c1440e7eff
New Dart prose, update Dart and Ts code + guide/server-communication/ts: update to docs and example code + guide/server-communication/dart: new prose, update example code + ignore all npm-debug.logs + make Jade ul li TOC elements more compact.
83 lines
3.3 KiB
Plaintext
83 lines
3.3 KiB
Plaintext
extends ../../../ts/latest/guide/server-communication.jade
|
|
|
|
block includes
|
|
include ../_util-fns
|
|
|
|
block http-providers
|
|
//- TODO(chalin): mention the Angular transformer resolved_identifiers.
|
|
//- Maybe not yet at this point in the chapter.
|
|
|
|
block getheroes-and-addhero
|
|
:marked
|
|
The hero service `getHeroes()` and `addHero()` asynchronous methods return the
|
|
[`Future`](https://api.dartlang.org/stable/1.16.0/dart-async/Future-class.html)
|
|
values of the current hero list and the newly added hero,
|
|
respectively. The hero list component methods of the same name specifying
|
|
the actions to be taken when the asynchronous method calls succeed or fail.
|
|
|
|
For more information about `Future`s, consult any one
|
|
of the [articles](https://www.dartlang.org/articles/) on asynchronous
|
|
programming in Dart, or the tutorial on
|
|
[_Asynchronous Programming: Futures_](https://www.dartlang.org/docs/tutorials/futures/).
|
|
|
|
block http-client-service
|
|
:marked
|
|
The imported `BrowserClient` client service gets
|
|
[injected](dependency-injection.html) into the `HeroService` constructor.
|
|
Note that `BrowserClient` is not part of the Angular core.
|
|
It's an optional service provided by the Dart
|
|
[`http` package](https://pub.dartlang.org/packages/http).
|
|
|
|
block rxjs
|
|
//- N/A
|
|
|
|
block non-success-status-codes
|
|
:marked
|
|
Because a status code outside the 200-299 range _is an error_ from the
|
|
application point of view, we test for this condition and throw an
|
|
exception when detected.
|
|
|
|
block parse-json
|
|
:marked
|
|
The response data are in JSON string form.
|
|
We must parse that string into JavaScript objects which we do by calling
|
|
the `JSON.decode()` method from the `dart:convert` library.
|
|
|
|
block error-handling
|
|
//- TODO: describe `_handleError`?
|
|
|
|
block hlc-error-handling
|
|
:marked
|
|
Back in the `HeroListComponent`, we wrapped our call to
|
|
`#{_priv}heroService.getHeroes()` in a `try` clause. When an exception is
|
|
caught, the `errorMessage` variable — which we've bound conditionally in the
|
|
template — gets assigned to.
|
|
|
|
block hero-list-comp-add-hero
|
|
:marked
|
|
Back in the `HeroListComponent`, we see that *its* `addHero()`
|
|
awaits for the *service's* asynchronous `addHero()` to return, and when it does,
|
|
the new hero is added to the `heroes` list for presentation to the user.
|
|
+makeExample('server-communication/ts/app/toh/hero-list.component.ts', 'addHero', 'app/toh/hero-list.component.ts (addHero)')(format=".")
|
|
|
|
block promises
|
|
//- N/A
|
|
|
|
block wikipedia-jsonp+
|
|
:marked
|
|
Wikipedia offers both `CORS` and `JSONP` search APIs.
|
|
.alert.is-important
|
|
:marked
|
|
The remaining content of this section is coming soon.
|
|
In the meantime, consult the
|
|
[example sources](https://github.com/angular-examples/server-communication)
|
|
to see how to access Wikipedia via its `JSONP` API.
|
|
|
|
block redirect-to-web-api
|
|
:marked
|
|
To achieve this, we have Angular inject an in-memory web API server
|
|
instance as a provider for the `BrowserClient`. This is possible because
|
|
the in-memory web API server class extends `BrowserClient`. Here are the
|
|
pertinent details, excerpt from `TohComponent`:
|
|
+makeExample('server-communication/ts/app/toh/toh.component.ts', 'in-mem-web-api', 'app/toh.component.ts (excerpt)')(format=".")
|