Fix View sort does not support non-numerical prop

packages/datx/src/View.ts

@@ -51,7 +51,7 @@ export class View<T extends PureModel = PureModel> extends ToMany<T> {
           ? (item): any => item[this.sortMethod as 'string']
           : this.sortMethod;
 
-      list.sort((a: T, b: T) => sortFn(a) - sortFn(b));
+      list.sort((a: T, b: T) => (sortFn(a) === sortFn(b) ? 0 : sortFn(a) > sortFn(b) ? 1 : -1));
     }
 
     const instances = observable.array(list, { deep: false });

packages/datx/test/view.ts

@@ -123,6 +123,39 @@ describe('View', () => {
     expect(item2b && item2b.key).toBe(2);
   });
 
+  it('should be able to sort models by non-numerical prop', () => {
+    class Foo extends Model {
+      public static type = 'foo';
+
+      @Attribute()
+      public key!: string;
+    }
+    class AppCollection extends Collection {
+      public static types = [Foo];
+    }
+
+    const collection = new AppCollection();
+    const foos = collection.add([{ key: 'abd' }, { key: 'bbf' }, { key: 'ecf' }], Foo);
+    const viewInstance = new View(Foo, collection, (item: Foo) => item.key, foos);
+
+    expect(viewInstance).toHaveLength(3);
+    const item0a = viewInstance.list[0];
+    const item2a = viewInstance.list[2];
+
+    expect(item0a && item0a.key).toBe('abd');
+    expect(item2a && item2a.key).toBe('ecf');
+
+    const foo0 = collection.add({ key: 'ccc' }, Foo);
+
+    expect(viewInstance).toHaveLength(3);
+    viewInstance.add(foo0);
+    const item0b = viewInstance.list[0];
+    const item2b = viewInstance.list[2];
+
+    expect(item0b && item0b.key).toBe('abd');
+    expect(item2b && item2b.key).toBe('ccc');
+  });
+
   it('should be able to update sort method', () => {
     class Foo extends Model {
       public static type = 'foo';