From 93b95c21d1298c3cbb1440bff20f6e9b63192546 Mon Sep 17 00:00:00 2001
From: Sunny Patel <sunny.patel@xome.com>
Date: Thu, 21 Jun 2018 09:44:48 -0500
Subject: [PATCH] Allow Query Filter values of null, undefined, or NaN to
 coalesce into a Unary Filter.

---
 Query.js | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/Query.js b/Query.js
index fe745a0..d38daad 100644
--- a/Query.js
+++ b/Query.js
@@ -46,11 +46,17 @@ var FirestoreQuery_ = function (from, callback) {
   const filter = function (field, operator, value) {
     // @see {@link https://firebase.google.com/docs/firestore/reference/rest/v1beta1/StructuredQuery#FieldFilter Field Filter}
     if (operator in fieldOps) {
-      return {
-        fieldFilter: {
-          field: fieldRef(field),
-          op: fieldOps[operator],
-          value: wrapValue_(value)
+      if (value == null) { // Covers null and undefined values
+        operator = 'null'
+      } else if (isNaN(value)) { // Covers NaN
+        operator = 'nan'
+      } else {
+        return {
+          fieldFilter: {
+            field: fieldRef(field),
+            op: fieldOps[operator],
+            value: wrapValue_(value)
+          }
         }
       }
     }