Fix issue#177

src/main/java/run/halo/app/service/impl/BaseCommentServiceImpl.java

@@ -429,6 +429,11 @@ public abstract class BaseCommentServiceImpl<COMMENT extends BaseComment> extend
         // Get all comments
         Page<COMMENT> topCommentPage = baseCommentRepository.findAllByPostIdAndStatusAndParentId(targetId, status, 0L, pageable);
 
+        if (topCommentPage.isEmpty()) {
+            // If the comments is empty
+            return ServiceUtils.buildEmptyPageImpl(topCommentPage);
+        }
+
         // Get top comment ids
         Set<Long> topCommentIds = ServiceUtils.fetchProperty(topCommentPage.getContent(), BaseComment::getId);
 

src/main/java/run/halo/app/utils/ServiceUtils.java

@@ -1,8 +1,6 @@
 package run.halo.app.utils;
 
-import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.*;
-import org.springframework.data.domain.Pageable;
-import org.springframework.data.domain.Sort;
 import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
@@ -136,6 +134,21 @@ public class ServiceUtils {
         return buildLatestPageable(top, "createTime");
     }
 
+    /**
+     * Build empty page result.
+     *
+     * @param page page info must not be null
+     * @param <T>  target page result type
+     * @param <S>  source page result type
+     * @return empty page result
+     */
+    @NonNull
+    public static <T, S> Page<T> buildEmptyPageImpl(@NonNull Page<S> page) {
+        Assert.notNull(page, "Page result must not be null");
+
+        return new PageImpl<>(Collections.emptyList(), page.getPageable(), page.getTotalElements());
+    }
+
     /**
      * Builds latest page request.
      *