Rails - Apr 2006 - New to rails - scaffold command , how to get related items?

Ahoy,

I was able to follow the tutorials and build a simple to-do list program 
with Items and Categories and have the related tables link up w/ the 
default "scaffold :Items" command plus custom defenitions.

Then I erased all of that and tried rebuilding the program using the
ruby script/generate scaffold Item (and category) command.

Now the templates look like

"
  <% for column in Item.content_columns %>
    <td><%=h item.send(column.name) %></td>
  <% end %>
"

And putting

"
<td><%h item.Category ? item.Category.name : "no category"
%></td>
or
<td><% item.Category.name %></td>
"
both don''t work.

So, how exactly do I show related fields'' information now?
is there a slick way to do this automagically? Shouldn''t rails know
that
since there is a has_many and belongs_to in the model that these things 
may link up?

Will

-- 
Posted via http://www.ruby-forum.com/.

On Sat, 2006-04-15 at 23:57 +0200, Will Jessup wrote:
> Ahoy,
> 
> I was able to follow the tutorials and build a simple to-do list program 
> with Items and Categories and have the related tables link up w/ the 
> default "scaffold :Items" command plus custom defenitions.
> 
> Then I erased all of that and tried rebuilding the program using the
> ruby script/generate scaffold Item (and category) command.
> 
> Now the templates look like
> 
> "
>   <% for column in Item.content_columns %>
>     <td><%=h item.send(column.name) %></td>
>   <% end %>
> "
> 
> And putting
> 
> "
> <td><%h item.Category ? item.Category.name : "no
category" %></td>
----
try
<%=h item.Category ? item.Category.name : "no category" %>
----
> or
> <td><% item.Category.name %></td>
----
try
<%= item.Category.name %>
----
> "
> both don''t work.
> 
> So, how exactly do I show related fields'' information now?
> is there a slick way to do this automagically? Shouldn''t rails
know that
> since there is a has_many and belongs_to in the model that these things 
> may link up?
----
It does

Craig

On Sat, 2006-04-15 at 15:05 -0700, Craig White wrote:
> On Sat, 2006-04-15 at 23:57 +0200, Will Jessup wrote:
> > Ahoy,
> > 
> > I was able to follow the tutorials and build a simple to-do list
program
> > with Items and Categories and have the related tables link up w/ the 
> > default "scaffold :Items" command plus custom defenitions.
> > 
> > Then I erased all of that and tried rebuilding the program using the
> > ruby script/generate scaffold Item (and category) command.
> > 
> > Now the templates look like
> > 
> > "
> >   <% for column in Item.content_columns %>
> >     <td><%=h item.send(column.name) %></td>
> >   <% end %>
> > "
> > 
> > And putting
> > 
> > "
> > <td><%h item.Category ? item.Category.name : "no
category" %></td>
> ----
> try
> <%=h item.Category ? item.Category.name : "no category" %>
> ----
> > or
> > <td><% item.Category.name %></td>
> ----
> try
> <%= item.Category.name %>
> ----
> > "
> > both don''t work.
> > 
> > So, how exactly do I show related fields'' information now?
> > is there a slick way to do this automagically? Shouldn''t
rails know that
> > since there is a has_many and belongs_to in the model that these
things
> > may link up?
> ----
> It does
----
now that I''m looking at this, I don''t think Category the class
should be
used (capital "C")

if category belongs to item, then you should only need to use...

<%= item.category.name %>

Craig

On Apr 15, 2006, at 3:34 PM, Craig White wrote:
> now that I''m looking at this, I don''t think Category the
class
> should be
> used (capital "C")
>
> if category belongs to item, then you should only need to use...
>
> <%= item.category.name %>
If item has_many categories, then you need:

   item.categories

but you cannot say:

   item.categories.name

because categories is plural, and therefore will return an array of
categories, even if there''s only one.

So, you might want to try:

   item.categories.collect { |c| c.name }.join('', '')

This code iterates through the array returned by item.categories,
an returns a new array of names which is then iterated over again
by join, which contatenates them with comma-space between each
pair.

-- 
-- Tom Mornini

Craig- thanks, all I needed was the "=" (omfg).

Tom, yea that''s not the problem.


I was thinking, though - if you put has_many: and belongs_to, shouldn''t
the auto-scaffold know to connect those things automagically (including 
creating select boxes) in the list/edit/new ? or is that too much 
automation?

2nd -
<%= item.category.name %>

I had the "C" capitalized because that''s how it is in the
model, i''m not
sure what the standard is. Also, has_many is plural and belongs_to is 
singular. this is normal right? as in- not every association in the 
model is either singular/plural, but depending on context (that''s what 
i''m doing now, just double checking)

Will

THanks much!



Tom Mornini wrote:
> On Apr 15, 2006, at 3:34 PM, Craig White wrote:
> 
>> now that I''m looking at this, I don''t think Category
the class
>> should be
>> used (capital "C")
>>
>> if category belongs to item, then you should only need to use...
>>
>> <%= item.category.name %>
> 
> If item has_many categories, then you need:
> 
>    item.categories
> 
> but you cannot say:
> 
>    item.categories.name
> 
> because categories is plural, and therefore will return an array of
> categories, even if there''s only one.
> 
> So, you might want to try:
> 
>    item.categories.collect { |c| c.name }.join('', '')
> 
> This code iterates through the array returned by item.categories,
> an returns a new array of names which is then iterated over again
> by join, which contatenates them with comma-space between each
> pair.
> 
> --
> -- Tom Mornini

-- 
Posted via http://www.ruby-forum.com/.

Oh, as a future note - One of my category_id fields in the categories 
table was blank, this caused an error as well.

-- 
Posted via http://www.ruby-forum.com/.

On Sun, 2006-04-16 at 04:15 +0200, Will Jessup wrote:
> Craig- thanks, all I needed was the "=" (omfg).
> 
> Tom, yea that''s not the problem.
> 
> 
> I was thinking, though - if you put has_many: and belongs_to,
shouldn''t
> the auto-scaffold know to connect those things automagically (including 
> creating select boxes) in the list/edit/new ? or is that too much 
> automation?
> 
> 2nd -
> <%= item.category.name %>
> 
> I had the "C" capitalized because that''s how it is in
the model, i''m not
> sure what the standard is. Also, has_many is plural and belongs_to is 
> singular. this is normal right? as in- not every association in the 
> model is either singular/plural, but depending on context (that''s
what
> i''m doing now, just double checking)
> 
----
I think it''s a ruby thing - you might want to pick up a copy of the
''PickAxe'' book aka "Programming Ruby" by Dave Thomas

anyway, I think the early version is online and you can read about
variables/classes etc. here...

http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_classes.html

Craig

On Sun, 2006-04-16 at 04:15 +0200, Will Jessup wrote:
> Craig- thanks, all I needed was the "=" (omfg).
> 
> Tom, yea that''s not the problem.
> 
> 
> I was thinking, though - if you put has_many: and belongs_to,
shouldn''t
> the auto-scaffold know to connect those things automagically (including 
> creating select boxes) in the list/edit/new ? or is that too much 
> automation?
> 
> 2nd -
> <%= item.category.name %>
> 
> I had the "C" capitalized because that''s how it is in
the model, i''m not
> sure what the standard is. Also, has_many is plural and belongs_to is 
> singular. this is normal right? as in- not every association in the 
> model is either singular/plural, but depending on context (that''s
what
> i''m doing now, just double checking)
----
I neglected to comment on singular/plural.

It is the natural context that defines the ''defaults''.

has_many :plural
has_one  :singular

Class & model refer to a single record. 

Craig