Better error handling

.gitignore

@@ -4,4 +4,6 @@ node_modules/*
 npm-debug.log
 
 .nyc_output
-coverage
+coverage
+
+.vscode

dist/Model.js

@@ -480,6 +480,13 @@ var Model = /** @class */ (function () {
      */
     Model.prototype.__setRef = function (ref, val) {
         var _this = this;
+        var isArray = val instanceof Array || mobx_1.isObservableArray(val);
+        var hasModelInstances = isArray
+            ? val.some(function (item) { return item instanceof Model; })
+            : val instanceof Model;
+        if (!this.__collection && hasModelInstances) {
+            throw new Error('Model needs to be in a collection to set a reference');
+        }
         var type = this.__refs[ref];
         var refs = utils_1.mapItems(val, this.__getValueRefs.bind(this, type));
         var getRef = function () { return _this.__collection ? (_this.__getReferencedModels(ref) || undefined) : undefined; };

src/Model.ts

@@ -595,6 +595,14 @@ export class Model implements IModel {
    * @memberOf Model
    */
   private __setRef<T>(ref: string, val: T|Array<T>): IModel|Array<IModel> {
+    const isArray = val instanceof Array || isObservableArray(val);
+    const hasModelInstances = isArray
+      ? (val as Array<T>).some((item) => item instanceof Model)
+      : val instanceof Model;
+
+    if (!this.__collection && hasModelInstances) {
+      throw new Error('Model needs to be in a collection to set a reference');
+    }
     const type = this.__refs[ref];
     const refs = mapItems<number|string>(val, this.__getValueRefs.bind(this, type));
 

test/main.ts

@@ -1615,4 +1615,29 @@ describe('MobX Collection Store', () => {
       expect(foo.bar[2].id).to.equal(5);
     });
   });
+
+  describe('Error handling', () => {
+    it('Should throw when setting references on a model not in a collection', () => {
+      class FooModel extends Model {
+        public static type = 'foo';
+        public static refs = {bar: 'bar'};
+
+        public id: number|string;
+        public bar: BarModel;
+      }
+
+      class BarModel extends Model {
+        public static type = 'bar';
+
+        public id: number|string;
+      }
+
+      const bar = new BarModel({id: 1});
+
+      const foo1 = new FooModel({id: 1});
+      expect(foo1).to.be.an('object');
+
+      expect(() => new FooModel({id: 2, bar})).to.throw(Error, 'Model needs to be in a collection to set a reference');
+    });
+  });
 });