newbie stumped - when form validates, normally return is fine, but when I select a certain checkbox, I end up with a new object created on return

I'm really stumped here. I'm new to Rails and I'm sure I'm doing something stupid but what's going on seems like voodoo or something. When you click on "new match" the controller makes a call to set up two new objects to be populated. You're brought to your form (see figure 1). When you submit a form with improper validation, typically things work fine - validation errors show up and you are returned to the form with the two objects populated with what you had, and the errors display (see figure 2.)

The part that has me so stumped is that when you happen to check the "home" checkbox and you submit, I end up with an extra object created when validation fails! (see figure 3, you'll see the extra player game object column.) I have no idea why, and I have no idea why selecting this checkbox causes it to happen? Why does only this form field cause the problem and not the other form fields???

figure 1: Skitch | Evernote figure 2: Skitch | Evernote figure 3: Skitch | Evernote

Can someone give me some tips as to what even might be wrong or where I should start to look? I have some log statements and the same flow seems to happen regardless of the scenario.

I posted the main controller and a few other things that I think might be relevant here http://pastie.org/335194 in case anyway wants to help by taking a look.

The log doesn't show much that seems to help me. Here is the log http://pastie.org/335259 after the "create" button is hit and the form submits. Notice at the end you'll see "3" calls to something like:

Compiling template _run_erb_47app47views47matches47_player_game46html46erb_locals_g_object_player_game   [4;36;1mCACHE (0.0ms)[0m [0;1mSELECT * FROM "players" ORDER BY first_name ASC[0m   [4;35;1mCACHE (0.0ms)[0m [0mSELECT * FROM "teams" ORDER BY name ASC[0m

When I think you should only see "2." (and actually you will only see '2' if you don't select the 'home' checkbox.) Any time you submit the form and the checkbox ("home") is selected this happens. If I don't select 'just' that checkbox things work fine.

[ORIGINAL POST:]

I'm really stumped here. I'm new to Rails and I'm sure I'm doing something stupid but what's going on seems like voodoo or something. When you click on "new match" the controller makes a call to set up two new objects to be populated. You're brought to your form (see figure 1). When you submit a form with improper validation, typically things work fine - validation errors show up and you are returned to the form with the two objects populated with what you had, and the errors display (see figure 2.)

The part that has me so stumped is that when you happen to check the "home" checkbox and you submit, I end up with an extra object created when validation fails! (see figure 3, you'll see the extra player game object column.) I have no idea why, and I have no idea why selecting this checkbox causes it to happen? Why does only this form field cause the problem and not the other form fields???

figure 1: Skitch | Evernote figure 2: Skitch | Evernote figure 3: Skitch | Evernote

Can someone give me some tips as to what even might be wrong or where I should start to look? I have some log statements and the same flow seems to happen regardless of the scenario.

I posted the main controller and a few other things that I think might be relevant here http://pastie.org/335194 in case anyway wants to help by taking a look.

On Tue, Dec 9, 2008 at 3:22 PM, Shandy Nantz

Can someone give me some tips as to what even might be wrong or where I should start to look? I have some log statements and the same flow seems to happen regardless of the scenario.

Is this rails check box trickery tripping you up ? The rails check box helper creates a hidden input field with the same name (and value 0) as well as the actual check box. If you're using arrays of parameters like I think you are this can mess things up. If so then one work around is to use check_box_tag instead of check_box (but which has the downside of when the box is not ticked you won't get any param for it rather than receiving a '0'. The other way out is to make your params a hash keyed by indices rather than an array (I mention this at the bottom of Parametrised to the max - Space Vatican )

Fred

Thanks Fred, I will look into this tonight and try some of these suggestions out.

How it ends up interfering to the point that a "new nested object" is created other than the two I originally started with though, seems really weird.

I look forward to seeing if your suggestions fix things.

In what ways does it mess things up? (I know things get screwy as I posted in my original post, yet have no idea WHY the before I'm seeing is happening, where a new object ends up being created.) I posted some of the raw html here http://pastie.org/335814

but as a summary, yes the checbox field is part of an array and looks like;

<input id="match_new_game_attributes__home" name="match[new_game_attributes][home]" type="checkbox" value="1" /><input name="match[new_game_attributes][home]" type="hidden" value="0" /> Yes

<input id="match_new_game_attributes__score" name="match[new_game_attributes][score]" size="30" type="text" />

Even when validation fails the form returns correctly with the checkbox checked that I selected and everything looks fine, except an entire stinkin' new match[new_game_attributes] object was created!! It's driving me nuts. Why would a checkbox cause this behavior?

I'll pay someone 15 bucks (I'd pay more, but hey, the economy:) if they can help me figure it out just so I can learn. I put the little app here

http://dl-client.getdropbox.com/u/86998/hockey.zip

just uses built in sql-lite http://localhost:3000/matches select new match, (uesrname: admin password: wombat) and then check one of the 'home' checkboxes and notice you'll end up with an extra instance of a player game on the form when validation fails. If you DO NOT check that checkbox the extra instance is not created when validation fails.

Is this rails check box trickery tripping you up ? The rails check
box helper creates a hidden input field with the same name (and value 0) as well as the actual check box. If you're using arrays of parameters like I think you are this can mess things up.

In what ways does it mess things up? (I know things get screwy as I posted in my original post, yet have no idea WHY the before I'm seeing is happening, where a new object ends up being created.) I posted some of the raw html here http://pastie.org/335814

It all comes down to how array parameters are handled. If the
parameters you get look like match[new_game_attributes][foo]=bar match[new_game_attributes][bar]=baz

then you get params == {:match => {:new_game_attributes => [{:foo =>
'bar', :bar => 'baz'}]}}

if you had

match[new_game_attributes][foo]=bar match[new_game_attributes][bar]=baz

match[new_game_attributes][foo]=alice match[new_game_attributes][bar]=bob

then you'd expect params == {:match => {:new_game_attributes => [{:foo
=> 'bar', :bar => 'baz'}, {:foo => 'alice', :bar => 'bob}]}}

The key thing here to note is that it is the repetition of a parameter
that causes rails to add a new array element. so if your checkbox is
checked and your parameters look like

match[new_game_attributes][name]=fred match[new_game_attributes][home]=0 match[new_game_attributes][home]=1

then you'll get parameters like {:match => {:new_game_attributes =>
[{:name => 'fred', :home => '0'}, {:home => '1'}]}} ie two array elements where you only wanted one, which (as I
understood it) was the problem you were grappling with

Fred