Ruby on Rails：“选择” MySQL命令

Question

I'm writing an application using MySQL. There's a table called "Requests".

That table has a field "user_id" from Table "Users".

I'd like to select all requests from a user_id .

For example:

SELECT * FROM requests WHERE user_id = ("the id I want");

How can I do that using Ruby language, and not an SQL string?

Answer 1

在ActiveRecords中，其操作如下：

Request.where(user_id: ID)

Answer 2

Request.find_by_user_id(USER-ID-YOU-WANT)

Or

Request.find_by user_id: 'USER-ID-YOU-WANT'

documentation here

Answer 3

There are a few different ways, as you can see from @shivam and @amalrik's answers. It also depends on the ORM you're using. If you're using Rails out of the box, you're probably using ActiveRecord .

Probably the most idiomatic way is to have the correct associations on your User and Request models.

in app/models/user.rb :

class User < ActiveRecord::Base
  has_many :requests
end

and app/models/request.rb :

class Request < ActiveRecord::Base
  belongs_to :user
end

This would allow you to find a user and call its #requests method:

User.find(user_id).requests