From 68f82c22eeb755cd6f72e3f2fdb7815a58b26570 Mon Sep 17 00:00:00 2001
From: Nathan Knight <knathanknight@gmail.com>
Date: Fri, 2 Jun 2023 16:48:40 -0400
Subject: [PATCH] fix: correctly get schema for each element of a discriminated
 array and do not attempt to get the schema for null/undefined docs

---
 index.js           | 11 +++++++----
 test/index.test.js | 28 ++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/index.js b/index.js
index 92bb6d0..4cf281a 100644
--- a/index.js
+++ b/index.js
@@ -67,7 +67,7 @@ function applyGetters(schema, res, path) {
 }
 
 function getSchemaForDoc(schema, res) {
-  if (!schema.discriminatorMapping || !schema.discriminatorMapping.key) {
+  if (!schema.discriminatorMapping || !schema.discriminatorMapping.key || !schema.discriminators) {
     return schema;
   }
 
@@ -81,15 +81,18 @@ function applyGettersToDoc(schema, doc, fields, prefix) {
     return;
   }
 
-  const schemaForDoc = getSchemaForDoc(schema, doc);
-
   if (Array.isArray(doc)) {
     for (let i = 0; i < doc.length; ++i) {
-      applyGettersToDoc.call(this, schemaForDoc, doc[i], fields, prefix);
+      const currentDoc = doc[i];
+      if (currentDoc == null) continue;
+      const schemaForDoc = getSchemaForDoc(schema, currentDoc);
+      applyGettersToDoc.call(this, schemaForDoc, currentDoc, fields, prefix);
     }
     return;
   }
 
+  const schemaForDoc = getSchemaForDoc(schema, doc);
+
   schemaForDoc.eachPath((path, schematype) => {
     const pathWithPrefix = prefix ? prefix + '.' + path : path;
     if (this.selectedInclusively() &&
diff --git a/test/index.test.js b/test/index.test.js
index 6d0f2ed..bca210f 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -249,4 +249,32 @@ describe('mongoose-lean-getters', function() {
 
     assert.equal(docs[0].url, 'https://www.test.com discriminator field');
   });
+
+  it('should work on schemas with discriminators in arrays', async function() {
+    const options = { discriminatorKey: 'kind' };
+
+    const eventSchema = new mongoose.Schema({ time: Date }, options);
+    const clickedLinkSchema = new mongoose.Schema({
+      url: { type: String, get: v => v + ' discriminator field' }
+    });
+    eventSchema.discriminator('ClickedLink', clickedLinkSchema);
+
+    const eventListSchema = new mongoose.Schema({
+      events: [eventSchema],
+    });
+    eventListSchema.plugin(mongooseLeanGetters);
+    const EventList = mongoose.model('EventList', eventListSchema);
+
+    await EventList.deleteMany({});
+    await EventList.create({
+      events: [{
+        kind: 'ClickedLink',
+        url: 'https://www.test.com'
+      }],
+    });
+
+    const docs = await EventList.find().lean({ getters: true });
+
+    assert.equal(docs[0].events[0].url, 'https://www.test.com discriminator field');
+  });
 });