fix summing custom fields on wp table

Before the fix, string values where returned and then the `+` method was called which lead to the strings being concatenated. A subsequent call of `integer?` failed. The fix performs the aggregation in the database which is not only correct then but can also be carried out considerably faster. The drawback is, that the casting breaks the abstraction introduced by the cf strategies

app/models/queries/work_packages/columns/custom_field_column.rb

@@ -75,16 +75,19 @@ class Queries::WorkPackages::Columns::CustomFieldColumn < Queries::WorkPackages:
 
   def sum_of(work_packages)
     if work_packages.respond_to?(:joins)
-      # we can't perform the aggregation on the SQL side. Try to filter useless rows to reduce work.
-      work_packages = work_packages
-                      .joins(:custom_values)
-                      .where(custom_values: { custom_field: @cf })
-                      .where("#{CustomValue.table_name}.value IS NOT NULL")
-                      .where("#{CustomValue.table_name}.value != ''")
-    end
+      cast = @cf.field_format == 'int' ? 'INTEGER' : 'FLOAT'
 
-    # TODO: eliminate calls of this method with an Array and drop the :compact call below
-    work_packages.map { |wp| value(wp) }.compact.reduce(:+)
+      CustomValue
+        .where(customized: work_packages, custom_field: @cf)
+        .where.not(value: nil)
+        .where.not(value: '')
+        .pluck("SUM(value::#{cast})")
+        .first
+    else
+      # TODO: eliminate calls of this method with an Array and drop the :compact call below
+      ActiveSupport::Deprecation.warn('Passing an array of work packages is deprecated. Pass an AR-relation instead.')
+      work_packages.map { |wp| value(wp) }.compact.reduce(:+)
+    end
   end
 
   def self.instances(context = nil)

app/models/query/sums.rb

@@ -100,7 +100,8 @@ module ::Query::Sums
 
   def crunch(num)
     return num if num.nil? or num.integer?
-    Float(format '%.2f', num.to_f)
+
+    Float(format('%.2f', num.to_f))
   end
 
   def group_for_issue(issue = @current_issue)
@@ -121,7 +122,7 @@ module ::Query::Sums
 
   def all_total_sums
     query.available_columns.select { |column|
-      column.summable? && Setting.work_package_list_summable_columns.include?(column.name.to_s)
+      should_be_summed_up?(column)
     }.inject({}) { |result, column|
       sum = total_sum_of(column)
       result[column] = sum unless sum.nil?

spec/features/work_packages/index_sums_spec.rb

@@ -29,18 +29,35 @@
 require 'spec_helper'
 
 RSpec.feature 'Work package index sums', js: true do
-
   let(:admin) { FactoryBot.create(:admin) }
-  let(:project) {
+  let(:project) do
     FactoryBot.create(:project, name: 'project1', identifier: 'project1')
-  }
-
-  let!(:work_package_1) {
-    FactoryBot.create(:work_package, project: project, estimated_hours: 10)
-  }
-  let!(:work_package_2) {
-    FactoryBot.create(:work_package, project: project, estimated_hours: 15)
-  }
+  end
+  let(:type) { FactoryBot.create(:type) }
+  let!(:int_cf) do
+    FactoryBot.create(:int_wp_custom_field).tap do |cf|
+      project.work_package_custom_fields << cf
+      type.custom_fields << cf
+    end
+  end
+  let!(:float_cf) do
+    FactoryBot.create(:float_wp_custom_field).tap do |cf|
+      project.work_package_custom_fields << cf
+      type.custom_fields << cf
+    end
+  end
+  let!(:work_package_1) do
+    FactoryBot.create(:work_package, project: project, type: type, estimated_hours: 10).tap do |wp|
+      wp.custom_field_values = { int_cf.id => 5, float_cf.id => 5.5 }
+      wp.save!
+    end
+  end
+  let!(:work_package_2) do
+    FactoryBot.create(:work_package, project: project, type: type, estimated_hours: 15).tap do |wp|
+      wp.custom_field_values = { int_cf.id => 7, float_cf.id => 7.7 }
+      wp.save!
+    end
+  end
 
   let(:wp_table) { Pages::WorkPackagesTable.new(project) }
   let(:columns) { ::Components::WorkPackages::Columns.new }
@@ -49,6 +66,10 @@ RSpec.feature 'Work package index sums', js: true do
   before do
     login_as(admin)
 
+    allow(Setting)
+      .to receive(:work_package_list_summable_columns)
+      .and_return(%W(estimated_hours cf_#{int_cf.id} cf_#{float_cf.id}))
+
     visit project_work_packages_path(project)
     expect(current_path).to eq('/projects/project1/work_packages')
   end
@@ -58,6 +79,10 @@ RSpec.feature 'Work package index sums', js: true do
 
     # Add estimated time column
     columns.add 'Estimated time'
+    # Add int cf column
+    columns.add int_cf.name
+    # Add float cf column
+    columns.add float_cf.name
 
     # Trigger action from action menu dropdown
     modal.set_display_sums enable: true
@@ -66,6 +91,8 @@ RSpec.feature 'Work package index sums', js: true do
 
     expect(page).to have_selector('.wp-table--sum-container', text: 'Sum')
     expect(page).to have_selector('.wp-table--sum-container', text: '25')
+    expect(page).to have_selector('.wp-table--sum-container', text: '12')
+    expect(page).to have_selector('.wp-table--sum-container', text: '13.2')
 
     # Update the sum
     edit_field = wp_table.edit_field(work_package_1, :estimatedTime)
@@ -73,5 +100,7 @@ RSpec.feature 'Work package index sums', js: true do
 
     expect(page).to have_selector('.wp-table--sum-container', text: 'Sum')
     expect(page).to have_selector('.wp-table--sum-container', text: '35')
+    expect(page).to have_selector('.wp-table--sum-container', text: '12')
+    expect(page).to have_selector('.wp-table--sum-container', text: '13.2')
   end
 end