MySQL FIELD function

[dvandersluis]

I created an extension for handling MySQL's FIELD function, would that be valuable as a PR? As far as I can tell, there's no parallel functions in the other RDBMSes (although it could maybe be faked with a CASE statement?), so I'm not sure if there's a way to handle non-universally supported functions, or a desire for them in this gem.

ids = [1, 2, 3, 4, 5]
Post.order(Post[:id].field(ids)).to_sql
=> "SELECT `posts`.* FROM `posts` ORDER BY FIELD(`posts`.`id`, 1, 2, 3, 4, 5)"

[jdelporte]

Hi Daniel,
If you can propose us an alternative for the different DBMSes, we will gladly accept such PR.
In the meantime, if you are sure to be using MySQL, you can use the node NamedFunction :

Arel::Nodes::NamedFunction.new('FIELD',[Post.arel_table[:id],1,2,3,4,5]).to_sql
=> "FIELD(`posts`.`id`, 1, 2, 3, 4, 5)"

[dvandersluis]

Yeah, I know about NamedFunction but I like to implement things we use frequently as extensions to arel-extensions because the syntax is much nicer IMO 😄

I'll try to figure out how I can implement FIELD for the other DBMSes.