How can I set variables in Ruby with an if statement on one line?

Question

With Ruby, how can I set a variable based on a condition? Something like:

dog_name = params[:dog][:name] if params[:dog]

And then dog_name just wouldn't be set if params[:dog] wasn't set.

Right now I'm getting an error if params[:dog] is nil.

Answer 1

How about:

dog_name = params[:dog][:name] if params.has_key?(:dog) && params[:dog].has_key(:name)

What error are you getting when params[:dog] is nil?

Answer 2

You could use the && operator:

dog_name = params[:dog] && params[:dog][:name]

So now dog_name will be nil if params[:dog] does not exist, else it will be the value of params[:dog][:name].

Answer 3

You also could use the &&= operator:

dog_name = params.has_key(:dog)
dog_name &&= params[:dog].has_key(:name)
dog_name &&= params[:dog][:name]

Answer 4

How about:

dog_name = params[:dog][:name] unless params[:dog].nil?

Sujal

Answer 5

What you're doing should work.

I imagine that params[:dog] is not actually nil. I bet it's an empty string (or empty hash). (You can check on this by outputting params[:dog].inspect to the log or stdout.)

Rails has a method blank? that tests for nil, empty string, empty collection.

Try:

dog_name = params[:dog][:name] if !params[:dog].blank?

Or:

dog_name = params[:dog][:name] unless params[:dog].blank?