Rails core - Nov 2008 - About HTML attributes with the value 'false'

I''m puzzled by this latest commit:
"Tag helper should output an attribute with the value
''false'' instead of
omitting the attribute, if the associated option is false but not nil."
http://github.com/rails/rails/commit/4e9abdd7f1b4e05f8d1b50ddaa080b3ff63b92d9

What was the reason for this? How does it help in HTML? Thanks

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2008/11/14 <koziarski@gmail.com>
> f.hidden_field :some_boolean_attribute
>
> when the value is false, it gets turned into value = "", which
gets turned
> into nil by attributes=. Does it break something of yours?

So it''s about boolean fields and form serialization. Got it.

No, nothing broke for me, I was just wondering why output the attribute at
all. In HTML, foo="false" means that foo is true. Much more correct
for
attribute specified in Ruby as { :foo => false } is to produce no output at
all, and that we put some special-casing to form helpers like `hidden_field`
to convert booleans to strings prior to sending these attributes to common
tag helpers.

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On Nov 13, 11:55 pm, "Mislav Marohnić"
<mislav.maroh...@gmail.com>
wrote:
> I''m puzzled by this latest commit:
> "Tag helper should output an attribute with the value
''false'' instead of
> omitting the attribute, if the associated option is false but not
nil."http://github.com/rails/rails/commit/4e9abdd7f1b4e05f8d1b50ddaa080b3f...
>
> What was the reason for this? How does it help in HTML? Thanks
It''s because Rails 2.2 changed the way empty strings are mapped to
boolean model attributes.

Migration:
  create_table :people do |t|
    t.boolean :is_alien, :null => false
  end

Rails 2.1:
  p = Person.new(:is_alien => "")
  p.is_alien   # => false
  p.save       # => true

Rails 2.2:
  p = Person.new(:is_alien => "")
  p.is_alien   # => nil
  p.save       # => StatementInvalid: value for is_alien may not be
null in INSERT statement!


In my controller I have this:
  def new
    @person = Person.new
    @person.is_alien = false
  end

  def create
    @person = Person.new(params[:person])
    @person.save
  end

In the ''new'' view:
  <% form_for @person do |f| %>
    <%= f.hidden_field :is_alien %>

Before this commit, the hidden_field helper would output:
  <input type="hidden" name="person[is_alien]" />
As you can see, there''s no "value" attribute. Upon submitting
the
form, @person.is_alien would be set to nil instead of the expected
false, causing an SQL error. This is solved by making hidden_field
output value="false":
  <input type="hidden" name="person[is_alien]"
value="false" />
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2008/11/14 Hongli Lai <hongli@phusion.nl>
>
> Before this commit, the hidden_field helper would output:
>  <input type="hidden" name="person[is_alien]" />
> As you can see, there''s no "value" attribute. Upon
submitting the
> form, @person.is_alien would be set to nil instead of the expected
> false, causing an SQL error. This is solved by making hidden_field
> output value="false":
>  <input type="hidden" name="person[is_alien]"
value="false" />

Thanks Koz for a brief and Hongli for more detailed explanation, but I
don''t
think you got my question right.

You guys are talking about (hidden) textual form controls that map to
booleans. That''s fine. I''m talking about HTML attribute
serialization in
general, meaning *everything besides* textual form controls mapping to
booleans, and why I think this commit should be reverted. This is the
reason:

  <% tag :input, :type => "checkbox", :checked => false %>

Who here thought that this creates a text input that isn''t checked?
Well,
you thought wrong. This generates an initially checked box.

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>   <% tag :input, :type => "checkbox", :checked => false
%>
> Who here thought that this creates a text input that isn''t
checked? Well,
> you thought wrong. This generates an initially checked box.
OK, I now follow you.  A patch to fix this would be appreciated :)

-- 
Cheers

Koz

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On Nov 18, 8:27 pm, "Mislav Marohnić"
<mislav.maroh...@gmail.com>
wrote:
> Thanks Koz for a brief and Hongli for more detailed explanation, but I
don''t
> think you got my question right.
>
> You guys are talking about (hidden) textual form controls that map to
> booleans. That''s fine. I''m talking about HTML attribute
serialization in
> general, meaning *everything besides* textual form controls mapping to
> booleans, and why I think this commit should be reverted. This is the
> reason:
>
>   <% tag :input, :type => "checkbox", :checked => false
%>
>
> Who here thought that this creates a text input that isn''t
checked? Well,
> you thought wrong. This generates an initially checked box.
Good point. This has been fixed in
http://github.com/rails/rails/commit/0f89ed5636f69c7ae75f99ca2a613b1918de5f95

I''ve registered ''checked'' as a boolean HTML attribute
so that it
doesn''t get outputted when its value is false. If you encounter more
problems, then please suggest more attributes to register as boolean
HTML attributes.
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