure that filenames will be different  
and clients still have old sessions lying around in cookies, then  
things will break nastily!"

So I''m wondering if we need to have a unique "application id"
that
gets stored in the session.  If such a thing existed, we could then  
test to make sure the session''s APP ID matches the current APP ID.   
Otherwise, bust an exception.

I think the best place to put the unique APP ID would be in the  
railties code so a UUID is created whenever a new rails app is  
generated.

Anyone have a better alternative?

Duane Johnson
(canadaduane)
http://blog.inquirylabs.com/




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"Rails should be robust on its "minimum requirements" for a basic
controller
and view to work properly." 

This was January, it is June. Is there a patch? Can Rails work without a
database connected?

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On 23/06/2006, at 7:34 AM, anne001 wrote:
> "Rails should be robust on its "minimum requirements" for a
basic
> controller
> and view to work properly."
>
> This was January, it is June. Is there a patch? Can Rails work  
> without a
> database connected?
Umm... have you tried yourself?

$ rails test_site
$ cd test_site
$ ./script/generate controller test index
$ rm public/index.html
$ ./script/server

then browse to http://127.0.0.1:3000/test and voilà!
> Test#index
>
> Find me in app/views/test/index.rhtml
-- tim

Thanks I will try it. 

I tried to follow this recipee
http://media.pragprog.com/titles/fr_rr/NoDatabase.pdf
and I got mysql errors with 
ruby test/functional/my_controller_controller_test.rb
Trying to follow that tutorial gave me the idea that rails really mean
rails, you have to want to go from station to station. 




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On 23/06/2006, at 9:42 AM, anne001 wrote:
> Thanks I will try it.
>
> I tried to follow this recipee
> http://media.pragprog.com/titles/fr_rr/NoDatabase.pdf
> and I got mysql errors with
> ruby test/functional/my_controller_controller_test.rb
> Trying to follow that tutorial gave me the idea that rails really mean
> rails, you have to want to go from station to station.
Ah yeah, unit tests are a different kettle of fish. It might be handy  
to make a patch that makes those DB rake tasks check  
included_frameworks for ActiveRecord.

-- tim

Don't forget that you can tell Rails not to require certain frameworks (in
this case ActiveRecord)
in your environment configuration (environment.rb). The line that shows how
to do that is commented with
active_mailer and action_web_service as an example; just add active_record
to the array.

On 6/23/06, Tim Lucas <t.lucas@toolmantim.com>
wrote:
>
> Umm... have you tried yourself?
>
> $ rails test_site
> $ cd test_site
> $ ./script/generate controller test index
> $ rm public/index.html
> $ ./script/server
>
> then browse to http://127.0.0.1:3000/test and voilà!

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