The agile book says “You can inspect variables, set values, add other
breakpoints, and generally have a good time”.
This is very sweet and totally useless. For example, I want to see the
session variable,
the cookies variable and so on. These names are unknown. I think I
guess that the things
that are available depend on where you put the breakpoint() call. I’ve
tried a couple of
different spots and “session” is unknown.
For example in the Depot example I have “class AdminController <
ApplicationController”.
But I don’t know the name of the AdminController object so I can’t find
AdminController.session. Likewise for the other ApplicationController.
Likewise I have
models derived from ActiveRecord::Base. I can call find() because
that’s class method.
But what about the instance variables of my AR objects?
script/console is not useless, but its not an end all tool either. The
console does indeed have the limitation that its pretty dumb when it
comes to your actual controllers/views in that it doesn’t handle them
at all. It does however give you full access to all your models and
database interaction, as well as all the other rails and ruby goodness
on the command line.
You can do anything in the console that you can do in Ruby (ie, you
can set variables, define new methods/classes, overwrite classes,
whatever, its just ruby)
This is very sweet and totally useless. For example, I want to see the
session variable, the cookies variable and so on. These names are
Man…console is one of the most cool and innovative tools in rails…
Its really helpful to get into your app using console, inspect objects,
call methods etc…
If you have a production site and it keeps crashing, it very helpful
load the app in console, try to rerun the things that crashed the app,
inspect the involved objects, etc…
I wish i could do that in my day job…(java)…
Mikkel B.
www.strongside.dk - Football Portal(DK) nflfeed.helenius.org - Football News(DK)
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So how do I use it to inspect objects and call methods? For example,
what is the name of
the objects that are of class ApplicationController? Where is the list
of class methods I
can use as accessors? If I start console or breakpointer and type:
…> p session
I get nothing useful. Likewise for
…> session.inspect
Maybe if the API documentation had a decent search feature it would be
okay but it
doesn’t. I often use it offline from the internet and so I can’t even
use google.
I can see that console and breakpointer are different. What I cannot
see is a list of
their differences and capabilities. Nor do I have enough information to
figure it out on
my own. Yes, I can call model.find(). But heck, I can enter sql
directly into the
database utilities to grab that information.
“Man…console is one of the most cool and innovative tools in
rails…”
Basically, I have come to doubt this. Console doesn’t show
anything. There is no useful
help facility. You have to guess the names of things to display,
and methods to call. IRB
works great for source I’ve written. Do I have to study the rails
source to use console?
A couple of days ago I added auxiliar columns for sorting in some
tables. Those columns are maintained with callbacks, but the already
existing records had them set to null. Right, I just fired up the
console and wrote
Employee.find(:all).each { |e| e.save }
and voila!
You could do that with a script, but the point is that you have the
entire environment up right at the tip of your fingers. That is handy
for some tasks.
Sometimes I also prefer to inspect the database through models than
through a database browser.
Based on the responses from Mikkel and Xavier, console is for models
only.
Let’s say I have two users logged in and I want to inspect their session
variables. Let’s
say it’s in development and I’m really both users. How do I get to the
rails data that
describes the sessions and the cookies and the stuff that indicates
where each individual
logged in user is in the website?
Do I use the debugger or the console? Mikkel says “find some object”.
Right now that’s
the hard part for me. I can find database entries. It’s rails stuff I
haven’t found.
“Man…console is one of the most cool and innovative tools in rails…”
Basically, I have come to doubt this. Console doesn’t show anything.
There is no useful
help facility. You have to guess the names of things to display, and
methods to call. IRB
works great for source I’ve written. Do I have to study the rails
source to use console?
Or does one write reflection scripts to search the object space? That
hardly seems like a
way to debug. I’ve debugged hex dumps of running C programs, I’ve
debugged embedded
systems with in-circuit emulators, and I’ve used several debugging
IDE’s. But whatever
the debugging paradigm is in Rails, it’s none of those.
You set a breakpoint in your application for example at the beginning
of an action in your controller. you run the breakpointer script. you
navigate to the url of your action with one of your users, once the
breakpoint is hit, you get an interactive prompt in the window where
you ran breakpointer, in which you can access whatever variables,
objects, methods,… are in the scope of the action.
On Wednesday, February 22, 2006, at 2:50 PM, Warren S. wrote:
Do I use the debugger or the console? Mikkel says “find some
object”. Right now that’s
the hard part for me. I can find database entries. It’s rails
stuff I haven’t found.
console is for models only (which should contain approx 90% of your
logic)…
what you seem to need is the breakpointer…
breakpointer will hook up to a running proces. Stop it, and let you
inspect it…so its only good for development…
console can be use like ‘irb’ for rails…
Mikkel B.
www.strongside.dk - Football Portal(DK) nflfeed.helenius.org - Football News(DK)
ting.minline.dk - Buy Old Stuff!(DK)
On Wed, 22 Feb 2006 14:26:18 +0200, Warren S. wrote:
That hardly seems like a
way to debug. I’ve debugged hex dumps of running C programs, I’ve debugged embedded
systems with in-circuit emulators, and I’ve used several debugging IDE’s. But whatever
the debugging paradigm is in Rails, it’s none of those.
I think you debug like I debug… and I don’t think Rails debugs like
that.
The paradigm, at least at the moment, is (a) print statements, and (b)
pre-planned breakpoints.
The good news is that, because Ruby’s interpreted, sticking a print
statement into a page and reloading is not really any more work than
setting a breakpoint with an auto-display condition. But it just FEELS
wrong. And, with no core dumps, memory step-throughs, etc., there’s no
way
to debug a crash post-crash, which makes troubleshooting intermittent,
non-deterministic problems difficult.
If you look at debug.rb, you’ll see it’s pretty easy to extend, but
step-by-step debugging in pure Ruby is just painfully slow. There’s a
C-based Ruby debugger (ArachnoRuby, I think), but last I heard it can’t
run
a Rails app.
I’ll be curious to see how all this changes as both Rails and Ruby
mature,
especially with YARV.
That hardly seems like a
way to debug. I’ve debugged hex dumps of running C programs, I’ve
debugged embedded
systems with in-circuit emulators, and I’ve used several debugging IDE’s.
But whatever
the debugging paradigm is in Rails, it’s none of those.
Yeah Rails is not targetted at embedded systems. Maybe you could write
a
plugin?
I don’t think you can use script/console for the session var because
that runs separately
from the regular http request cycle. It just reads in your app’s
environment so that you
can create models and make db calls.
I think what you want is the breakpointer. Put a “breakpoint” in a
controller or in a <%%>
in a view, start script/breakpointer in a terminal, use a browser to run
a request and the
breakpointer will hook up to that breakpoint in the code with all the
current state of the
http request… including the session… I’ve done is that way anyway.
Oh and your original request was to look at two different sessions…
just run the same
request through two different browsers logged in as the two different
users.
Based on the responses from Mikkel and Xavier, console is for models
only.
Console is a parallel layer on top of the models. It’s an alternative
to HTTP/FCGI/Controller. It is not a management console with which to
view a running app instance.
