From 165fe03352c93e0a4f895ba1c9ecf07683c91887 Mon Sep 17 00:00:00 2001
From: Tony Sun <tony.sun427@gmail.com>
Date: Tue, 3 Oct 2017 17:40:24 -0700
Subject: fix exists false when field is explicitly defined

When users explicitly defined a text index's fields, and used $exists
with false, we tag false when constructing the query. This led to a
function clause for indexable_fields since we did not account for it.
This fix patches that up, but note that we don't care about the false
value itself since we only care about fields.
---
 src/mango/src/mango_idx_text.erl                 |  3 ++
 src/mango/test/07-text-custom-field-list-test.py | 50 ++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/src/mango/src/mango_idx_text.erl b/src/mango/src/mango_idx_text.erl
index 1d5ae9bad..369e2cd08 100644
--- a/src/mango/src/mango_idx_text.erl
+++ b/src/mango/src/mango_idx_text.erl
@@ -329,6 +329,9 @@ indexable_fields(Fields, {op_or, Args}) when is_list(Args) ->
 indexable_fields(Fields, {op_not, {ExistsQuery, Arg}}) when is_tuple(Arg) ->
     Fields0 = indexable_fields(Fields, ExistsQuery),
     indexable_fields(Fields0, Arg);
+% forces "$exists" : false to use _all_docs
+indexable_fields(Fields, {op_not, {ExistsQuery, false}}) ->
+    [];
 
 indexable_fields(Fields, {op_insert, Arg}) when is_binary(Arg) ->
     Fields;
diff --git a/src/mango/test/07-text-custom-field-list-test.py b/src/mango/test/07-text-custom-field-list-test.py
index a43e33003..9bfe07598 100644
--- a/src/mango/test/07-text-custom-field-list-test.py
+++ b/src/mango/test/07-text-custom-field-list-test.py
@@ -12,6 +12,7 @@
 
 import mango
 import unittest
+import user_docs
 
 
 @unittest.skipUnless(mango.has_text_service(), "requires text service")
@@ -160,3 +161,52 @@ class CustomFieldsTest(mango.UserDocsTextTests):
         })
         assert len(docs) == 1
         assert docs[0]["user_id"] == 10
+
+@unittest.skipUnless(mango.has_text_service(), "requires text service")
+class CustomFieldsExistsTest(mango.UserDocsTextTests):
+
+    FIELDS = [
+        {"name": "exists_field", "type": "string"},
+        {"name": "exists_array.[]", "type": "string"},
+        {"name": "exists_object.should", "type": "string"},
+        {"name": "twitter", "type": "string"}
+    ]
+
+    def test_exists_field(self):
+        docs = self.db.find({"exists_field": {"$exists": True}})
+        self.assertEqual(len(docs), 2)
+        for d in docs:
+            self.assertIn(d["user_id"], (7, 8))
+
+        docs = self.db.find({"exists_field": {"$exists": False}})
+        self.assertEqual(len(docs), len(user_docs.DOCS) - 2)
+        for d in docs:
+            self.assertNotIn(d["user_id"], (7, 8))
+
+    def test_exists_array(self):
+        docs = self.db.find({"exists_array": {"$exists": True}})
+        self.assertEqual(len(docs), 2)
+        for d in docs:
+            self.assertIn(d["user_id"], (9, 10))
+
+        docs = self.db.find({"exists_array": {"$exists": False}})
+        self.assertEqual(len(docs), len(user_docs.DOCS) - 2)
+        for d in docs:
+            self.assertNotIn(d["user_id"], (9, 10))
+
+    def test_exists_object_member(self):
+        docs = self.db.find({"exists_object.should": {"$exists": True}})
+        self.assertEqual(len(docs), 1)
+        self.assertEqual(docs[0]["user_id"], 11)
+
+        docs = self.db.find({"exists_object.should": {"$exists": False}})
+        self.assertEqual(len(docs), len(user_docs.DOCS) - 1)
+        for d in docs:
+            self.assertNotEqual(d["user_id"], 11)
+
+    def test_exists_false_same_as_views(self):
+        docs = self.db.find({
+                "twitter": {"$exists": False}
+            })
+        for d in docs:
+            self.assertNotIn(d["user_id"], (0, 1, 4, 13))
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