Fix ActiveRecord::StatementInvalid error when using UUID as primary key

[calvertyang]

If using UUID as primary key, the relationships feature raises ActiveRecord::StatementInvalid error when you try something like:

User.first.find_related_skills

ActiveRecord::StatementInvalid: PG::SyntaxError: ERROR:  syntax error at or near "a56f2e"
LINE 1: ...w FROM users, tags, taggings WHERE (users.id != 96a56f2e-393...
                                                             ^

[seuros]

This fixed uuid PK but broke integer/bigint

[calvertyang]

@seuros Thank you for pointing out my mistake.

How do you think if I use klass.columns_hash['id'].type to check the PK type first, and modify the method like this:

def exclude_self(klass, id)
  new_id = klass.columns_hash[klass.primary_key].type == :uuid ? "'#{id}'" : id if klass.primary_key

  "#{klass.table_name}.#{klass.primary_key} != #{new_id} AND" if [self.class.base_class, self.class].include? klass
end

[seuros]

I think we should use Arel in this part of code.

[calvertyang]

@seuros Thanks for your suggestion.
I'm not familiar with Arel, would you please confirm the following code is correct.

def exclude_self(klass, id)
  "#{klass.arel_table[klass.primary_key].not_eq(id).to_sql} AND" if [self.class.base_class, self.class].include? klass
end

[seuros]

Yes, i think it should work.
Can you rebase your PR ?

[seuros]

Also please include a test case.

[calvertyang]

@seuros Due to the definition of taggable_id in spec/internal/db/schema.rb is integer, the test case I wrote always failed.

And if I change the definition of taggable_id to uuid will make other test case broken, do you have any idea that how to modify my test case to make the CI build passed.

[seuros]

Thank you
We could generate uuid in postgresql and leave integer for mysql and sqlite3

[calvertyang]

Oh, I see. But I have no idea about how to modify the spec/internal/db/schema.rb that only generate uuid in postgresql and leave integer for mysql and sqlite3.

[seuros]

cherry-picked on #898 .