让Rails的识别字符串

Question

我有一个存储类的名称的变量里面我的课

my_class = "Homework" 

这个类有一定的属性，我想访问

Homework.find_by 

我怎样才能让红宝石看到这个字符串作为一个对象？

例如

my_class.find_by 

Answer 1

您可以使用classify和constantize

my_class.classify.constantize.find_by # something 

classify

Create a class name from a plural table name like Rails does for table names to models. Note that this returns a string and not a Class (To convert to an actual class follow classify with constantize).

constantize

Tries to find a constant with the name specified in the argument string.

'Module'.constantize  # => Module 
'Test::Unit'.constantize # => Test::Unit 

如果你确定你的输入，你只需要constantize

my_class.constantize.find_by # something