#12717 - Catalog Products List widget is not displayed on Storefront

[RostislavS]

Description

Problem is that when flats are enabled, logic does not check if an attribute is actually present in flat table. Added a check that the attribute is in flat and if not, we join this attribute.

Fixed Issues (if relevant)

1. Catalog Products List widget is not displayed on Storefront #12717: Catalog Products List widget is not displayed on Storefront

Manual testing scenarios

Go to Stores > Attributes > Product and open "Color" attribute
Create 2 options red and black
Add this attribute to attribute set
Create 2 simple products with red and black attributes
Go to Stores> Configuration > CATALOG > Catalog > Storefront
Set "Use Flat Catalog Category" = Yes and "Use Flat Catalog Product" = "Yes"
Go to Content > Widgets and create new widget with:
Storefront Properties
Widget Title = Test widget
Assign to Store Views = All Store Views
Layout Updates:
-- Display on = All Pages
-- Container = Main Content Area
Widget Options

Title = test
Number of Products to Display = 10
Conditions: Color is red
run
rm -rf var/* pub/static/* generated/*
php bin/magento indexer:reindex
php bin/magento setup:static-content:deploy
Go to Storefront
Expected result

Widget is visible on Storefront

Actual result

Widget is not visible on Storefront, following error persists in support_report.log:
report.CRITICAL: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'at_color.value' in 'where clause', query was: SELECT COUNT(DISTINCT e.entity_id) FROM catalog_product_flat_1 AS e
INNER JOIN catalog_category_product_index AS cat_index ON cat_index.product_id=e.entity_id AND cat_index.store_id='1' AND cat_index.visibility IN(2, 4) AND cat_index.category_id='2'
INNER JOIN catalog_product_index_price AS price_index ON price_index.entity_id = e.entity_id AND price_index.website_id = '1' AND price_index.customer_group_id = 0 WHERE (((IFNULL(at_color.value, 0) = '13') ))

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-cicd2]

All committers have signed the CLA.

[dmanners]

Hi @RostislavS sorry for the delay in processing this pull request. I will have a look at it now and get back to you if I need any thing more.