Refactor and optimize query handling in Datagrid

- Simplified `append_column_queries` method in `active_record.rb` by using early return for empty columns and removing redundant code.
- Enhanced `apply` method in `base_filter.rb` to check for `dummy?` before proceeding with value application.
- Improved `apply` method in `date_filter.rb` to handle `dummy?` condition and format date as timestamp only when necessary.
- Updated test in `columns_spec.rb` to use grouped scope for better query testing.

Author: bogdan

lib/datagrid/drivers/active_record.rb

@@ -31,12 +31,10 @@ def to_scope(scope)
       end
 
       def append_column_queries(assets, columns)
-        if columns.present?
-          assets = assets.select(assets.klass.arel_table[Arel.star]) if assets.select_values.empty?
-          columns = columns.map { |c| "#{c.query} AS #{c.name}" }
-          assets = assets.select(*columns)
-        end
-        assets
+        return assets if columns.empty?
+        assets = assets.select(assets.klass.arel_table[Arel.star]) if assets.select_values.empty?
+        columns = columns.map { |c| "#{c.query} AS #{c.name}" }
+        assets.select(*columns)
       end
 
       def where(scope, attribute, value)

lib/datagrid/filters/base_filter.rb

@@ -35,7 +35,7 @@ def unapplicable_value?(value)
       end
 
       def apply(grid_object, scope, value)
-        return scope if unapplicable_value?(value)
+        return scope if dummy? || unapplicable_value?(value)
 
         result = execute(value, scope, grid_object)
 

lib/datagrid/filters/date_filter.rb

@@ -12,7 +12,9 @@ def default_input_options
       end
 
       def apply(grid_object, scope, value)
-        value = Datagrid::Utils.format_date_as_timestamp(value) if grid_object.driver.timestamp_column?(scope, name)
+        if !dummy? && grid_object.driver.timestamp_column?(scope, name)
+          value = Datagrid::Utils.format_date_as_timestamp(value)
+        end
         super
       end
 

spec/datagrid/columns_spec.rb

@@ -220,7 +220,7 @@ class Report27 < Datagrid::Base
 
   it "supports defining a query for a column" do
     report = test_grid do
-      scope { Entry }
+      scope { Entry.group("entries.id") }
       filter(:name)
       column(:id)
       column(:sum_group_id, "sum(group_id)")