Which is better?

gistfile1.rb

  t = Collection.arel_table
  where(t[:public].eq(true).or(t[:user_id].eq(user.id)))

# or

  where('public = ? OR user_id = ?', true, user.id)

For most cases I would strongly prefer the latter because it's significantly easier to read.

@duwanis I agree, but am curious if anyone has a good argument for the first

The more parameters you have for the query, the more the first form becomes preferable to the second because it's easier to tell which value should be mapped to which param.

If you're running a query that complicated, though, I'd say you need to be thinking about it differently anyway.

Good point. Another option if there are lots of parameters is to use the hash syntax:

where('public = :public OR user_id = :user_id', public: true, user_id: user.id)

True. I keep forgetting about that 😄

Also query builders for variable search parameters become super hairy with the second form. There's a reason arel won and it's because it scales to longer queries better.

@intjonathan thanks, that's a good point; building arbitrarily complex queries is pretty hairy with that second form unless it's just AND

Can you give an example of nice use of arel?

Not an issue in the simple case, but I believe that the second form will follow/respect/use aliasing of the table (as AR does sometimes with associations).