column: add support for Arel::Nodes::SqlLiteral

[kyrofa]

This PR resolves #252, allowing for more more advanced columns, such as extracting elements out of json arrays, or fields out of json objects. This is intended to be entirely backward compatible.

[chiperific]

Is this going to be released? I don't see this code in v.2.3.6

[egrueter-dev]

Can we get some proper documentation about how to use this?

[comictvn]

Can we get some proper documentation about how to use this?

me too

[diddeb]

➕ 1️⃣ on the docs. Or just a stupid-simple example for moots like myself.

[kalashnikovisme]

Found something useful in tests. An example, that works for me:

class Car < ApplicationRecord
  store_accessor :options, :number
end

class Driver < ApplicationRecord
  has_many :cars

  pg_search_scope(
    :pg_search,
    against: [:first_name, :last_name, :middle_name],
    associated_against: {
      cars: [Arel.sql("cars.options->>'number'")]
    },
    using: { tsearch: { prefix: true } }
  )
end

But looks like tsearch does not work for "cars.options->>'number'") column. Trying to fix it right now. It works well for first_name, etc. of Driver still.

As I know tsvector does not work with JSONB by default. As I see there is converting jsonb to string to be appropriate for tsvector, but it does not work.

[jakemcallister]

did you ever get this working?