Note: The English used in this article (along with the terms) may be a bit "out of order" since my native language is not English. Rest assured I have tried my best to make it as readable as possible, and if I have missed anything please do comment before downvoting so I may update the question accordingly (I'm still new to this)
So I've searched most of the internet for a solution to this, to find a tutorial that would guide me on the metadata driven approach for building an application on EmberJS. The documentation on Ember doesn't explain anything about the approach, just a function definition of extractMeta here, and a basic overview of how to handle metadata here.
What I want to achieve is to build a portal, with Sugar as the back-end for the application. The application will use REST API for making calls to extract the data as well as the metadata of the application. We want to make the application generic, so that no matter what module is called, the metadata is extracted to determine the fields required in the model, a filtered portion of the data needed from the call is populated into the model accordingly and the is displayed in a generic template, that will be global and used throughout the application.
The metadata includes various items such as buttons, panels, attributes(each with multiple layers of data within) etc, each may be used once or multiple times within the call or not at all. For example, for displaying the application would require the attributes for display within the table, as well as buttons for adding, deleting updating etc. Upon click the panel may be required for say, adding a particular record, which itself may contain various fields.
As an example, is the default Sugar instance that shows the leads in the data, notice how it contains various components.
Here, another example, of the panel that appears when I click the create button in the leads list, notice the fields that appear within the panel
Please Note that I do understand how to make the REST API calls for the data as well as the metadata. But how to turn that into a generic meta driven application is what I am struggling with. Thanks in advance!
If I understand this correctly, you're looking for some kind of generic UI builder based off of returned data from a REST endpoint. Ember provides the component helper.
The {{component}} helper can be used to defer the selection of a
component to run time. The {{my-component}} syntax always renders the
same component, while using the {{component}} helper allows choosing a
component to render on the fly. This is useful in cases where you want
to interact with different external libraries depending on the data.
Using the {{component}} helper would allow you to keep different logic
well separated.
{{#each model as |post|}}
{{!-- either foo-component or bar-component --}}
{{component post.componentName post=post}}
{{/each}}
Read here for a more thorough explanation.
What you essentially need to do is build a bunch of different components for each of the possible attributes from the metadata. Your models will contain what components they should render and you'll use the component helper to dynamically render the correct elements.
If you're using a table based approach, have a look at ember light table. They leverage this approach heavily with how they build the columns for their tables and support custom components:
columns: computed(function() {
return [{
label: 'Avatar',
valuePath: 'avatar',
width: '60px',
sortable: false,
cellComponent: 'user-avatar'
}, {
label: 'First Name',
valuePath: 'firstName',
width: '150px'
}];
})
As you see here, the columns are rendered generically and they use the cellComponent property to determine which component type to render.
Related
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.
Our Application has components which consume components with consume components of varying complexity. So i just want the input on the page, to validate when an object is set that the text is correct. The issue is that it is one of these subcomponents.
My colleague told me that there is 2 ways to do this, The first is to use Page Objects, and Chaining annotation to find it on my page, and then find the next id etc until my input is found. It requires me to look through another teams' Component Markup to narrow it down to the input i want to leverage. I dont believe I should have to go into another component definition, or a definition of a definition to get the appropriate chain to get this arbitrary input. It starts to create issues where if a lateral team creates changes unbeknownst to me, my PO will be broken.
The other option my friend asked was to use fixture.query to find the component. This would be as simple as:
fixture.query((el)=> el.attribute["id"] == "description",
(comp){
expect(comp.value, value);
});`
Using Query looks at the markup but then will automatically componentize it as the appropriate SubComponent. In this case, comp.value is the value stored in the HTML. So, if i did something like:
fixture.update((MainComponent comp) {
comp.myinput.value = new Foo();
});
Then I am setting and getting this programmatically, so i am a bit unsure if it properly would reflect what is on the screen.
Whats the best course of action? It seems PO would be better, but im not sure if there is a way around having to deep query for input boxes outside of the component i am testing.
Thanks
I don't think I have a definitive answer for you but I can tell you how we do it at Google. For pretty much any component we provide the page object alongside the component. This is twofold it is for testing that widget, and also so we can have this as a shareable resource for other tests.
For leaf widgets the page objects are a little less fleshed out and are really just there for the local test. For components that are shared heavily the page object is a bit more flushed out for reusability. Without this much of the API for the widget (html, css, etc) we would need to consider public and changes to them would be very hard (person responsible for making the public breaking change needs to fix all associated code.) With it we can have a contract to only support the page object API and html structure changes are not considered breaking changes. At times we have even gone so far as to have two page objects for a widget. One for the local test, and one to share. Sometimes the API you want to expose for a local test is much more than you want people to use themselves.
We can then compose these page objects into higher level page objects that represent the widget. Good page objects support a higher level of abstraction for that widget. For example a calendar widget would let you go to the next/previous month, get the current selected date, etc. rather than directly exposing the buttons/inputs that accomplish those actions.
We plan to expose these page objects for angular_components eventually, but we are currently working on how to expose these. Our internal package structure is different than what we have externally. We have many packages per individual widget (page_objects, examples, widget itself) and we need to reconcile this externally before we expose them.
Here is an example:
import 'package:pageloader/objects.dart';
import 'material_button_po.dart';
/// Webdriver page object for `material-yes-no-buttons` component.
#EnsureTag('material-yes-no-buttons')
class MaterialYesNoButtonsPO {
#ByClass('btn-yes')
#optional
MaterialButtonPO yesButton;
#ByClass('btn-no')
#optional
MaterialButtonPO noButton;
}
I know this question might seem a little duplicate but the other version of this question is old and some of the content (such as Views) aren't even a part of ember anymore.
I'm about 4 weeks into my internship as a front-end developer working with EmberJS. I still don't understand when it's better to use the route over the controller or vice-versa. It seems to me that every action in the route can also be used in the controller.
The one recent thing I heard was that ember routes should be stateless where as controllers should be stateful.
What is the current state of controllers and routes. When should one be used over the other?
Consider the following example to understand the state of a controller (or route, or anything), in simple terms and in current context -- lets say you have a page (like a form) with three tabs; each tab can be considered as a state - it would call different components based on the state (or the tab you are in). Now if you would happen to go back for some reason, and hit the form link again, you would see that the state would remain the same. (if you were on tab 2 when you hit back, on returning to the form, you would still be on tab 2).
So to maintain these states, controllers are the way to go, since they are singletons. Route would have lost that information, and started fresh. So basically your variables/objects in a controller would define the 'state'.
Route-actions can be as easily used as controller actions- see https://github.com/DockYard/ember-route-action-helper. So if your template for this route is just using model as the object directly, and you don't need to maintain the 'state', you can pretty much do without your controller.
But if your template was using variables which needed manipulation, you would need controller.
Hope this helps!
I'm looking at creating a google maps component. But I would like it to be self contained so it will have its own model, controllers and views. So for example the component will fetch its own data from the server and I'll also be able to refresh the data when needed. Ideally I'd simply add the component to the current template that is showing, so for example: {{map-view}} and then everything the component needs to do will take care of its self.
The component will also need to listen to triggered events from other controllers as a user will be able to search for a specific location and the map will need to change its position.
Is this possible to do in EmberJS? As I haven't found anything like this, specially when having its own model. I know there is a component in EmberJS but it seems very limited. Am I wrong in thinking this?
the controller cannot have its own model all values must be passed to component. Please refer to ember docs and this Discussion
You can make a google map component and pass the location and marker data to the component. this data will get updated due to ember data binding.
so you can have something like this
{{map-view location=userEnteredValue}}
you can search for ember component talk by Kris Selden on youtube which includes a google map component good for you to start with.
updated
https://gist.github.com/krisselden/8189650
I am listing products as table rows, each row contains input fields for specifying the quantity of products.
I made a Fiddle for it here, http://jsfiddle.net/kroofy/4jTa8/19/
As you can see, after the input in the Qty field have been made, the whole row render again. And because of that the focus of the input field will be lost, which is not good if you want to input more than just one digit, or tab between input fields.
What would be the most elegant way to solve this?
I would handle this by setting model.set({qty: _qty}, {silent: true}) and then updating the non-input fields with this.$.
As an alternative to the silent treatment: rather than listening for change events, listen for change:qty and change:sellPrice and have a method that updates just the HTML that needs updating within this.$, rather than re-rendering the DOM object and breaking your focus.
Either way, your comment about "selective updating" on the fiddle is certainly the right way to go.
(this.$ is a backbone hack to jQuery that restricts all selectors to search only within the DOM of the View's element. The element doesn't even need an ID or class; it just needs to exist and the View maintains a handle to it. It's incredibly useful.)
i built a plugin for backbone called Backbone.ModelBinding that may be able to help in this situation. my plugin allows you to update portions of a view with data from a model, when the model changes.
i've forked / updated your fiddle to show it in action: http://jsfiddle.net/derickbailey/FEcyF/6/
i removed the binding to the model change. i've also added id attributes to the inputs of the form to facilitate the plugin (the attribute that the plugin uses is configurable, though). and lastly, i've added a data-bind attribute to the sell price total td.
you can get the plugin here: http://github.com/derickbailey/backbone.modelbinding/
hope that helps
FWIW: my plugin is an automated version of what Elf is suggesting. I've written code exactly like he is describing, numerous times, which is where the plugin came from. I just got tired of writing that code by hand :)