ruby convert class name in string to actual class

Question

How do I call a class from a string containing that class name inside of it? (I guess I could do case/when but that seems ugly.)

The reason I ask is because I\'m us

Answer 1

"Object".constantize # => Object

Answer 2

I think what you want is constantize

That's an RoR construct. I don't know if there's one for ruby core

Answer 3

I know this is an old question but I just want to leave this note, it may be helpful for others.

In plain Ruby, Module.const_get can find nested constants. For instance, having the following structure:

module MyModule
  module MySubmodule
    class MyModel
    end
  end
end

You can use it as follows:

Module.const_get("MyModule::MySubmodule::MyModel")
MyModule.const_get("MySubmodule")
MyModule::MySubmodule.const_get("MyModel")

Answer 4

If you want to convert string to actuall class name to access model or any other class

str = "group class"

> str.camelize.constantize 'or'
> str.classify.constantize 'or'
> str.titleize.constantize

Example :
  def call_me(str)
    str.titleize.gsub(" ","").constantize.all
  end

Call method : call_me("group class")

Result:
  GroupClass Load (0.7ms) SELECT `group_classes`.* FROM `group_classes`

Answer 5

When ActiveSupport is available (e.g. in Rails): String#constantize or String#safe_constantize, that is "ClassName".constantize.

In pure Ruby: Module#const_get, typically Object.const_get("ClassName").

In recent rubies, both work with constants nested in modules, like in Object.const_get("Outer::Inner").

Answer 6

Given a string, first call classify to create a class name (still a string), then call constantize to try to find and return the class name constant (note that class names are constants).

some_string.classify.constantize