Similar to the work done in #38636, instead of using case statements we
can make these classes respond to `fetch_attribute`.
New classes can implement `fetch_attribute` instead of adding to the
case statement, it's more object oriented, and nicer looking.
Co-authored-by: Aaron Patterson <aaron.patterson@gmail.com>
module.
Reason for doing this change is to pull the node specific changes to
module itself and to not infer on the attributes, rather than assign
responsibility to the member functions to do so.
Current code expect an `eq` node has one arel attribute at least, but an
`eq` node may have no arel attribute (e.g. `Arel.sql("...").eq(...)`).
In that case `unscope` will raise `NoMethodError`:
```
% bundle exec ruby -w -Itest test/cases/relations_test.rb -n test_unscope_with_arel_sql
Using sqlite3
Run options: -n test_unscope_with_arel_sql --seed 4477
# Running:
E
Error:
RelationTest#test_unscope_with_arel_sql:
NoMethodError: undefined method `name' for #<Arel::Nodes::Quoted:0x00007f9938e55960>
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/where_clause.rb:157:in `block (2 levels) in except_predicates'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/arel.rb:57:in `fetch_attribute'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/where_clause.rb:157:in `block in except_predicates'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/where_clause.rb:156:in `reject'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/where_clause.rb:156:in `except_predicates'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/where_clause.rb:31:in `except'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/query_methods.rb:487:in `block (2 levels) in unscope!'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/query_methods.rb:481:in `each'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/query_methods.rb:481:in `block in unscope!'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/query_methods.rb:471:in `each'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/query_methods.rb:471:in `unscope!'
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/relation/query_methods.rb:464:in `unscope'
test/cases/relations_test.rb:2062:in `test_unscope_with_arel_sql'
```
We should check for both `value.left` and `value.right` those are arel
attribute or not.
This fixes a bug that the `foreign_key` and the `foreign_type` are
separated as different table conditions if a polymorphic association has
a scope that joins another tables.
