Rails has_many元数据

Question

我有一个模型声明多个has_many关系。在ActiveRelation中是否有元数据可供使用，以便我可以在使用此模型时循环访问这些has_many关系，以便查看该模型涉及多少个has_many关系，然后从中访问每个关系的内容？

一些伪代码（将无法运行），如果它有助于澄清我的目标是：

MyModel.has_many_relationships.each do |relationship| 
    relationship.contents.each do |content| 
     # ... 
    end 
end 

Answer 1

当然可以！

尝试在Rails文档中搜索“reflect_on_all_associations”！

reflect_on_all_associations(macro = nil) 

Returns an array of AssociationReflection objects for all the associations in the class. If you only want to reflect on a certain association type, pass in the symbol (:has_many, :has_one, :belongs_to) as the first parameter. 

Example: 

    Account.reflect_on_all_associations    # returns an array of all associations 
    Account.reflect_on_all_associations(:has_many) # returns an array of all has_many associations