Fix #dup() with relationships (#106)

This is a simpler implementation that doesn't blow up when the object
has relationships.

Author: richmolj

src/model.ts

@@ -653,11 +653,8 @@ export class JSORMBase {
   }
 
   dup(): this {
-    let nonEnums = getNonEnumerables(this)
-    flipEnumerable(this, nonEnums, true)
-    let cloned = cloneDeep(this)
-    flipEnumerable(this, nonEnums, false)
-    flipEnumerable(cloned, nonEnums, false)
+    let attrs = Object.assign({}, this.attributes, this.relationships)
+    let cloned = new this.klass(attrs) as any
     return cloned
   }
 

test/unit/model.test.ts

@@ -18,6 +18,7 @@ import {
 } from "../fixtures"
 
 import { Model, Attr, HasOne, HasMany, BelongsTo } from "../../src/decorators"
+import { eq } from 'lodash-es';
 
 // Accessing private property in unit tests so we need a type-loose conversion function
 const modelAttrs = (model: JSORMBase): Record<string, any> =>
@@ -1426,6 +1427,24 @@ describe("Model", () => {
       descriptor = Object.getOwnPropertyDescriptor(duped, 'relationships') as PropertyDescriptor
       expect(descriptor.enumerable).to.eq(false)
     })
+
+    // NB: does NOT dupe the relationships
+    describe("when nested relationships", () => {
+      it("still works", () => {
+        let author = new Author({ firstName: "Stephen" })
+        author.isPersisted = true
+        let genre = new Genre({ name: 'Horror' })
+        genre.isPersisted = true
+        let book1 = new Book({ genre })
+        book1.isPersisted = true
+        author.books = [book1]
+        let duped = author.dup()
+        expect(duped.books).to.deep.eq([book1])
+        expect(duped.books[0].isPersisted).to.eq(true)
+        expect(duped.books[0].genre).to.eq(genre)
+        expect(duped.books[0].genre.isPersisted).to.eq(true)
+      })
+    })
   })
 
   describe("#fetchOptions", () => {