[database] Fix DatabaseQuery/DatabaseQueryModifiers incorrectly mutating previous query instances when chaining

packages/database/e2e/query/query.e2e.js

@@ -0,0 +1,30 @@
+/*
+ *  Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this library except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+describe('DatabaseQuery/DatabaseQueryModifiers', () => {
+  it('should not mutate previous queries (#2691)', async () => {
+    const queryBefore = firebase.database().ref();
+    queryBefore._modifiers._modifiers.length.should.equal(0);
+
+    const queryAfter = queryBefore.orderByChild('age');
+    queryBefore._modifiers._modifiers.length.should.equal(0);
+    queryAfter._modifiers._modifiers.length.should.equal(1);
+
+    const queryAfterAfter = queryAfter.equalTo(30);
+    queryAfter._modifiers._modifiers.length.should.equal(1);
+    queryAfterAfter._modifiers._modifiers.length.should.equal(3); // adds startAt endAt internally
+  });
+});

packages/database/lib/DatabaseQuery.js

@@ -80,7 +80,7 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    const modifiers = this._modifiers.endAt(value, key);
+    const modifiers = this._modifiers._copy().endAt(value, key);
     modifiers.validateModifiers('firebase.database().ref().endAt()');
 
     return new DatabaseQuery(this._database, this.path, modifiers);
@@ -155,7 +155,11 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    return new DatabaseQuery(this._database, this.path, this._modifiers.limitToFirst(limit));
+    return new DatabaseQuery(
+      this._database,
+      this.path,
+      this._modifiers._copy().limitToFirst(limit),
+    );
   }
 
   /**
@@ -176,7 +180,11 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    return new DatabaseQuery(this._database, this.path, this._modifiers.limitToLast(limit));
+    return new DatabaseQuery(
+      this._database,
+      this.path,
+      this._modifiers._copy().limitToLast(limit),
+    );
   }
 
   /**
@@ -369,7 +377,7 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    const modifiers = this._modifiers.toArray();
+    const modifiers = this._modifiers._copy().toArray();
 
     return this._database.native
       .once(this.path, modifiers, eventType)
@@ -425,7 +433,7 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    const modifiers = this._modifiers.orderByChild(path);
+    const modifiers = this._modifiers._copy().orderByChild(path);
     modifiers.validateModifiers('firebase.database().ref().orderByChild()');
 
     return new DatabaseQuery(this._database, this.path, modifiers);
@@ -441,7 +449,7 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    const modifiers = this._modifiers.orderByKey();
+    const modifiers = this._modifiers._copy().orderByKey();
     modifiers.validateModifiers('firebase.database().ref().orderByKey()');
 
     return new DatabaseQuery(this._database, this.path, modifiers);
@@ -457,7 +465,7 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    const modifiers = this._modifiers.orderByPriority();
+    const modifiers = this._modifiers._copy().orderByPriority();
     modifiers.validateModifiers('firebase.database().ref().orderByPriority()');
 
     return new DatabaseQuery(this._database, this.path, modifiers);
@@ -473,7 +481,7 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    const modifiers = this._modifiers.orderByValue();
+    const modifiers = this._modifiers._copy().orderByValue();
     modifiers.validateModifiers('firebase.database().ref().orderByValue()');
 
     return new DatabaseQuery(this._database, this.path, modifiers);
@@ -498,7 +506,7 @@ export default class DatabaseQuery extends ReferenceBase {
       );
     }
 
-    const modifiers = this._modifiers.startAt(value, key);
+    const modifiers = this._modifiers._copy().startAt(value, key);
     modifiers.validateModifiers('firebase.database().ref().startAt()');
 
     return new DatabaseQuery(this._database, this.path, modifiers);

packages/database/lib/DatabaseQueryModifiers.js

@@ -31,6 +31,16 @@ export default class DatabaseQueryModifiers {
     this._modifiers = [];
   }
 
+  _copy() {
+    const newInstance = new DatabaseQueryModifiers();
+    newInstance._limit = this._limit;
+    newInstance._orderBy = this._orderBy;
+    newInstance._startAt = this._startAt;
+    newInstance._endAt = this._endAt;
+    newInstance._modifiers = [...this._modifiers];
+    return newInstance;
+  }
+
   /**
    *
    * LIMIT