diff --git a/es/store.js b/es/store.js
index 2388a2d..05009bb 100644
--- a/es/store.js
+++ b/es/store.js
@@ -566,6 +566,16 @@ export default class TreeStore extends CascadeStore {
                     }).length > 0;
                 };
             }
+            case '$length': {
+                // json中的数组长度查询
+                const length = value;
+                assert(typeof length === 'number');
+                return (row) => {
+                    const data = path ? get(row, path) : row;
+                    assert(data instanceof Array, '$length operator can only used on array attribute');
+                    return data.length === length;
+                };
+            }
             default: {
                 throw new Error(`predicate ${predicate} is not recoganized`);
             }
diff --git a/lib/store.js b/lib/store.js
index 06b5a9c..7addd51 100644
--- a/lib/store.js
+++ b/lib/store.js
@@ -568,6 +568,16 @@ class TreeStore extends CascadeStore_1.CascadeStore {
                     }).length > 0;
                 };
             }
+            case '$length': {
+                // json中的数组长度查询
+                const length = value;
+                (0, assert_1.assert)(typeof length === 'number');
+                return (row) => {
+                    const data = path ? (0, lodash_1.get)(row, path) : row;
+                    (0, assert_1.assert)(data instanceof Array, '$length operator can only used on array attribute');
+                    return data.length === length;
+                };
+            }
             default: {
                 throw new Error(`predicate ${predicate} is not recoganized`);
             }
diff --git a/src/store.ts b/src/store.ts
index c1f95fa..62dfdab 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -707,6 +707,16 @@ export default class TreeStore<ED extends EntityDict & BaseEntityDict> extends C
                     }).length > 0;
                 };
             }
+            case '$length': {
+                // json中的数组长度查询
+                const length = value;
+                assert (typeof length === 'number');
+                return (row) => {
+                    const data = path ? get(row, path) : row;
+                    assert(data instanceof Array, '$length operator can only used on array attribute');
+                    return data.length === length;
+                }
+            }
             default: {
                 throw new Error(`predicate ${predicate} is not recoganized`);
             }
@@ -2281,7 +2291,7 @@ export default class TreeStore<ED extends EntityDict & BaseEntityDict> extends C
                             }
                             else if (this.store[entity]?.[id]) {
                                 const row = this.constructRow(this.store[entity]![id]!, context);
-                                if ((row[UpdateAtAttribute] as number) <= (d[entity]![id]![UpdateAtAttribute] as number)) {
+                                if ((row![UpdateAtAttribute] as number) <= (d[entity]![id]![UpdateAtAttribute] as number)) {
                                     this.updateAbjointRow(entity, {
                                         id: 'dummy',
                                         action: 'update',
diff --git a/test/test.ts b/test/test.ts
index 78422c4..f1f7eb2 100644
--- a/test/test.ts
+++ b/test/test.ts
@@ -1317,6 +1317,24 @@ describe('基础测试', function () {
             }
         }, context, {});
 
+        
+        const row12 = store.select('oper', {
+            data: {
+                id: 1,
+                data: {
+                    name: 1,
+                    price: 1,
+                },
+            },
+            filter: {
+                id,
+                data: {
+                    price: {
+                        $length: 3,
+                    },
+                }
+            }
+        }, context, {});
         context.commit();
         assert(row.length === 1);
         assert(row2.length === 0);
@@ -1329,6 +1347,7 @@ describe('基础测试', function () {
         assert(row9.length === 1);
         assert(row10.length === 1);
         assert(row11.length === 0);
+        assert(row12.length === 1);
         // console.log(JSON.stringify(row7));
     });