Merge

Author: schmidt-sebastian

src/document.js

@@ -1314,7 +1314,7 @@ class DocumentTransform {
           transforms.set(path, val);
         } else {
           throw new Error(
-            'Server timestamps are not supported as array values.'
+            'FieldValue transformations are not supported inside of array values.'
           );
         }
       } else if (is.array(val)) {

src/field-value.js

@@ -16,6 +16,18 @@
 
 'use strict';
 
+/*!
+ * Sentinel value for a field delete.
+ *
+ */
+let DELETE_SENTINEL;
+
+/*!
+ * Sentinel value for a server timestamp.
+ *
+ */
+let SERVER_TIMESTAMP_SENTINEL;
+
 /**
  * Sentinel values that can be used when writing documents with set() or
  * update().
@@ -45,7 +57,7 @@ class FieldValue {
    * });
    */
   static delete() {
-    return new DeleteTransform();
+    return DELETE_SENTINEL;
   }
 
   /**
@@ -66,7 +78,7 @@ class FieldValue {
    * });
    */
   static serverTimestamp() {
-    return new ServerTimestampTransform();
+    return SERVER_TIMESTAMP_SENTINEL;
   }
 
   /**
@@ -117,6 +129,8 @@ class DeleteTransform extends FieldTransform {
   }
 }
 
+DELETE_SENTINEL = new DeleteTransform();
+
 /**
  * A transform that sets a field to the Firestore server time.
  *
@@ -157,6 +171,8 @@ class ServerTimestampTransform extends FieldTransform {
   }
 }
 
+SERVER_TIMESTAMP_SENTINEL = new ServerTimestampTransform();
+
 module.exports = {
   FieldValue: FieldValue,
   FieldTransform: FieldTransform,

test/document.js

@@ -408,7 +408,7 @@ describe('serialize document', function() {
   });
 
   it("doesn't support server timestamp in array", function() {
-    const expectedErr = /Server timestamps are not supported as array values./;
+    const expectedErr = /FieldValue transformations are not supported inside of array values./;
 
     assert.throws(() => {
       return firestore.doc('collectionId/documentId').set({