Upgrade Guide from v3 to v4

Marionette 4 introduces a number of breaking changes. This upgrade guide will go through the major changes and describe how to change your application to accommodate them.

Required changes

These are breaking changes that need to be handled when migrating from Marionette v3 to v4

CompositeView was removed

• Old behavior: CompositeView class was provided
• New behavior: CompositeView does not exists
• Reason: API simplification
• Remedy: Use CollectionView instead. Most features of CompositeView were added to CollectionView and in common cases a class rename is enough. The old CompositeView was abstracted to a separate library.

One of the required changes is to explicitly define the childView when implementing a recursive (tree) view

   // with compositeview
   const TreeView = CompositeView.extend({
     template: 'node-template'
   })

   // with collectionview
   const TreeView = CollectionView.extend({
     template: 'node-template',
     childView () {
       return TreeView
     }
   })

NextCollectionView was renamed to CollectionView

• Old behavior: Both NextCollectionView and CollectionView were provided
• New behavior: Only CollectionView, based on NextCollectionView is provided. The old CollectionView implementation was removed
• Reason: API simplification
• Remedy: Use CollectionView instead. The old CollectionView was abstracted to a separate library.

childViewEventPrefix flag is set to false by default

• Old behavior: childViewEventPrefix flag was set to true
• New behavior: childViewEventPrefix flag was set to false
• Reason: Performance Improvement
• Remedy: It is recommended that child view events are proxied only when necessary. Rather than turning it on globally, set the childViewEventPrefix per view that needs it. Even better explictly define the proxies via childViewEvents and childViewTriggers.

Marionette global instance is not attached to Backbone global instance

• Old behavior: Marionette could be acessed using Backbone.Marionette
• New behavior: Marionette is not attached to Backbone global instance
• Reason: Support named exports
• Remedy: Import Marionette classes directly or use global Marionette instance (when using as a standalone script)

noConflict was removed

• Old behavior: noConflict allowed for multiple installs of Marionette to be installed
• New behavior: Marionette no longer handles conflicts internally.
• Reason: Isn't useful with ES6
• Remedy: Use package managers if multiple versions are needed.

AppRouter was removed

• Old behavior: Marionette included a router
• New behavior: Marionette no longer includes a router
• Reason: AppRouter was used by a minority of cases
• Remedy: Use any router including the extract AppRouter https://github.com/marionettejs/marionette.approuter

Renderer class was removed

• Old behavior: The default renderer could be changed by setting Renderer.render
• New behavior: Renderer does not exists
• Reason: API simplification
• Remedy: Use Marionette.setRenderer which accepts a function with same signature as expected by Renderer.render

TemplateCache render removed

• Old behavior: Rendered templates using the TemplateCache
• New behavior: Renders templates directly template(data);
• Reason: TemplateCache is only used by a minority of users.
• Remedy: If needed use https://github.com/marionettejs/marionette.templatecache

Behavior Lookup was removed

• Old behavior: View behaviors could optionally be looked up via the global lookup naming scheme.
• New behavior: Behavior definitions must be defined on the view.
• Reason: Simplify API and no global Marionette instance

• Remedy: Attach behaviors to view definitions. In v3

  const MyBehavior = Marionette.Behavior.extend({...});
  
  Marionette.Behaviors.behaviorsLookup = function() {
    return {
      FooBehavior: MyBehavior
    };
  };
  
  const V3View = Marionette.View.extend({
    behaviors: {
      FooBehavior: {}
    }
  });
  

  In v4

  const MyBehavior = Behavior.extend({...});
  
  const V3View = View.extend({
    behaviors: {
      FooBehavior: MyBehavior
    }
  });
  

attachElContent not called unless the View renderer returns a value

• Old behavior: attachElContent was always called
• New behavior: attachElContent not called if the render doesn't return a value.
• Reason: Useful for renderers that modify the content directly.
• Remedy: Return at least an empty string if you need to have attachElContent called

Support for vanilla Backbone.View has changed

• Old behavior: Backbone.View instances were supported as is
• New behavior: To support Backbone.View is necessary to apply Marionette.Events mixin
• Reason: Improve performance
• Remedy: If vanilla Backbone.View is not used there's no required change, otherwise, apply the Marionette.Events mixinto the prototype of the view class intended to be used withMarionette`. Example:

  // once, in the application start
  import _ from 'underscore';
  import {Events} from 'backbone.marionette';
  _.extend(Backbone.View.prototype, Events);
  

triggerMethodOn was removed

• Old behavior: This method was use to triggerMethod on an object that did not have the method
• New behavior: Objects that need this functionality should mixin Marionette.Events
• Reason: Improve performance
• Remedy: Same as supporting a vanilla Backbone.View mentioned above

Function isNodeAttached was removed

• Old behavior: Utility function isNodeAttached was provided
• New behavior: isNodeAttached does not exists
• Reason: API simplification
• Remedy: Use native code: document.documentElement.contains(el)

View's template: false now no-ops the render

• Old behavior: Template was not rendered, but render events were triggered
• New behavior: No render events will occur
• Reason: Prevents incorrect usage of render
• Remedy: template: false was often used to generate render events when no render was performed. Use other hooks or methods when no template will be rendered.

View.showChildView and Application.showView now return the shown view

• Old behavior: These methods returned the region
• New behavior: These methods now return the shown view
• Reason: More useful return
• Remedy: Use getRegion if the region is needed after this method

View data serialization no longer clones the data

• Old behavior: model attributes were always cloned prior to template rendering
• New behavior: model attributes are no longer cloned
• Reason: Improve performance
• Remedy: Unlikely to be an issue but if no templateContext is defined templates can modify the actual model data if not careful. Clone if necessary.

View render is no longer bound to the view

• Old behavior: view.render was bound to the view
• New behavior: view.render is no longer bound to the view
• Reason: Improve performance
• Remedy: In most all cases this won't matter but if you need to call the render function out of the context, use call or apply.

Region no longer supports the selector property

• Old behavior: The selector or el property could be used to set the region el.
• New behavior: The el property can be used to set the el.
• Reason: Simplify API
• Remedy: Rename any selector used with Region to el.

Region preventDestroy option was removed from show and empty

• Old behavior: Option could be used to prevent destroying a leaving view
• New behavior: Option is no longer available
• Reason: Simplify API
• Remedy: Use detachView first if you need to remove a shown view without destroying.

Internally _.bind was replaced with Function.prototype.bind

• Old behavior: _.bind was used
• New behavior: Function.prototype.bind is used
• Reason: Preparing for lodash 5
• Remedy: This may affect anyone hoping to squeeze < IE9 support out of Marionette.

Application, Behavior, and Region no longer extend MnObject

• Old behavior: These classes extended Mn.Object.
• New behavior: These classes no longer extend anything.
• Reason: Shallow inheritance
• Remedy: If modifying the Object prototype you may need to modify the others too.

destroy functions only proxy a single argument

• Old behavior: Any number of arguments passed to a destroy functions were passed along to events.
• New behavior: Only one argument is passed
• Reason: Performance Improvement
• Remedy: If you need to pass multiple pieces of data through destroy use an object.

defaults was removed from Behavior

• Old behavior: Both options and defaults defined on Behavior are default options.
• New behavior: Only options define the Behavior's default options
• Reason: Simplify API
• Remedy: Rename any use of defaults to options.

View definition options will not be passed to the view initialize.

• Old behavior: options defined on the view definition were merged into options and passed to the Backbone.View constructor
• New behavior: Only options passed in at construction will be passed to the Backbone.View constructor.
• Reason: Performance Improvement
• Remedy: Define any default Backbone.View options on the view instance directly instead of in a nested options on the definition.

Error utility was made private

• Old behavior: The Marionette.Error class was publicly available.
• New behavior: There is no accessible Error class.
• Reason: Simplify API and maintenance

DEV_MODE which shows deprecation warnings was made a feature flag.

• Old behavior: DEV_MODE was set on the global Marionette object.
• New behavior: Use setEnabled to set the DEV_MODE feature flag.
• Reason: There is no longer a global Marionette object.

Recommended changes (deprecations)

These changes are optional, although recommended to make future upgrades easy

The default export has been deprecated

• Old behavior: The package was exported as an UMD module with all classes / functions as a property of the default export
• New behavior: Package is exported as a ECMAScript module using named exports. The default export with all classes still
• Reason: Align with current JS standard practice, allow tree shaking

• Remedy: Import each Marionette classses / functions separatedly or with * keyword Examples: ```javascript // using ES module syntax // old behavior import Mn from 'backbone.marionette'; const MyView = Mn.View.extend({});

  // new behaviors // import only needed class/function import {View} from 'backbone.marionette'; const MyView = View.extend({});

  // or import all (kills any chance of tree shaking) import * as Mn from 'backbone.marionette'; const MyView = Mn.View.extend({});

  // or create a module that default exports all functions/classes // mymarionette.js -> can be configured as an alias for marionette or any other module name with webpack import * as Mn from 'backbone.marionette'; export default Mn;

  // myview.js import Mn from './mymarionette'; const MyView = Mn.View.extend({});

// using CommonJS syntax

// old behavior const Mn = require('backbone.marionette'); const MyView = Mn.View.extend({});

// new behavior const {View} = require('backbone.marionette'); const MyView = View.extend({});

#### `Marionette.Object` was renamed to `Marionette.MnObject`

 * **Old behavior:** The Marionette Object class was exported as `Marionette.Object`
 * **New behavior:** The Marionette Object class is exported as `MnObject`
 * **Reason:** Avoid collision with native `Object` class when using with ES imports
 * **Remedy:** Rename `Marionette.Object` to `MnObject`. To easy transition the Object will still be available on default Marionette export

```javascript
   // using ES module syntax
   // old behavior
   import Mn from 'backbone.marionette';
   const MyObj = Mn.Object.extend({});

   // new behaviors
   // import only needed class/function
   import {MnObject} from 'backbone.marionette';
   const MyView = MnObject.extend({});