Rails 5 - in link_to, how to pass a nil (NULL) param?

Question

I have a link where I need to pass a sequence of params, where 2 params are always nill.

link_to go_to_action_path(id, par_01, par_02, par_03, par_04)

In some cases are the par_01 and par_02 nil, in other par_03 and par_04.

If I have these values in the variables:

par_01 = nil
par_02 = nil
par_03 = 'a'
par_04 = 'b'

And then in the go_to_action action:

p01 = params[:par_01]
p02 = params[:par_02]
p03 = params[:par_03]
p04 = params[:par_04]

I get these values:

p01 => a
p02 => b
p03 => 
p04 => 

In other words, the variables par_01 and par_02 will be thrown away and on their places will be moved in par_03 and par_04.

How can I force the link_to to accept a param with a nil value? I was thinking about placing there 0s instead of nils and then manually parse it in the controller action, but this is quite an ugly solution.

Answer 1

You can pass hash as the second option with id in your route

Use

link_to go_to_action_path(id, { par_01: par_01, par_02: par_02, par_03: par_03, par_04: par_04 })

Instead of

link_to go_to_action_path(id, par_01, par_02, par_03, par_04)

Then, In Controllers, say action name is action

# here you can use your params
def action
  p01 = params[:par_01]
  p02 = params[:par_02]
  p03 = params[:par_03]
  p04 = params[:par_04]
end