Rails has_many复杂查询

Question

I'm not quite sure how to word this but I'll give it a shot.

Basically I have two models: Message and Event.

Message belongs_to event and event has_many messages.

When I call something like:

Event.first.messages

It produces this output:

SELECT "messages".* FROM "messages" WHERE "messages"."event_id" = 1

What I would like to be able to do is keep the association between the two, but add another column into the has_many equation so the SQL produced is something like:

SELECT "messages".* FROM "messages" WHERE "messages"."event_id" = 1 OR "messages"."type_id" = 4

Where both the Message and Event tables contain a type_id column.

Is this possible?

Answer 1

You can't make pure ActiveRecord OR queries

Other ways to solve this

Use SQL string as where argument:

Message.where("event_id = ? or type_id = ?", Event.first.id, 4)

Make 2 queries and then you add them:

event_messages = Event.first.messages
type_messages = Message.where(:type_id => 4)
all_messages = event_messages + type_messages

Raw SQL:

How to execute a raw update sql with dynamic binding in rails

Answer 2

Yes its possible By Using

Event.first.messages.where(:type_id => 4)

Try it

Answer 3

尝试这个

Event.first.find(:all, :conditions => ["where type_id = ? or event_id = ?", 4, 1])