Question

i have some code that uses a string to determine dynamically what model class to use and for what field to find_by() on. however, i’m having a hard time with how to use these variables to get the model instance. specifically, i have

class Item
  include MongoMapper::Document
  key :my_variable, String

in my code i have

m = "Item"
f = "my_variable"

and i want to be able to

i = m.find_by_my_variable( f )
result = i[f]

any help is appreciated!

Answer 1

Since you’re in Rails (judging by the category tag) you can use:

m = m.constantize

to make the string a constant, and then would something like this work for your query?

m.where("#{f} = ?", some_value)

(EDIT) or use send as ismaelga suggested, if you don’t want an ActiveRecord::Relation array object