PG: Fix containedIn query on empty array (parse-community#5254)

* PG: Fix containedIn query on empty array

* improve logic

Author: dplewis

spec/ParseQuery.spec.js

@@ -238,6 +238,30 @@ describe('Parse.Query testing', () => {
       });
   });
 
+  it('query notContainedIn on empty array', async () => {
+    const object = new TestObject();
+    object.set('value', 100);
+    await object.save();
+
+    const query = new Parse.Query(TestObject);
+    query.notContainedIn('value', []);
+
+    const results = await query.find();
+    equal(results.length, 1);
+  });
+
+  it('query containedIn on empty array', async () => {
+    const object = new TestObject();
+    object.set('value', 100);
+    await object.save();
+
+    const query = new Parse.Query(TestObject);
+    query.containedIn('value', []);
+
+    const results = await query.find();
+    equal(results.length, 0);
+  });
+
   it('query with limit', function(done) {
     const baz = new TestObject({ foo: 'baz' });
     const qux = new TestObject({ foo: 'qux' });

src/Adapters/Storage/Postgres/PostgresStorageAdapter.js

@@ -402,8 +402,8 @@ const buildWhereClause = ({ schema, query, index }): WhereClause => {
       index = index + 1 + inPatterns.length;
     } else if (isInOrNin) {
       var createConstraint = (baseArray, notIn) => {
+        const not = notIn ? ' NOT ' : '';
         if (baseArray.length > 0) {
-          const not = notIn ? ' NOT ' : '';
           if (isArrayField) {
             patterns.push(
               `${not} array_contains($${index}:name, $${index + 1})`
@@ -430,6 +430,13 @@ const buildWhereClause = ({ schema, query, index }): WhereClause => {
           values.push(fieldName);
           patterns.push(`$${index}:name IS NULL`);
           index = index + 1;
+        } else {
+          // Handle empty array
+          if (notIn) {
+            patterns.push('1 = 1'); // Return all values
+          } else {
+            patterns.push('1 = 2'); // Return no values
+          }
         }
       };
       if (fieldValue.$in) {