MM-24530-Add support for search terms with underscore using postgresql engine (#16618)

* add support for search terms with underscore using postgresql

* fix failing tests

Initially issue fix applied to all search terms instead of the ones that contains _

* direct cast tsquery

* fix test issues

* refactor underscored quoted term search

* support search term case-insensitive

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/post_test.go

@@ -2249,6 +2249,27 @@ func TestSearchHashtagPosts(t *testing.T) {
 	CheckUnauthorizedStatus(t, resp)
 }
 
+func TestSearchUnderscorePosts(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+	th.LoginBasic()
+	Client := th.Client
+
+	message := "test_with_underscore"
+	assert.NotNil(t, th.CreateMessagePost(message))
+
+	message = " test with underscore"
+	assert.NotNil(t, th.CreateMessagePost(message))
+
+	posts, resp := Client.SearchPosts(th.BasicTeam.Id, "test_with_underscore", false)
+	CheckNoError(t, resp)
+	require.Len(t, posts.Order, 1, "wrong search results")
+
+	Client.Logout()
+	_, resp = Client.SearchPosts(th.BasicTeam.Id, "#sgtitlereview", false)
+	CheckUnauthorizedStatus(t, resp)
+}
+
 func TestSearchPostsInChannel(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()

store/searchtest/post_layer.go

@@ -215,7 +215,7 @@ var searchPostStoreTests = []searchTest{
 	{
 		Name: "Should be able to search terms with underscores",
 		Fn:   testSearchTermsWithUnderscores,
-		Tags: []string{EngineMySql, EngineElasticSearch},
+		Tags: []string{EngineAll},
 	},
 	{
 		Name: "Should be able to search posts made by bot accounts",

store/sqlstore/post_store.go

@@ -1481,7 +1481,16 @@ func (s *SqlPostStore) search(teamId string, userId string, params *model.Search
 			queryParams["Terms"] = "(" + strings.Join(strings.Fields(terms), " & ") + ")" + excludeClause
 		}
 
-		searchClause := fmt.Sprintf("AND to_tsvector('english', %s) @@  to_tsquery('english', :Terms)", searchType)
+		searchClause := ""
+		if strings.Contains(terms, "_") {
+			//Strip quotes off terms with it
+			if strings.Contains(terms, "\"") {
+				queryParams["Terms"] = strings.ReplaceAll(queryParams["Terms"].(string), "\"", "")
+			}
+			searchClause = fmt.Sprintf("AND lower(%s)::tsvector @@ lower(:Terms)::tsquery", searchType)
+		} else {
+			searchClause = fmt.Sprintf("AND to_tsvector('english', %s) @@  to_tsquery('english', :Terms)", searchType)
+		}
 		searchQuery = strings.Replace(searchQuery, "SEARCH_CLAUSE", searchClause, 1)
 	} else if s.DriverName() == model.DATABASE_DRIVER_MYSQL {
 		if searchType == "Message" {