[TEAMMATES#11302] Increase search result limit with message prompt wh…

…en limit is reached (TEAMMATES#11324)

* Increase search result limit with message prompt when limit is reached

* Fix linting errors

* Update snapshots to match UI changes

* Reduce if-statement nesting

* Fix linting issues

* Fix typo in message prompt

* Shift query size value to backend and show individual prompts for instructor and student search

* Fix linting errors

* Rename query size limit constant

* Clean up code to reduce repetition

* Update failing snapshots for admin search page

* Clean up code for search limit message

src/main/java/teammates/common/util/Const.java

@@ -33,6 +33,8 @@ public final class Const {
     public static final Duration FEEDBACK_SESSIONS_SEARCH_WINDOW = Duration.ofDays(30);
     public static final Duration LOGS_RETENTION_PERIOD = Duration.ofDays(30);
 
+    public static final int SEARCH_QUERY_SIZE_LIMIT = 50;
+
     // These constants are used as variable values to mean that the variable is in a 'special' state.
 
     public static final int INT_UNINITIALIZED = -9999;

src/main/java/teammates/storage/search/SearchManager.java

@@ -19,6 +19,7 @@
 import teammates.common.datatransfer.attributes.EntityAttributes;
 import teammates.common.exception.SearchServiceException;
 import teammates.common.util.Config;
+import teammates.common.util.Const;
 import teammates.common.util.Logger;
 import teammates.common.util.StringHelper;
 
@@ -43,7 +44,7 @@ abstract class SearchManager<T extends EntityAttributes<?>> {
             "Failed to reset collections. Root cause: %s ";
 
     private static final int START_INDEX = 0;
-    private static final int NUM_OF_RESULTS = 20;
+    private static final int NUM_OF_RESULTS = Const.SEARCH_QUERY_SIZE_LIMIT;
 
     private final HttpSolrClient client;
     private final boolean isResetAllowed;

src/main/java/teammates/ui/constants/ApiConst.java

@@ -26,7 +26,8 @@ public enum ApiConst {
     RANK_OPTIONS_ANSWER_NOT_SUBMITTED(Const.POINTS_NOT_SUBMITTED),
     RANK_RECIPIENTS_ANSWER_NOT_SUBMITTED(Const.POINTS_NOT_SUBMITTED),
     NO_VALUE(Const.POINTS_NO_VALUE),
-    LOGS_RETENTION_PERIOD(Const.LOGS_RETENTION_PERIOD.toDays());
+    LOGS_RETENTION_PERIOD(Const.LOGS_RETENTION_PERIOD.toDays()),
+    SEARCH_QUERY_SIZE_LIMIT(Const.SEARCH_QUERY_SIZE_LIMIT);
     // CHECKSTYLE.ON:JavadocVariable
 
     private final Object value;

src/web/app/pages-admin/admin-search-page/admin-search-page.component.ts

@@ -15,6 +15,7 @@ import {
 import { SimpleModalService } from '../../../services/simple-modal.service';
 import { StatusMessageService } from '../../../services/status-message.service';
 import { StudentService } from '../../../services/student.service';
+import { ApiConst } from '../../../types/api-const';
 import { Email, RegenerateKey } from '../../../types/api-output';
 import { SimpleModalType } from '../../components/simple-modal/simple-modal-type';
 import { collapseAnim } from '../../components/teammates-common/collapse-anim';
@@ -61,12 +62,28 @@ export class AdminSearchPageComponent {
         this.statusMessageService.showWarningToast('No results found.');
         this.instructors = [];
         this.students = [];
-      } else {
-        this.instructors = resp.instructors;
-        this.students = resp.students;
-        this.hideAllInstructorsLinks();
-        this.hideAllStudentsLinks();
+        return;
       }
+
+      this.instructors = resp.instructors;
+      this.students = resp.students;
+      this.hideAllInstructorsLinks();
+      this.hideAllStudentsLinks();
+
+      // prompt user to use more specific terms if search results limit reached
+      const limit: number = ApiConst.SEARCH_QUERY_SIZE_LIMIT;
+      const limitsReached: string[] = [];
+      if (this.students.length >= limit) {
+        limitsReached.push(`${limit} student results`);
+      }
+      if (this.instructors.length >= limit) {
+        limitsReached.push(`${limit} instructor results`);
+      }
+      if (limitsReached.length) {
+        this.statusMessageService.showWarningToast(`${limitsReached.join(' and ')} have been shown on this page
+            but there may be more results not shown. Consider searching with more specific terms.`);
+      }
+
     }, (resp: ErrorMessageOutput) => {
       this.instructors = [];
       this.students = [];

src/web/app/pages-instructor/instructor-search-page/instructor-search-page.component.ts

@@ -4,6 +4,7 @@ import { finalize, map, mergeMap } from 'rxjs/operators';
 import { CourseService } from '../../../services/course.service';
 import { InstructorSearchResult, SearchService } from '../../../services/search.service';
 import { StatusMessageService } from '../../../services/status-message.service';
+import { ApiConst } from '../../../types/api-const';
 import {
   InstructorPrivilege,
   Student,
@@ -64,6 +65,10 @@ export class InstructorSearchPageComponent implements OnInit {
 
       if (hasStudents) {
         this.studentsListRowTables = searchStudentsTable;
+        if (searchStudentsTable.length >= ApiConst.SEARCH_QUERY_SIZE_LIMIT) {
+          this.statusMessageService.showWarningToast(`${ApiConst.SEARCH_QUERY_SIZE_LIMIT} results have been shown on this page
+              but there may be more results not shown. Consider searching with more specific terms.`);
+        }
       } else {
         this.studentsListRowTables = [];
       }