Simple Rails question

I have a one-to-many association of Users<-Posts.

Some Posts are associated, others have a user_id of nil.

If, in ERB, I do:

post.user_id? po开发者_开发百科st.user.email

I get a

undefined method `email' for nil:NilClass

when iterating over Posts. Why does my initial conditional not protect against this?

---

I don't think your syntax makes sense. Try:

post.user.email if post.user_id?

or

post.user_id? ? post.user.email : nil

or

if post.user_id?
    post.user.email
end

or

post.user.try(:email)

All of those should work. Note: you should also be able to use post.user.present? or !post.user.nil? which both seem cleaner than checking the id.

---

You should be able to rephrase that slightly so that it makes more sense:

<%= post.user.email if post.user %>

I don't quite understand your code, as it doesn't look like a conditional from what you posted, but the above ERB statement should do the trick.

Edit: I should add that Ruby evaluates a nil object to false in a conditional statement, so there's no need to check for user.nil?, although that is still perfectly valid. That allows you to make short, simple conditional statements like the one above.