fix(server): return empty summary field value (#12517)

close AF-2658

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **Tests**
  - Added new test cases and snapshots to enhance coverage for search results involving empty or missing fields like summary, title, and ref_doc_id.
  - Verified consistent handling of empty string values and absence of fields across different search providers.

- **Bug Fixes**
  - Improved handling of empty string values for specific fields by converting them to null to ensure consistent search result formatting.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/__tests__/e2e/indexer/__snapshots__/search.spec.ts.md

@@ -138,3 +138,35 @@ Generated by [AVA](https://avajs.dev).
         },
       },
     }
+
+## should return empty nodes when docId not exists
+
+> Snapshot 1
+
+    {
+      workspace: {
+        search: {
+          nodes: [],
+          pagination: {
+            count: 0,
+            hasMore: false,
+            nextCursor: null,
+          },
+        },
+      },
+    }
+
+## should empty doc summary string when doc exists but no summary
+
+> Snapshot 1
+
+    [
+      {
+        fields: {
+          summary: [
+            '',
+          ],
+        },
+        highlights: null,
+      },
+    ]

packages/backend/server/src/__tests__/e2e/indexer/search.spec.ts

@@ -276,3 +276,87 @@ e2e('should return empty results when search not match any docs', async t => {
 
   t.snapshot(result);
 });
+
+e2e('should return empty nodes when docId not exists', async t => {
+  const owner = await app.signup();
+  const workspace = await app.create(Mockers.Workspace, {
+    owner,
+  });
+
+  const result = await app.gql({
+    query: indexerSearchQuery,
+    variables: {
+      id: workspace.id,
+      input: {
+        table: SearchTable.doc,
+        query: {
+          type: SearchQueryType.match,
+          field: 'docId',
+          match: 'not-exists-doc-id',
+        },
+        options: {
+          fields: ['summary'],
+          pagination: {
+            limit: 1,
+          },
+        },
+      },
+    },
+  });
+
+  t.snapshot(result);
+});
+
+e2e(
+  'should empty doc summary string when doc exists but no summary',
+  async t => {
+    const owner = await app.signup();
+    const workspace = await app.create(Mockers.Workspace, {
+      owner,
+    });
+
+    const indexerService = app.get(IndexerService);
+
+    await indexerService.write(
+      SearchTable.doc,
+      [
+        {
+          docId: 'doc-1-without-summary',
+          workspaceId: workspace.id,
+          title: 'test1',
+          summary: '',
+          createdByUserId: owner.id,
+          updatedByUserId: owner.id,
+          createdAt: new Date('2025-04-22T00:00:00.000Z'),
+          updatedAt: new Date('2025-04-22T00:00:00.000Z'),
+        },
+      ],
+      {
+        refresh: true,
+      }
+    );
+
+    const result = await app.gql({
+      query: indexerSearchQuery,
+      variables: {
+        id: workspace.id,
+        input: {
+          table: SearchTable.doc,
+          query: {
+            type: SearchQueryType.match,
+            field: 'docId',
+            match: 'doc-1-without-summary',
+          },
+          options: {
+            fields: ['summary'],
+            pagination: {
+              limit: 1,
+            },
+          },
+        },
+      },
+    });
+
+    t.snapshot(result.workspace.search.nodes);
+  }
+);

packages/backend/server/src/plugins/indexer/__tests__/providers/__snapshots__/elasticsearch.spec.ts.md

@@ -494,6 +494,55 @@ Generated by [AVA](https://avajs.dev).
       },
     }
 
+## should return empty string field:summary value
+
+> Snapshot 1
+
+    [
+      {
+        _id: 'workspaceId-search-query-return-empty-string-field-summary-value-for-elasticsearch/doc0',
+        _source: {
+          doc_id: 'doc0',
+          workspace_id: 'workspaceId-search-query-return-empty-string-field-summary-value-for-elasticsearch',
+        },
+        fields: {
+          doc_id: [
+            'doc0',
+          ],
+          summary: [
+            '',
+          ],
+          title: [
+            '',
+          ],
+        },
+        highlights: undefined,
+      },
+    ]
+
+## should not return not exists field:ref_doc_id
+
+> Snapshot 1
+
+    [
+      {
+        _id: 'workspaceId-search-query-not-return-not-exists-field-ref_doc_id-for-elasticsearch/doc0/block0',
+        _source: {
+          doc_id: 'doc0',
+          workspace_id: 'workspaceId-search-query-not-return-not-exists-field-ref_doc_id-for-elasticsearch',
+        },
+        fields: {
+          block_id: [
+            'block0',
+          ],
+          doc_id: [
+            'doc0',
+          ],
+        },
+        highlights: undefined,
+      },
+    ]
+
 ## should aggregate query work
 
 > Snapshot 1

packages/backend/server/src/plugins/indexer/__tests__/providers/__snapshots__/manticoresearch.spec.ts.md

@@ -9,6 +9,9 @@ Generated by [AVA](https://avajs.dev).
 > Snapshot 1
 
     {
+      block_id: [
+        '',
+      ],
       content: [
         'hello world',
       ],
@@ -29,6 +32,9 @@ Generated by [AVA](https://avajs.dev).
 > Snapshot 2
 
     {
+      block_id: [
+        '',
+      ],
       content: [
         'hello world',
       ],
@@ -43,6 +49,9 @@ Generated by [AVA](https://avajs.dev).
 > Snapshot 3
 
     {
+      block_id: [
+        '',
+      ],
       content: [
         'hello world',
       ],
@@ -239,6 +248,9 @@ Generated by [AVA](https://avajs.dev).
           blob: [
             'blob1',
           ],
+          content: [
+            '',
+          ],
           flavour: [
             'affine:page',
           ],
@@ -262,6 +274,9 @@ Generated by [AVA](https://avajs.dev).
             'blob1',
             'blob2',
           ],
+          content: [
+            '',
+          ],
           flavour: [
             'affine:page',
           ],
@@ -284,6 +299,9 @@ Generated by [AVA](https://avajs.dev).
           blob: [
             'blob3',
           ],
+          content: [
+            '',
+          ],
           flavour: [
             'affine:page',
           ],
@@ -687,6 +705,55 @@ Generated by [AVA](https://avajs.dev).
       },
     ]
 
+## should return empty string field:summary value
+
+> Snapshot 1
+
+    [
+      {
+        _id: '274027293861775228',
+        _source: {
+          doc_id: 'doc0',
+          workspace_id: 'workspaceId-search-query-return-empty-string-field-summary-value-for-manticoresearch',
+        },
+        fields: {
+          doc_id: [
+            'doc0',
+          ],
+          summary: [
+            '',
+          ],
+          title: [
+            '',
+          ],
+        },
+        highlights: undefined,
+      },
+    ]
+
+## should not return not exists field:ref_doc_id
+
+> Snapshot 1
+
+    [
+      {
+        _id: '2457631367295327017',
+        _source: {
+          doc_id: 'doc0',
+          workspace_id: 'workspaceId-search-query-not-return-not-exists-field-ref_doc_id-for-manticoresearch',
+        },
+        fields: {
+          block_id: [
+            'block0',
+          ],
+          doc_id: [
+            'doc0',
+          ],
+        },
+        highlights: undefined,
+      },
+    ]
+
 ## should aggregate query return top score first
 
 > Snapshot 1

packages/backend/server/src/plugins/indexer/__tests__/providers/elasticsearch.spec.ts

@@ -1303,6 +1303,113 @@ test('should search doc title support stemmer filter', async t => {
   t.snapshot(omit(result.nodes[0], ['_score']));
 });
 
+test('should return empty string field:summary value', async t => {
+  const workspaceId =
+    'workspaceId-search-query-return-empty-string-field-summary-value-for-elasticsearch';
+  const docId = 'doc0';
+
+  await searchProvider.write(
+    SearchTable.doc,
+    [
+      {
+        workspace_id: workspaceId,
+        doc_id: docId,
+        title: '',
+        summary: '',
+        created_by_user_id: user.id,
+        updated_by_user_id: user.id,
+        created_at: new Date(),
+        updated_at: new Date(),
+      },
+    ],
+    {
+      refresh: true,
+    }
+  );
+
+  let result = await searchProvider.search(SearchTable.doc, {
+    _source: ['workspace_id', 'doc_id'],
+    query: {
+      bool: {
+        must: [
+          {
+            term: { workspace_id: { value: workspaceId } },
+          },
+          {
+            term: {
+              doc_id: {
+                value: docId,
+              },
+            },
+          },
+        ],
+      },
+    },
+    fields: ['doc_id', 'title', 'summary'],
+    sort: ['_score'],
+  });
+
+  t.snapshot(result.nodes.map(node => omit(node, ['_score'])));
+});
+
+test('should not return not exists field:ref_doc_id', async t => {
+  const workspaceId =
+    'workspaceId-search-query-not-return-not-exists-field-ref_doc_id-for-elasticsearch';
+  const docId = 'doc0';
+  const blockId = 'block0';
+
+  await searchProvider.write(
+    SearchTable.block,
+    [
+      {
+        workspace_id: workspaceId,
+        doc_id: docId,
+        block_id: blockId,
+        content: 'hello world on search title blockId1-text',
+        flavour: 'affine:text',
+        created_by_user_id: user.id,
+        updated_by_user_id: user.id,
+        created_at: new Date(),
+        updated_at: new Date(),
+      },
+    ],
+    {
+      refresh: true,
+    }
+  );
+
+  let result = await searchProvider.search(SearchTable.block, {
+    _source: ['workspace_id', 'doc_id'],
+    query: {
+      bool: {
+        must: [
+          {
+            term: { workspace_id: { value: workspaceId } },
+          },
+          {
+            term: {
+              doc_id: {
+                value: docId,
+              },
+            },
+          },
+        ],
+      },
+    },
+    fields: [
+      'doc_id',
+      'block_id',
+      'ref_doc_id',
+      'parent_block_id',
+      'additional',
+      'parent_flavour',
+    ],
+    sort: ['_score'],
+  });
+
+  t.snapshot(result.nodes.map(node => omit(node, ['_score'])));
+});
+
 // #endregion
 
 // #region aggregate

packages/backend/server/src/plugins/indexer/__tests__/providers/manticoresearch.spec.ts

@@ -1065,6 +1065,113 @@ test('should search query match ref_doc_id work', async t => {
   t.is(result.total, 2);
 });
 
+test('should return empty string field:summary value', async t => {
+  const workspaceId =
+    'workspaceId-search-query-return-empty-string-field-summary-value-for-manticoresearch';
+  const docId = 'doc0';
+
+  await searchProvider.write(
+    SearchTable.doc,
+    [
+      {
+        workspace_id: workspaceId,
+        doc_id: docId,
+        title: '',
+        summary: '',
+        created_by_user_id: user.id,
+        updated_by_user_id: user.id,
+        created_at: new Date(),
+        updated_at: new Date(),
+      },
+    ],
+    {
+      refresh: true,
+    }
+  );
+
+  let result = await searchProvider.search(SearchTable.doc, {
+    _source: ['workspace_id', 'doc_id'],
+    query: {
+      bool: {
+        must: [
+          {
+            term: { workspace_id: { value: workspaceId } },
+          },
+          {
+            term: {
+              doc_id: {
+                value: docId,
+              },
+            },
+          },
+        ],
+      },
+    },
+    fields: ['doc_id', 'title', 'summary'],
+    sort: ['_score'],
+  });
+
+  t.snapshot(result.nodes.map(node => omit(node, ['_score'])));
+});
+
+test('should not return not exists field:ref_doc_id', async t => {
+  const workspaceId =
+    'workspaceId-search-query-not-return-not-exists-field-ref_doc_id-for-manticoresearch';
+  const docId = 'doc0';
+  const blockId = 'block0';
+
+  await searchProvider.write(
+    SearchTable.block,
+    [
+      {
+        workspace_id: workspaceId,
+        doc_id: docId,
+        block_id: blockId,
+        content: 'hello world on search title blockId1-text',
+        flavour: 'affine:text',
+        created_by_user_id: user.id,
+        updated_by_user_id: user.id,
+        created_at: new Date(),
+        updated_at: new Date(),
+      },
+    ],
+    {
+      refresh: true,
+    }
+  );
+
+  let result = await searchProvider.search(SearchTable.block, {
+    _source: ['workspace_id', 'doc_id'],
+    query: {
+      bool: {
+        must: [
+          {
+            term: { workspace_id: { value: workspaceId } },
+          },
+          {
+            term: {
+              doc_id: {
+                value: docId,
+              },
+            },
+          },
+        ],
+      },
+    },
+    fields: [
+      'doc_id',
+      'block_id',
+      'ref_doc_id',
+      'parent_block_id',
+      'additional',
+      'parent_flavour',
+    ],
+    sort: ['_score'],
+  });
+
+  t.snapshot(result.nodes.map(node => omit(node, ['_score'])));
+});
+
 // #endregion
 
 // #region aggregate

packages/backend/server/src/plugins/indexer/providers/manticoresearch.ts

@@ -38,6 +38,15 @@ const SupportIndexedAttributes = [
   'parent_block_id',
 ];
 
+const ConvertEmptyStringToNullValueFields = new Set([
+  'ref_doc_id',
+  'ref',
+  'blob',
+  'additional',
+  'parent_block_id',
+  'parent_flavour',
+]);
+
 @Injectable()
 export class ManticoresearchProvider extends ElasticsearchProvider {
   override type = SearchProviderType.Manticoresearch;
@@ -344,7 +353,10 @@ export class ManticoresearchProvider extends ElasticsearchProvider {
     return fields.reduce(
       (acc, field) => {
         let value = source[field];
-        if (value !== null && value !== undefined && value !== '') {
+        if (ConvertEmptyStringToNullValueFields.has(field) && value === '') {
+          value = null;
+        }
+        if (value !== null && value !== undefined) {
           // special handle `ref_doc_id`, `ref`, `blob` as string[]
           if (
             (field === 'ref_doc_id' || field === 'ref' || field === 'blob') &&