Let's say we are implementing CRUD operations for a specific object - those view would be very similiar and i think i should use the same view with multiple controllers. Is there a way to choose the controller dinamicaly based on a parameter or this type of action can be only taken inside the controller?
You technically can, but according to the exellent angular styleguide from Johnpapa, style Y037 :
Define a controller for a view, and try not to reuse the controller
for other views.
Though, you're actually right thinking that some CRUD logic should be made common and abstracted. Controllers are just not the right place; Factories (ie services) are.
You can use the same view on different controllers but it depends on what you are doing inside the view and whether or not the controller has the necessary members within the $scope object that are bound in the view. You can add an "action" variable on your $scope object and modify the view based on the same.
When using {{render "modelHandler" model}} the corresponding controller's model function is never called.
Reproduced here: http://jsbin.com/EVoXAceP/3/edit
I'm 90% sure this is a bug. I'm posting this here before I post to github in case there is something obvious I've missed or "I'm doing it wrong." In either case, if you could kindly point me in the right direction.
Use Case (Why I need this to work in the first place).
I'm using {{render}} to include an AddressAdd template, for which I need to extend the model to include a list of states as well as the default state. While I could load the states onto the parent model (say a property or a contact card), since many views include an AddressAdd I'd like to avoid having to manually add the information for the drop down each time.
So if you also happen to know a better way of implementing this besides {{render}} and the controller's model hook, please let me know!
It isn't a bug, the model hook is only fired when you visit the url associated with that route, and it lives on the route, not on a controller. Additionally, if your controller has a model on it it should be an ObjectController (unless it's an array, then it's an ArrayController).
http://jsbin.com/EVoXAceP/13/edit
When you call render you are saying you want to render a particular template using a particular context.
I would create a route underneath the route you're in and use a link-to without a model, which will cause the model hook to fire.
In your application template
{{ render 'foo' bar }}
shouldn't you have a bar property in the ApplicationController?
App.ApplicationController = Ember.Controller.extend({
bar: {isBar: 'yup'}
});
Does anyone know what's the easiest way to get an instance of a view model within another view model. To be more specific, i would like to load the instance of one view model into another view model so that the latter can call methods of the former.
Does durandal keep a list of all view models that were used during the composition?
I guess one way to deal with that is applying the pub/sub pattern which is supported by durandal.
Another way would probably be to manually get the view model with the aid of knockout and the dataFor utility function.
However, i would like to know if there is a way to explicitly get the instance of a composed view model.
Note: my modules expose a constructor rather that singleton object
You can do it just by using RequireJS to bring in the viewmodel like you would another module/viewmodel. But you really want to avoid this for viewmodel communication and go with events instead.
A viewmodel will publish an event through the event aggregator and the other viewmodel is then subscribing to that event.
Check out the “Using Application-Wide Messaging” section here.
I'm looking through examples on the AngularJS home page — specifically “Add Some Control”. I don’t quite understand how it maps to MVC pattern.
It’s more or less clear that the template (index.html) can be thought of as the view, objects constructed by TodoCtrl from todo.js as the controller, but where is a model? Attributes like ng-model map to some internal pieces of the framework and don’t directly expose an object which we could call a model.
Is it correct to call AngularJS an MVC framework?
The core idea behind MVC is that you have clear separation in your code between
managing its data (model), the application logic (controller), and presenting the data
to the user (view).
The view gets data from the model to display to the user. When a user interacts with the
application by clicking or typing, the controller responds by changing data in the model.
Finally, the model notifies the view that a change has occurred so that it can update what
it displays.
In Angular applications, the view is the Document Object Model (DOM), the controllers
are JavaScript classes, and the model data is stored in object properties.
I havent read up on Angular. However, keep in mind that "true" MVC means that the Model contains business Logic, the Controller takes care of communicating user input to the Model, and the View gets its own data from the Model. Many so called MVC frameworks are actually not implementing MVC the right way: They are overloading the Controller With to much responsibility, as in making the Controller responsible also to update the View. That is not what the Controller was intended to do, and in such cases you get what is called a "fat Controller". There is a misconseption among many webdevelopers that the View is simply a "template". This is both true and false; It is a template but it get its own data directly from the Model - not via the Controller.
But as I started out saying: I havent yet read up on Angular, but you might have so yourself and you should be able to find out if Angular is truly a MVC framework by looking at what the different Components in the Framework does.
The attributes map into the scope variable as defined in the controller. For example, if you have some JS objects which represent your business logic, you can put those in the scope variable, and then the attributes can be mapped into the model itself instead of some arbitrary values in the scope variable.
If anything that can store data in a object is considered a model than every front end framework (view) could be considered to have a model. They can all store data in objects and present them in the view. I think calling angular a mvc is really a marketing ploy, trying to make angular seem like it is more than it is.
See:
https://www.pluralsight.com/blog/software-development/tutorial-angularjs-mvc-implementation
In the controller, is where they give their example of angular's as a model. If it can't assist in the storage of persistent data it isn't much of a model.
I'm building my first Backbone.js app and I'm confused about how much responsibility I'm supposed to give to or hide from my Views.
In my example, I'm building a Rich UI Table (similar to YUI's datagrid) that's dynamically generated from a Collection. In my app I call this an "AppTable". In my understanding of MVC, I would imagine that there'd be some kind of AppTable controller which finds the correct Collection, grabs a "dumb" View and passes to the View whatever information from the Collection it needs to render. In this senario, the View would do little more than take the data provided to it and modify the DOM accordingly, maybe even populating a template or attaching event listeners.
Backbone seems to do away with the idea of having a controller mediate between the View and Collection. Instead a View gets initialized with a reference to a Collection and it is View's responsibility to update itself.
Am I understanding this architecture correctly?
Assuming I do, my question then becomes, what happens when my View needs to do more and more? For example, I want column sorting, drag-and-drop for rows, pagination, searching, table control links (like new, copy, delete row... etc), and more. If we stick with a "smart" View paradigm where the View is connected directly to a Collection, do the above functions become attached to View object?
Thinking through this, I could see the View growing from a simple table wrapper to pretty messy beast with lot of functionality attached to it. So, is the View really a controller in this case?
Your understanding of the architecture is correct. Backbone does not recognize the concept of a "controller" in the traditional MVC sense. (In fact, Backbone used to actually have an object called a Controller, but it has been renamed Router to more accurately describe what it does.)
The functions you list (drag-drop, delete rows, sorting, etc.) would all belong in a View. A view describes what you see and responds to user input. Anything involving an event (a click, a keypress, a submit, etc.) all go inside of a view. But your view should never actually manipulate the data; that should be done by its model. You are correct in thinking that a view acts like a controller, because it packages data and sends it to the model, which will then validate/set/save appropriately. Once those actions have occurred, the view re-renders itself to represent the new version of the data inside the model.
One note of caution: your view should not be too strenuously tied to the DOM. It is Backbone convention to have a top-level DOM element that your view is tied to (e.g., a form or a div) and then deal only with its sub-elements. That is appropriate; in general, things like "remove this link from this div" inside your view are not. If you find your view growing unwieldy, you most likely need to break it into subviews, each with their respective behaviors as components of their whole.
My thoughts on this updated below:
I think Josh gave a good answer, however, in my experience, building a few Backbone apps, even medium-complexity apps do need a separate controller class.
To clarify what I mean about a controller: The functionality between the model (or router) and the view that creates and instantiates the new view class and kills (and unregisters events) on the old one. This functionality might be the same for many views (so a direct one-to-one relationship between views and controllers probably isn't needed) but sometimes one needs to pass in a model or other additional extra values.
Right now, I just have one controller with a few if statements for adding some unique data to certain views for most apps I've built but I'm looking at setting up an architecture where it will check to see if a unique controller exists for that view else it falls back to the standard controller. Nothing special, but should do the job.
Update: After six months of building Backbone apps I realized that routers can be split up and extended just like views. (duh?)
Right off the bat, I knew to make a base view of functionality I know that all my views would need. Similarly, I would make base views for each section, like "profile" pages or "inbox" pages that I know would all use the same functionality. This wasn't so clear to me in the beginning with routers, but the previous name of "Controller" hinted at this.
Most people (as in every example of Backbone I've ever seen on the web) just use one monolithic router instantiation to handle all routes but you can actually have 1-to-1 parity of routers to views, or in my case, a base router for checking user auth and such and then one for each major section. That way if you need to pass in certain models or collections to a router on page load, you don't need to add code to one monolithic router, but instead pull up the unique router for that view. I find this is currently better than creating a separate controller class. The base router can be in charge of last instantiated view, etc, so you can kill the last view before instantiating the new one.
TLDR: Use multiple Routers as controllers. I believe that's what they were meant for and it works well.
I've struggled with the same semantic issues when trying to map out a single-page app. In the end I decided that Backbone is using the wrong name.
When you look at a Backbone app in the browser, the View is not actually a view at all, its el member is the view. Backbone.View is either a view controller or, probably more correctly, a presenter.
Some supporting evidence:
you never see a Backbone.View on the screen, its always the el or $el that is applied to the DOM
a Backbone.View does not receive user input, the DOM element receives input and the events are delegated via the events hash of the "view"
a BackBone.View manages model or collection changes and translates these changes to dumb-view (DOM) elements, then applies them to the actual view, e.g. this.$el.append('<p>Cats!')
I think Backbone.Presenter would be a better name, but I can also see the historical issues with there being a former Backbone.Controller and the amount of work renaming introduces.
I have settled on the following structure for my latest project:
an app controller, extended from Backbone.View, tied to the body element
several model collections to cache data retrieved from the server
a Backbone.Router that translates route changes into Backbone events and triggers them on itself
many app controller methods that handle the router events the app controller listens to
an app controller method prepares any needed models, then initiates a presenter (extended from Backbone.View) and attaches it to the body element
All these parts are initiated and owned by the app controller. The presenters do not know why or where they are on the page and only care for their own DOM elements and the changes they receive from this.model.
Have a look at this part of backbone documentation
http://documentcloud.github.com/backbone/#FAQ-tim-toady
References between Models and Views can be handled several ways. Some
people like to have direct pointers, where views correspond 1:1 with
models (model.view and view.model). Others prefer to have intermediate
"controller" objects that orchestrate the creation and organization of
views into a hierarchy. Others still prefer the evented approach, and
always fire events instead of calling methods directly. All of these
styles work well.
So, backbone does not take that decision for you.
I have a very similar use case (table grid with pagination, ordering, live filtering, and forms with client-side validation, master-details relations, etc.)
In my case, I first started with a Router behaving just like a controller, and quite quickly my code got a bit messy.
So I completely removed Routers (I'll add them back later, but just as an addition) and created my own controller (that in fact works as a presenter). It's just a javascript class, with Backbone.extend backed in to handle inheritance.
The idea is that the view recieves all the data it needs to display itself (model, collection, and the el in which it should be parsed), set up listener on dom events, and then executes controller methods. It never directly modifies the data nor it interacts with other views, it tells the controller to do it.
A view can have subviews, and in that case the subview only interacts with the parent view, or directly with the controller.
So far now it seems to work, but anyway things are not so simple as I expected them to be...
I hope to publish it in the next few days.
A different perspective from the other answers here is that, just because you are using the Backbone framework, that doesn't mean that your entire codebase must be wrapped in Backbone classes.
Personally, my controller is an amalgamation of "raw" Javascript and Backbone routes, and I never use Views for control logic at all. IMHO views are for ... well, view logic, and specifically for wrapping elements. If you're using a view for anything that doesn't directly connect to an HTML element you are (again, IMHO) doing something wrong.
Backbone is awesome, but that doesn't mean that it's a silver bullet that can be applied to everything.