Redirect Search to Form When No Product Results Are Found

pre_get_posts is fired before the query is run and is used to customize the query before its is run.

See here for a list of hooks, they are listed in order of execution. https://codex.wordpress.org/Plugin_API/Action_Reference

I would suggest using a hook that fires after the query is run for example, template_redirect is fired immediately after the query is run.

function no_products_found_redirect() {
    global $wp_query;

    if ( $wp_query->is_search && !have_posts() ){
        wp_redirect ( home_url('/request-quote/?product_name=" . get_search_query() ) );
        exit;
    }
}
add_action( "template_redirect', 'no_products_found_redirect' );

Related Posts:

  1. showing all search result in one template
  2. Extend product search with meta in WooCommerce
  3. Hide products in uncategorized category from search results
  4. $wp_query->found_posts not returning correct value
  5. Filtering product search results using tags
  6. Can I force WP_Query to return no results?
  7. WP Query where title begins with a specific letter
  8. Order Search Results Page by meta_value If no Value Return Remaining Results
  9. Query WooCommerce orders where meta data does not exist
  10. Tracing the life of a query
  11. Get WooCommerce best selling products for the current month [closed]
  12. Woocommerce query by price range and custom meta key
  13. Custom search form with empty parameters
  14. Find all product that contain terms with %keywords% in WP_Query
  15. WP Query – Get WooCommerce Products with variation that is in stock
  16. Multiple search queries on one page
  17. Search product by brand name in wp_query
  18. WP Query search for attachments and their exact title
  19. Including only current user’s posts in search
  20. Custom category search box for WordPress
  21. Refine search results using WP_Query
  22. Search Posts with Custom Fields as query
  23. Extending woocommerce admin product search
  24. Creating a custom search for a specific post type
  25. Assigning a meta_query value based on regexp to wp_query fails
  26. WC displaying products from category
  27. Is there any advantage of using default WordPress Search instead of creating a custom one?
  28. Get all products which have both product category
  29. Search for multiple tags?
  30. wp_query ‘s’, search filter with pagination is not working
  31. Sort by price woocommerce by ID post_meta
  32. Cluster WooCommerce products in each Category Archive by Tags assigned to products
  33. WP_QUERY to display woocommerce products whose author IS the logged in user
  34. Display filtered results into custom page
  35. WooCommerce – get product sub categories
  36. Cutom wp_query for geolocation search, pagination not working
  37. Search Query for multiple categories using ‘OR’ but having certain categories be ‘AND’
  38. Out Of memory issue on post per page parameter
  39. query_vars overriding WP_Query args
  40. Query with search and subscribers only output
  41. how can I override The Events Calendar query modifications?
  42. How do I get my custom query to work with search results after the first page?
  43. Modify Search Query if original Query gave no results
  44. Need Sub-category with main Category
  45. Woocommerce pagination and result count after custom loop
  46. Include post content of linked posts in search
  47. Replacing search results with custom external query
  48. Prevent author bio page from showing in search results
  49. How do I amend wp_query before it is run/executed?
  50. WordPress Custom Search Form Displaying Unexpected Results
  51. Can’t fetch Custom Post Type Data through Custom Query
  52. How to properly use AND / OR in custom search
  53. How do I get Woocommerce product variation name and variation description in a WP_Query?
  54. How to avoid bypass of search bar rules?
  55. How do you determine if a result in a search query is a post or a page?
  56. Slow Query On Search
  57. How To Keep Search Title the same on paged Results
  58. wp_query show all values
  59. WP_Query for products always returns empty
  60. How to restrict search on a certain page to only return results against custom taxonomies?
  61. Filter out a meta key in the Search results page with two CPT
  62. Query by key or author
  63. Ignore image urls in wp_query search
  64. Can I make a search query which includes a space?
  65. WordPress search WP_Query to cover multiple post types and their custom fields?
  66. My combination of ‘post_type’ and ‘tax_query’ not working?
  67. Woocommerce Get Orders By Meta Value
  68. Save large WP_Query to transient === false
  69. Custom Woocommerce Product Query
  70. WP_Query no result if keyword contains number
  71. Multiple WP_Query args combinations according to post type
  72. WooCommerce WP_Query using tax_query returns no results (0 = 1)
  73. How sort products by calculate value? ( custom post meta, price, option)
  74. wc_get_products() return empty object
  75. WooCommerce. How To Exclude Subcategory Products From Category Listing Page
  76. get_posts return only first result
  77. How to display Woocommerce products list by tag
  78. Display the search results like the original pages
  79. How to use jQuery validation to set the search bar to accept only a specific input?
  80. Woocommerce featured products query no longer working
  81. update_post_meta performance in a loop woocommerce
  82. update_post_meta performance in a loop woocommerce
  83. getting posts by tags
  84. Query child posts with tax query on parents
  85. Custom Post Type WP_Query with filters and search
  86. WordPress search page pagination displaying but not functional
  87. Search has query that will return no results
  88. WP Query – Search in title or author_name
  89. Get posts by similar names and categories
  90. How do i query woocommerce booking post type on init action?
  91. Order & Orderby clause not working with custom query
  92. How can I modify standard search query to include also ACF custom fields values?
  93. Woocommerce orderby rand with tax_query not random
  94. $wp_query when new WP_Query
  95. Need help setting up a search form for wordpress [duplicate]
  96. Show linked products using wp query and woocommerce
  97. WordPress WP_Query Search (‘s’) With Multiple Search Terms
  98. How does Show Posts based on a keyword search work in WP_Query
  99. Search results stuck on page 1
  100. Custom Taxonomy in custom REST API search