We're developing a web service based on .NET webApi that will allow customers to create and update objects. When the model is handed to our controller, how do we differentiate between fields that are null/blank/0 because the caller wanted them set to null/blank/0, or fields that are null/blank/0 because that's the default used by parameter binding when the caller had no intentions of setting a value for that field? Is there a standard for dealing with this?
You should be able to just check the ModelState property on your controller. If a WebAPI action is invoked and the ModelState is valid, then it should mean that all the parameters were successfully bound from the URI or deserialized from the request body.
There's one caveat - this is only true for WebAPI's default parameter bindings. If you register your own custom parameter binding that binds the parameter differently, then all bets are off.
Now as far as properties and fields of parameters go, it's up to the formatter to decide how to handle those. Deserializers have two options when they encounter a member that's missing. They can either throw, or they can populate the member with 0/blank/null. You can ask the formatter to add a model state error when the property is missing by marking the property as [Required] or by using [DataMember(IsRequired=true)] if you're using the data contract model.
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I am trying to build a UI with left side bar having filters and right side having actual filtered data.
For loading data into the dynamic part of the UI(right side), which approach is considered better in terms of code quality and app performance ?
Use sub routes (for dynamic part of the UI)
Use separate components that load their own data (for dynamic part of
the UI)
There is not a direct correct answer for that; you can use both ways but here is a few things to consider and in the end I generally prefer to use sub-routes due to the following:
Waiting for UI to load: In case you are using separate components to load their own data; then you need to handle the loading state of the components. What I mean is; if you simply use sub-routes; then model hooks (model, beforeModel, etc.) will wait for the promises to be solved before displaying the data. If you simply provide a loading template (see the guide for details) it will be displayed by default. In case you use components, you might need to deal with displaying an overlay/spinner to give a better UX.
Error Handling: Similarly like loading state management; Ember has already built in support for error handling during route hook methods. You will need to deal with that on your own if you prefer components to make the remote calls. (See guide for details)
Application State: Ember is SPA framework; it is common practice to synchronize application state with the URL. If you use sub-routes; you can simply make use of the query parameters (see the guide for details) and you will be able to share the URL with others and the application will load with the same state. It is a little bit trickier to do the same with components; you still need to use query parameters within the routes and pass the parameters to the components to do that.
Use of component hook methods: If you intend to use the components then you will most likely need to use component hook methods to open the application with default filter values. This means you will need to make some remote call to the server within one or more of init, willRender, didReceiveAttrs component hook methods. I personally do not like remote calling within those methods; because I feel like this should better be done within routes and data should be passed to the components; but this is my personal taste of coding that you should approach the case differently and this is perfectly fine.
Data down, actions up keeps components flexible
In your specific example, I'll propose a third option: separate components that emit actions, have their data loaded by the route's controller, and never manipulate their passed parameters directly in alignment with DDAU.
I would have one component, search-filter searchParams=searchParams onFilterChange=(action 'filterChanged'), for the search filter and another component that is search-results data=searchResults to display the data.
Let's look at the search filter first. Using actions provides you with maximum flexibility since the search filter simply emits some sort of search object on change. Your controller action would look like:
actions: {
filterChanged(searchParams){
this.set('searchParams', searchParams);
//make the search and then update `searchResults`
}
}
which means your search-filter component would aggregate all of the search filter fields into a single search object that's used as the lone parameter of the onFilterChange.
You may think now, "well, why not just do the searching from within the component?" You can, but doing so in a DRY way would mean that on load, you first pass params to the component, a default search is made on didInsertElement which emits a result in an action, which updates the searchResults value. I find this control flow to not be the most obvious. Furthermore, you'd probably need to emit an onSearchError callback, and then potentially other actions / helper options if the act of searching / what search filter params can be applied together ever becomes conditionally dependent on the page in the app.
A component that takes in a search object and emits an action every time a search filter field changes is dead simple to reason about. Since the searchParams are one-way bound, any route that uses this component in it's template can control whether a field field updates (by optionally preventing the updating of searchParams in an invalid case) or whether the search ever fires based of validation rules that may differ between routes. Plus, theres no mocking of dependencies during unit testing.
Think twice before using subroutes
For the subroutes part of your question, I've found deeply nested routes to almost always be an antipattern. By deeply, I mean beyond app->first-child->second child where the first child is a sort of menu like structure that controls the changing between the different displays at the second child level by simple {{link-to}} helpers. If I have to share state between parents and children, I create a first-child-routes-shared-state service rather than doing the modelFor or controllerFor song and dance.
You must also consider when debating using children route vs handlebars {{if}} {{else}} sections whether the back button behavior should return to the previous step or return to the route before you entered the whole section. In a Wire transfer wizard that goes from create -> review -> complete, should I really be able to press the back button from complete to review after already having made the payment?
In the searchFilter + displayData case, they're always in the same route for me. If the search values need to be persistent on URL refresh, I opt for query params.
Lastly, note well that just because /users/:id/profile implies nesting, you can also just use this.route('user-profile', { 'path' : 'users/:id/profile' }) and avoid the nesting altogether.
I am new to ember and am trying to migrate an existing application, and would like to know what the recommendation is for modeling a single object that will be reused in multiple components on every page. ie: As part of the initial load, I would like to perform a GET request against a URL like 'https://example.com/currentUser' and get an object back like:
{
name: "Users Name"
email: "user#email.com",
profileImg: "http://example.com/pictureOfUser.png"
... snip ...
}
This object will then be used in components for menus, toolbars, and a form for updating it via a post to the same URL.
What is the best way to model this workflow in ember? Given that this is an incidental object and not the focus of most routes, it does not seem to make sense to specify it as the model of them. Also, does ember data handle cases where a model is a singleton and does not have an ID, or would I need to use something like Ember.$.ajax ?
What do you mean by "where a model is a singleton"?
If you use the ember-data default adapter, then yes, a model needs to have an ID, it's part of the JSONAPI spec. If you already have a backend with different conventions, take a look at extending or swapping out the default adapter.
A service is a singleton, and there is nothing preventing you from making an AJAX call there. You would be losing out on all the nice things that come along with ember-data, but, you can do it.
Currently I have a set up a application that lists the model collection and also have implemented pagination in it.
Now, I want to move all of this logic into a component so that it is reusable across multiple listings. To achieve this, I have passed the model variable inside the component.
Since, server data communication is considered a bad practice I assume the changes must be applied to the controller ?
So, I am confused on how to make the api call to refresh the data can be called ?
You can build method in controller and pass them as method in the required components. This way, you can avoid data call in component and make it reusable.
eg:
{{some-list getData=getSomeListData}}
where getSomeListData applies the required data changes.
Supposed I have a model containing 2 pre-populated fields. I would like to display these fields in the DOM for the user to modify if necessary. If I bind the DOM to the model using: {{input value=field1}} and {{input value=field2}}, then every time the user types in a character in one of these fields, Ember updates the bound model immediately. This is not the behavior I want. I prefer to show a button; when pressed, I want to validate data in the two fields in relation to each other, and if valid, update the model.
I considered creating mirrored fields in the controller and binding these to the DOM. Then create an action associated with the button to do the validation, and if data is found to be valid, copy data from the controller fields to the respective model fields. This technique may work, but seems like a very round-about way of doing something conceptually simple.
Do one of you Ember gurus out there have an opinion on how best to do this? I'm looking for best practices; please help.
I am not a guru nor am I familiar with client side validation in EmberData since our app uses server side validation.
Are you sure you can't allow your model to be updated immediately (i.e. bound to the template fields)?
If you did bind the model, then you could validate upon submission. If validation fails, you can just rollback the changes. If it passes, you can save the record. This is probably what I would do.
However, you clearly state that you do not want your model updated immediately, which means you don't want to bind your model.
Also, you have to do some processing that depends on multiple fields to validate, so it really sounds like binding to the controller and having a validation action is a good solution and that's what I would do if I wasn't binding to the model.
Playing around with ember, I found that sometimes the model is stored on the controller's content property, sometimes the model is directly available on the controller as well. I do not understand however, when this is the case.
Let me explain it by an example which I found when assembling my ember MVC.
Setup A - The start
I defined a custom Member object, corresponding MemberRoute, MemberView classes and a template with the name member.
The Member object had some attributes such as id, nickname, etc.
NOTE: no controller of the form MemberController was defined, thus by ember's convention, it provides the controller on its own.
Setup B - The customization
Same as setup A, but now there is a MemberController defined that contains some action methods that are triggered from within the template.
The strange behaviour (resp. what I do not completely understand)
in setup A, I can refer to the Member's attributes directly with {{id}} or {{nickname}}.
in setup B, I have to use {{content.id}} or {{content.nickname}}
As documented in ember's documentation, MemberView does
setupController : function(controller, member) {
controller.set('content', member);
},
So, could somebody help me to understand why the difference and where the difference is? Currently, my guess would be either
that the context of the template is different (possibly there is a code piece missing in the setup of the controller?)
or
the default controller that is provided by ember automatically, has some additional magic that is not directly avaiable for customized controllers.
Any help to understand this is highly appreciated. It already took my quite a while to come as far as this. I first thought it could be the modularization introduced by the project setup with requireJS (well, I still think that could have a influence). Ember is v1.0pre4.
Thanks in advance!
Patrick
So, could somebody help me to understand why the difference and where the difference is? Currently, my guess would be either
that the context of the template is different (possibly there is a code piece missing in the setup of the controller?)
or
the default controller that is provided by ember automatically, has some additional magic that is not directly avaiable for customized controllers.
It's hard to say for sure without seeing your code, but my best guess is that your MemberController extends Ember.Controller. The default provided by ember (in this scenario) would have been an Ember.ObjectController. If that's what you want, change your MemberController definition to:
App.MemberController = Ember.ObjectController.extend({
myProperty: 'value'
});
An objectController acts as a proxy to it's content property, typically that is an ember model. So if things are wired up correctly you should never need to access a model via the 'content` property. If you ever see something like:
{{content.id}} or {{content.nickname}}
it's a sign that you should change to an ObjectController. See EMBER GUIDES: REPRESENTING A SINGLE MODEL! for a more detailed explanation.
an ObjectController acts as proxy to the object set to the controller's content. When no controller is defined, Ember will create a controller for you and set its content by default to whatever object is returned by the model() function, if defined, in the route. The behaviour should be the same whether you define your own controller or let Ember define one for you
The default context in the template is the controller itself i.e. this = an instance of your controller or the generated one. When you try to access nickname in that context, Ember will first try to resolve it against the controller itself and if nothing is found, it resolves it against its content, i.e the object if you already manually set it to the controller's content.
Finally, there is no default implementation of the model() function in the Route except when you're using dynamic urls, say /foo/id that resolves against /foo/:id, Ember uses the id provided to load a Foo object with the id provided, thus providing a default implementation to the model() function. At the end it boils down to the same mechanism, only automated for your convenience.
I suggest you listen to this for more insights on how things are automated for you by Ember. But when it comes to the content being displayed, there is no magic you have to manually wire the content of the controller.