Search with OR condition

To demonstrate the difference, lets first seach for all products which has a common parent.

Following example shows a method that will search for all the products under a given product group, (even products under sub-product groups are included)

        /// <summary>
        /// Searches for  products (and variant groups) under a product group.
        /// </summary>
        /// <param name="languageId">The language id.</param>
        /// <param name="productGroupId">The product group id.</param>
        /// <param name="token">The token.</param>
        /// <returns></returns>
        public static IEnumerable<Guid> SearchForProducts(Guid languageId, Guid productGroupId, SecurityToken token)
        {
            IEnumerable<Guid> result = null;
            var request = new QueryRequest(languageId, ProductCatalogSearchDomains.Products, token);
            //search for all products and variant groups who has a parent with above product group id.
            request.FilterTags.Add(new Tag(TagNames.ProductGroupTreeId, productGroupId));

            var response = Solution.Instance.SearchService.Search(request);
            if (response.Hits != null)
            {
                result = response.Hits.Select(x => new Guid(x.Id));
            }
            return result ?? new List<Guid>();
        }

The above example searches only under a single product group. We can extend the search to return results searching under multiple product groups by using the OptionalTagClause as shown below.

        /// <summary>
        /// Searches for products (and variant groups) under all the product groups in parameter <paramref name="productGroupIds"/>
        /// </summary>
        /// <param name="languageId">The language id.</param>
        /// <param name="productGroupIds">The product group ids.</param>
        /// <param name="token">The token.</param>
        /// <returns></returns>
        public static IEnumerable<Guid> SearchForProducts(Guid languageId, List<Guid> productGroupIds, SecurityToken token)
        {
            IEnumerable<Guid> result = null;
            var request = new QueryRequest(languageId, ProductCatalogSearchDomains.Products, token);

            //search for all products and variant groups who has a parent with given groups.
            var productGroupClause = new OptionalTagClause();
            foreach (var item in productGroupIds)
            {
                productGroupClause.FilterTags.Add(new Tag(TagNames.ProductGroupTreeId, item));
            }
            request.FilterTags.Add(productGroupClause);

            var response = Solution.Instance.SearchService.Search(request);
            if (response.Hits != null)
            {
                result = response.Hits.Select(x => new Guid(x.Id));
            }
            return result ?? new List<Guid>();
        }