Question

I’m building a web application that needs a somewhat complex form to function.

I have five models: Grid, Row, Value, VariableGroup and Variable (these are not the actual names but useful for reference).

A Grid has many rows, and a Row has many values. Also, a Grid belongs to a VariableGroup, which is a sort of a model that groups many variables for their grandchildren.

A Variable, of course, belongs to a VariableGroup, and the key here, is that a Value belongs to a Variable as well.

The models:

class Grid < ActiveRecord::Base
  belongs_to :variable_group
  has_many :rows
  accepts_nested_attributes_for :rows, :allow_destroy => true
end

class Row < ActiveRecord::Base
  belongs_to :grid
  has_many :values
  accepts_nested_attributes_for :values, :allow_destroy => true
end

class Value < ActiveRecord::Base
  belongs_to :variable
  belongs_to :row
end

class Variable < ActiveRecord::Base
  belongs_to :variable_group
end

class VariableGroup < ActiveRecord::Base
  has_many :variables
  has_many :grids
end

---

The expected behavior is as follows to create a new Grid:

The user must select a VariableGroup from a dropdown select. This select has a jQuery handler for .change, that must instantiate a nested Row model, which in turn instantiates as many Value models as Variables exist in the Grid’s selected VariableGroup.

This is the grid form:

= simple_form_for @grid, :html => {:class => 'form-horizontal' } do |f|
    = f.input :name
    = f.association :variable_group_id
    .rows_and_values_container
      = f.simple_fields_for :rows do |p|
        = render 'rows_fields', :f => p
    = f.submit

And this is the attached listener:

$('document').ready(function(){
    $('#grid_variable_group_id').change(function(){
        $.ajax({url: '/grids/load_variables_in_values',
        data: 'selected=' + this.value,
        dataType: 'script'})        
    });
});

And this is the load_variables_in_values action:

def load_variables_in_values 
    @grid = Grid.new
    row = @grid.rows.build
    
    @variables = Variable.where(:variable_group_id => params["selected"])
    @variables.each do |variable|
        value = row.values.build
        value.variable_id = variable.id
    end
    # render :partial => "test_data_sets_fields"
    respond_to do |format|
      format.js
    end
end

The respond_to block yields the control to a js.erb view that should load the following partial, but I’m stuck here as I don’t know where and how to handle the loading of the partial and its sub-partials:

#rows_fields partial
= f.input :name
    = f.input :grid_id #Should be hidden
    = f.simple_fields_for :test_data_values do |p|
        = render 'values_fields', :f => p

#values_fields partial
= f.input :value
= f.input :row_id #Should be hidden
= f.input :variable_id #Auto-assigned

I think I’m 80% there, but I don’t know how to load the partials with its corresponding values with the data that I process in the custom controller action that was called via AJAX.

I know this is a mile long post, so thanks in advance if you got ºhere.

Answer 1

Rendering a partial from the custom controller action instead of using a respond_to block worked.

I just had to hard-code the scope of the form (reading the source of the auto generated form and using its structure as a string, together with a random value, and it worked.