Regarding form_for and fields-for content variable

Rails
1

I am trying to understand what I am working with when I deal with
Rails forms_for and fields_for constructors.

Given model has_many associations belongs_to dependency and
dependency has_many associations belongs_to model

@model = Model.find(:id)

and

forms_for @model do |f|

what is ‘f’?

f.fields_for :associations do |ff|

what is ‘ff’?

How do I access dependencies on the named associations?

I have inspected these things and the volume of data that each
contains is such that I cannot post it here. My difficulty is that I
cannot seem to get a handled

I will try to give an example:

forms_for @model do |f|

f.fields-for :associations do |ff|

ff.text-field :model_id
ff.text_field :dependency_id:

ff.dependency.some_attribute # this display value simply does not
work.

ff.collection_select(
:dependency_id, @dependencies, :id, :name,
{ :prompt => ‘Select a name’ }, #options hash
{ :class => :input_select, #html hash
:id => :input_name,
:size => 1,
:title => I18n.t(‘Enter a valid name’),
:value => ff.dependency_id } # this does not
work either
)

Now, while I know that ff != dependency it does seem to me counter
intuitive that for each association of model I am unable to directly
address the dependency attributes from within the form constructor.

What is my fundamental misunderstanding with respect to forms_for and
fields_for and their treatment of DBMS rows? How does one obtain a
dependent attribute for display purposes within a forms_for or
fields_for construct?

2

On Jan 26, 9:20 am, byrnejb [email protected] wrote:

Now, while I know that ff != dependency

This should be association rather than dependency. What I am asking
is why, when ff acts in the place of a specific model.association, I
cannot reach model.association.dependency.attribute.

The problem domain requires that associations be created separately
from either the model or the dependency but must be associated to an
extant qualified row in each.

3

James B. wrote:

I am trying to understand what I am working with when I deal with
Rails forms_for and fields_for constructors.

Given model has_many associations belongs_to dependency and
dependency has_many associations belongs_to model

@model = Model.find(:id)

and

forms_for @model do |f|

what is ‘f’?

A FormBuilder. The documentation for form_for already tells you this.

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

4

The most general it is a block value. For a from builder |f| is a
form object with association parameters that have attributes that
correspond to the object. f.text_field :name, :name is a db column
or an attribute of the class.

same as:
array.each do |val|
puts val
end