added note about update query

2 files changed, 20 insertions, 4 deletions

diff --git a/README.md b/README.md
index 03b98e6..c1c8d1b 100644
--- a/README.md
+++ b/README.md
@@ -46,12 +46,28 @@ const myCoolPost = {
 //  it with your user ID and a random
 //  object ID, required by the server)
 gs.complete(myCoolPost)
-await gs.update(myCoolPost)
+await gs.update(myCoolPost, {})
 
 // replace objects,
 myCoolPost.content += '!!!'
-await gs.update(myCoolPost)
+await gs.update(myCoolPost, {})
 
 // and remove objects.
 await gs.remove(myCoolPost)
+
+// The second argument in the update
+// function is a query. If the object you
+// try to add does not match the query
+// it will be rejected. This prevents
+// you from accidentally creating data
+// that gets "lost".
+const query = { type: 'post' }
+const myPost = { type: 'post' }
+const myNotPost = { type: 'notpost' }
+gs.complete(myNotPost)
+// This works
+await gs.update(myPost, query)
+// But this won't work!
+await gs.update(myNotPost, query)
+
 ```
diff --git a/src/socket.js b/src/socket.js
index 5c7760c..be17304 100644
--- a/src/socket.js
+++ b/src/socket.js
@@ -121,10 +121,10 @@ export default class {
     }
   }
 
-  async update(object) {
+  async update(object, query) {
     const data = await this.request({
       type: "update",
-      object
+      object, query
     })
     return data.objectID
   }