From 838423125180d80f10a75b07b601c9dd284405e7 Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Fri, 22 Feb 2019 13:26:32 -0500
Subject: [PATCH] fix(schema): ensure clone() correctly gets `childSchemas`

Re: #7537
---
 lib/schema.js                    | 20 +++++++++++++++++++-
 test/model.discriminator.test.js |  1 -
 test/schema.test.js              | 14 ++++++++++++++
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/lib/schema.js b/lib/schema.js
index e500ca06ac7..361a01e0f46 100644
--- a/lib/schema.js
+++ b/lib/schema.js
@@ -301,12 +301,13 @@ Schema.prototype.clone = function() {
   s.paths = utils.clone(this.paths);
   s.nested = utils.clone(this.nested);
   s.subpaths = utils.clone(this.subpaths);
-  s.childSchemas = this.childSchemas.slice();
   s.singleNestedPaths = utils.clone(this.singleNestedPaths);
+  s.childSchemas = gatherChildShemas(s);
 
   s.virtuals = utils.clone(this.virtuals);
   s.$globalPluginsApplied = this.$globalPluginsApplied;
   s.$isRootDiscriminator = this.$isRootDiscriminator;
+  s.$implicitlyCreated = this.$implicitlyCreated;
 
   if (this.discriminatorMapping != null) {
     s.discriminatorMapping = Object.assign({}, this.discriminatorMapping);
@@ -622,6 +623,23 @@ Schema.prototype.path = function(path, obj) {
   return this;
 };
 
+/*!
+ * ignore
+ */
+
+function gatherChildShemas(schema) {
+  const childSchemas = [];
+
+  for (const path of Object.keys(schema.paths)) {
+    const schematype = schema.paths[path];
+    if (schematype.$isMongooseDocumentArray || schematype.$isSingleNested) {
+      childSchemas.push({ schema: schematype.schema, model: schematype.caster });
+    }
+  }
+
+  return childSchemas;
+}
+
 /**
  * The Mongoose instance this schema is associated with
  *
diff --git a/test/model.discriminator.test.js b/test/model.discriminator.test.js
index 5579ed8f133..6bf99dbee01 100644
--- a/test/model.discriminator.test.js
+++ b/test/model.discriminator.test.js
@@ -501,7 +501,6 @@ describe('model', function() {
       });
 
       it('supports clone() (gh-4983)', function(done) {
-        console.log('-----------');
         var childSchema = new Schema({
           name: String
         });
diff --git a/test/schema.test.js b/test/schema.test.js
index a909a60bdcd..04ba2b9158a 100644
--- a/test/schema.test.js
+++ b/test/schema.test.js
@@ -1876,6 +1876,20 @@ describe('schema', function() {
         assert.equal(otherSchema.path('name').validators.length, 1);
         assert.equal(schema.path('name').validators.length, 0);
       });
+
+      it('correctly copies all child schemas (gh-7537)', function() {
+        const l3Schema = new Schema({ name: String });
+        const l2Schema = new Schema({ l3: l3Schema });
+        const l1Schema = new Schema({ l2: l2Schema });
+
+        assert.equal(l1Schema.childSchemas.length, 1);
+        assert.ok(l1Schema.childSchemas[0].schema.path('l3'));
+
+        const otherSchema = l1Schema.clone();
+
+        assert.equal(otherSchema.childSchemas.length, 1);
+        assert.ok(otherSchema.childSchemas[0].schema.path('l3'));
+      });
     });
 
     it('TTL index with timestamps (gh-5656)', function(done) {