Rails - how can I use a variable for the model name in a controller?

Question

I need a def in my application_helper.rb that will accept the model name passed as a variable.

I have a nav view where i am trying to access a particular record based on the content of $current_opportunity

<%# link_to "Lab", lab_path(get_id('Lab')), class: get_labs_class() %>

What I was trying to do was call get_id and pass 'Lab' to it.

My application_helper.rb has

 def get_id(model)
    model_ids = model.where("opportunity_id = ? ", $current_opportunity)
    model_ids = model_ids.first
    model_id = model_ids.id
    model_id = model_id.to_i
    return model_id
  end

If I try to run like that, I get

NoMethodError in Prospects#show
Showing C:/Users/cmendla/RubymineProjects/product_development/app/views/shared/_tabs_nav.html.erb where line #61 raised:

undefined method `where' for "Lab":String
Trace of template inclusion: app/views/layouts/application.html.erb

Rails.root: C:/Users/cmendla/RubymineProjects/product_development

Application Trace | Framework Trace | Full Trace
app/helpers/application_helper.rb:25:in `get_id'
app/views/shared/_tabs_nav.html.erb:61:in `_app_views_shared__tabs_nav_html_erb__956794461_83328552'
app/views/layouts/application.html.erb:113:in `_app_views_layouts_application_html_erb___468328524_46368744'

However, if I change the def to

    model_ids = Lab.where("opportunity_id = ? ", $current_opportunity)

i.e hard wiring Lab, everything works.

Is there any way to substitute the value of model in the where statement?

alebian · Accepted Answer · 2016-10-12 17:02:47Z

1

Try:

model_ids = model.constantize.where("opportunity_id = ? ", $current_opportunity)

constantize also works with symbols

answered Oct 12, 2016 at 17:02

alebian

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