Default :date in Migration

the exception message is actually pretty good.. you need to use a fragment - see docs for solution

https://hexdocs.pm/ecto/Ecto.Migration.html#fragment/1

Ok, can you explain whats a fragment and how to use it?

create table(:posts) do
  add :inserted_at, :naive_datetime, default: fragment("now()")
end

the fragment() function is calling a now() function?

I believe a fragment is best described as ‘custom sql’

the now() function is a function in postgres PostgreSQL: Documentation: 9.6: Date/Time Functions and Operators

modify :data, :date, [null: false, default: fragment("now()")]

should work, although you are using a date field, so I’m not 100% - you might need to use:
modify :data, :date, [null: false, default: fragment("current_date")]

Thank you very much! =)