feat: total pages returned from paging results (#2669)

src/main/java/run/halo/app/extension/ListResult.java

@@ -67,8 +67,7 @@ public class ListResult<T> implements Streamable<T> {
         if (page <= 0) {
             return false;
         }
-        var totalPages = size == 0 ? 1 : (int) Math.ceil((double) total / (double) size);
+        return page < getTotalPages();
-        return page < totalPages;
     }
 
     @Schema(description = "Indicates whether current page has previous page.", required = true)
@@ -88,6 +87,12 @@ public class ListResult<T> implements Streamable<T> {
         return Streamable.super.isEmpty();
     }
 
+    @Schema(description = "Indicates total pages.", required = true)
+    @JsonProperty("totalPages")
+    public long getTotalPages() {
+        return size == 0 ? 1 : (total + size - 1) / size;
+    }
+
     /**
      * Generate generic ListResult class. Like {@code ListResult<User>}, {@code ListResult<Post>},
      * etc.

src/test/java/run/halo/app/content/comment/CommentServiceImplTest.java

@@ -244,6 +244,7 @@ class CommentServiceImplTest {
                 "page": 1,
                 "size": 10,
                 "total": 3,
+                "totalPages": 1,
                 "items": [
                     {
                         "comment": {

src/test/java/run/halo/app/extension/ListResultTest.java

@@ -5,6 +5,7 @@ import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.lang.reflect.ParameterizedType;
+import java.util.List;
 import org.junit.jupiter.api.Test;
 
 class ListResultTest {
@@ -27,4 +28,19 @@ class ListResultTest {
             .getActualTypeArguments()[0]);
         assertEquals("FakeExtensionList", fakeListClass.getSimpleName());
     }
+
+    @Test
+    void totalPages() {
+        var listResult = new ListResult<>(1, 10, 100, List.of());
+        assertEquals(10, listResult.getTotalPages());
+
+        listResult = new ListResult<>(1, 10, 1, List.of());
+        assertEquals(1, listResult.getTotalPages());
+
+        listResult = new ListResult<>(1, 10, 9, List.of());
+        assertEquals(1, listResult.getTotalPages());
+
+        listResult = new ListResult<>(1, 0, 100, List.of());
+        assertEquals(1, listResult.getTotalPages());
+    }
 }