ActiveRecord的方法不暗示数据库或转换为哈希/数组

Question

I have a model foo and in my index action I do:

@foos = foo.all 

and now, on the view I want to know if this @foos contain a record whit foo.id = whatever

One method of do that is @foos.exists?(id: whatever) , but this method implies a bd query and I want avoid this.

Other method will be @foos.collect(&:id).include?(whatever) but this implies the conversion of all @foos into array, another case that I would avoid.

There are another ways to accomplish it?

Thanks in advance

UPDATE

I want also get this object not only know if exists, sorry for bad explanation.

Answer 1

You can use the Enumerable#any? to check if the value exists in the array of results:

@foos.any? { |foo| foo.id == whatever }

This check will be performed on the result array without hitting the database again and without converting the array to another structure.

UPDATE

If you want the object returned, use Enumerable#find , like this:

@foos.find { |foo| foo.id == whatever }

This will return the first occurrence where foo.id == whatever .