Limit a text column in an ActiveRecord migration 5.0 using the PostgreSQL adapter

Question

I'm having a migration that looks like this

class CreateQuestionings < ActiveRecord::Migration[5.0]
  def change
    create_table :questionings do |t|
      t.text :body, null: false, limit: 260
    end
  end
end

Now when I run $ rake db:migrate:reset the limit is nowhere to be seen in my db/schema.rb:

create_table "questionings", force: :cascade do |t|
  t.text     "body",       null: false
end

Am I doing it wrong or is this a bug?

By the way, I am using rails 5.0.0.beta3 and ruby 2.3.0p0.

Answer 1

t.text produces a text column in PostgreSQL and text doesn't allow for size limits because text is:

variable unlimited length

Since there's no limit supported by the database, the PostgreSQL driver won't look for a :limit option; keep in mind that you're saying t.text(column_name, options_hash) so you can throw whatever you want into options_hash and the driver will ignore anything that it isn't specifically looking for.

If you want to limit the column size then you can either manually add a CHECK constraint (which ActiveRecord won't understand so you'll have to switch from schema.rb to structure.sql) or use a varchar column (AKA t.string):

t.string :body, null: false, limit: 260

Also, your schema.rb is generated based on what is in the database, not what's in your migrations. Since text doesn't support a limit, the database won't know about your limit: 260 option; if the database doesn't know about it, ActiveRecord won't get it back from the database when ActiveRecord is asking the database for schema information.