Question

So I have a join table that relates to multiple models and stores the appropriate id and class like so:

Statistics
-----------------------------------
|object_type | object_id | value  |
-----------------------------------
| "User"     |     1     |  100   |
-----------------------------------
| "Post"     |     61    |  50    |
-----------------------------------

I was hoping to use metaprogramming to do pass the “object_type” and somehow and use the resulting object like so:

send("User").find(1)        #i.e. User.find(1)
send("Post").find(61)       #     Post.find(61)

Is there any good way to do this short of constructing a complicated if-else or case statement (i.e. if object_type == “User”…) ???

Answer 1

Classes are named with constants, so you can turn strings into classes easily with const_get:

self.class.const_get("User").find(1)

or

Object.const_get("User").find(1)

But it’s generally better to use the first version as it’s closer to what you get when you refer to the class directly.