From 60f761b4c2d81243f93431327c56101e8bd013fe Mon Sep 17 00:00:00 2001 From: David Shevitz Date: Thu, 17 Sep 2020 16:39:51 +0000 Subject: [PATCH] docs: deprecate displaying data in views topic (#38885) The Displaying Data in Views topic is actually a small tutorial that describes Angular features such as interpolation and structural directives. These content is already covered in our getting started tutorial and in Tour of Heroes. This change adds redirects to the Template Syntax section of the Getting Started tutorial and deletes displaying-data.md. PR Close #38885 --- aio/content/guide/architecture-components.md | 6 +- aio/content/guide/architecture-next-steps.md | 7 +- aio/content/guide/displaying-data.md | 312 ------------------ aio/content/guide/user-input.md | 4 +- aio/content/guide/zone.md | 8 +- aio/content/navigation.json | 5 - aio/firebase.json | 1 + aio/ngsw-config.json | 3 + .../deployment/shared/URLS_TO_REDIRECT.txt | 1 + 9 files changed, 16 insertions(+), 331 deletions(-) delete mode 100644 aio/content/guide/displaying-data.md diff --git a/aio/content/guide/architecture-components.md b/aio/content/guide/architecture-components.md index bedc446a51..df3de2d587 100644 --- a/aio/content/guide/architecture-components.md +++ b/aio/content/guide/architecture-components.md @@ -89,7 +89,7 @@ This example from the `HeroListComponent` template uses three of these forms. -* The `{{hero.name}}` [*interpolation*](guide/displaying-data#interpolation) +* The `{{hero.name}}` [*interpolation*](guide/interpolation) displays the component's `hero.name` property value within the `
  • ` element. * The `[hero]` [*property binding*](guide/property-binding) passes the value of @@ -166,8 +166,8 @@ The example template uses two built-in structural directives to add application -* [`*ngFor`](guide/displaying-data#ngFor) is an iterative; it tells Angular to stamp out one `
  • ` per hero in the `heroes` list. -* [`*ngIf`](guide/displaying-data#ngIf) is a conditional; it includes the `HeroDetail` component only if a selected hero exists. +* [`*ngFor`](guide/structural-directives#inside-ngfor) is an iterative; it tells Angular to stamp out one `
  • ` per hero in the `heroes` list. +* [`*ngIf`](guide/structural-directives#ngif-case-study) is a conditional; it includes the `HeroDetail` component only if a selected hero exists. #### Attribute directives diff --git a/aio/content/guide/architecture-next-steps.md b/aio/content/guide/architecture-next-steps.md index 4ffd41dc44..899a4ef8c8 100644 --- a/aio/content/guide/architecture-next-steps.md +++ b/aio/content/guide/architecture-next-steps.md @@ -11,7 +11,7 @@ about the features and tools that can help you develop and deliver Angular appli ## Application architecture -* The [Components and templates](guide/displaying-data) guide explains how to connect the application data in your [components](guide/glossary#component) to your page-display [templates](guide/glossary#template), to create a complete interactive application. +* The **Main Concepts** section located in the table of contents contains several topics that explain how to connect the application data in your [components](guide/glossary#component) to your page-display [templates](guide/glossary#template), to create a complete interactive application. * The [NgModules](guide/ngmodules) guide provides in-depth information on the modular structure of an Angular application. @@ -21,7 +21,7 @@ about the features and tools that can help you develop and deliver Angular appli ## Responsive programming -The **Components and Templates** guide provides guidance and details of the [template syntax](guide/template-syntax) that you use to display your component data when and where you want it within a view, and to collect input from users that you can respond to. +The [template syntax](guide/template-syntax) and related topics contain details about how to display your component data when and where you want it within a view, and how to collect input from users that you can respond to. Additional pages and sections describe some basic programming techniques for Angular apps. @@ -52,8 +52,6 @@ For some platforms and applications, you might also want to use the PWA (Progres ## Support for the development cycle -The **Development Workflow** section describes the tools and processes you use to compile, test, and deploy Angular applications. - * [CLI Command Reference](cli): The Angular CLI is a command-line tool that you use to create projects, generate application and library code, and perform a variety of ongoing development tasks such as testing, bundling, and deployment. * [Compilation](guide/aot-compiler): Angular provides just-in-time (JIT) compilation for the development environment, and ahead-of-time (AOT) compilation for the production environment. @@ -68,7 +66,6 @@ The **Development Workflow** section describes the tools and processes you use t * [Accessibility](guide/accessibility): Make your app accessible to all users. - ## File structure, configuration, and dependencies * [Workspace and file structure](guide/file-structure): Understand the structure of Angular workspace and project folders. diff --git a/aio/content/guide/displaying-data.md b/aio/content/guide/displaying-data.md deleted file mode 100644 index e7e78b1bf5..0000000000 --- a/aio/content/guide/displaying-data.md +++ /dev/null @@ -1,312 +0,0 @@ -# Displaying data in views - -Angular [components](guide/glossary#component) form the data structure of your application. -The HTML [template](guide/glossary#template) associated with a component provides the means to display that data in the context of a web page. -Together, a component's class and template form a [view](guide/glossary#view) of your application data. - -The process of combining data values with their representation on the page is called [data binding](guide/glossary#data-binding). -You display your data to a user (and collect data from the user) by *binding* controls in the HTML template to the data properties of the component class. - -In addition, you can add logic to the template by including [directives](guide/glossary#directive), which tell Angular how to modify the page as it is rendered. - -Angular defines a *template language* that expands HTML notation with syntax that allows you to define various kinds of data binding and logical directives. -When the page is rendered, Angular interprets the template syntax to update the HTML according to your logic and current data state. -Before you read the complete [template syntax guide](guide/template-syntax), the exercises on this page give you a quick demonstration of how template syntax works. - -In this demo, you'll create a component with a list of heroes. -You'll display the list of hero names and conditionally show a message below the list. -The final UI looks like this: - -
    - Final UI -
    - -
    - -The demonstrates all of the syntax and code snippets described in this page. - -
    - -{@a interpolation} - -## Showing component properties with interpolation -The easiest way to display a component property is to bind the property name through interpolation. -With interpolation, you put the property name in the view template, enclosed in double curly braces: `{{myHero}}`. - -Use the CLI command [`ng new displaying-data`](cli/new) to create a workspace and app named `displaying-data`. - -Delete the app.component.html file. It is not needed for this example. - -Then modify the app.component.ts file by -changing the template and the body of the component. - -When you're done, it should look like this: - - - -You added two properties to the formerly empty component: `title` and `myHero`. - -The template displays the two component properties using double curly brace -interpolation: - - - -
    - -The template is a multi-line string within ECMAScript 2015 backticks (\`). -The backtick (\`)—which is *not* the same character as a single -quote (`'`)—allows you to compose a string over several lines, which makes the -HTML more readable. - -
    - -Angular automatically pulls the value of the `title` and `myHero` properties from the component and -inserts those values into the browser. Angular updates the display -when these properties change. - -
    - -More precisely, the redisplay occurs after some kind of asynchronous event related to -the view, such as a keystroke, a timer completion, or a response to an HTTP request. - -
    - -Notice that you don't call **new** to create an instance of the `AppComponent` class. -Angular is creating an instance for you. How? - -The CSS `selector` in the `@Component` decorator specifies an element named ``. -That element is a placeholder in the body of your `index.html` file: - - - -When you bootstrap with the `AppComponent` class (in main.ts), Angular looks for a `` -in the `index.html`, finds it, instantiates an instance of `AppComponent`, and renders it -inside the `` tag. - -Now run the app. It should display the title and hero name: - -
    - Title and Hero -
    - -The next few sections review some of the coding choices in the app. - - -## Choosing the template source - -The `@Component` metadata tells Angular where to find the component's template. -You can store your component's template in one of two places. - -* You can define the template *inline* using the `template` property of the `@Component` decorator. An inline template is useful for a small demo or test. -* Alternatively, you can define the template in a separate HTML file and link to that file in the `templateUrl` property of the `@Component` decorator. This configuration is typical for anything more complex than a small test or demo, and is the default when you generate a new component. - -In either style, the template data bindings have the same access to the component's properties. -Here the app uses inline HTML because the template is small and the demo is simpler without the additional HTML file. - -
    - - By default, the Angular CLI command [`ng generate component`](cli/generate) generates components with a template file. - You can override that by adding the "-t" (short for `inlineTemplate=true`) option: - - - ng generate component hero -t - - -
    - - -## Initialization - -The following example uses variable assignment to initialize the components. - - - - You could instead declare and initialize the properties using a constructor. - This app uses more terse "variable assignment" style simply for brevity. - - -{@a ngFor} - -## Add logic to loop through data - -The `*ngFor` directive (predefined by Angular) lets you loop through data. The following example uses the directive to show all of the values in an array property. - -To display a list of heroes, begin by adding an array of hero names to the component and redefine `myHero` to be the first name in the array. - - - - - -Now use the Angular `ngFor` directive in the template to display each item in the `heroes` list. - - - - - -This UI uses the HTML unordered list with `
      ` and `
    • ` tags. The `*ngFor` -in the `
    • ` element is the Angular "repeater" directive. -It marks that `
    • ` element (and its children) as the "repeater template": - - - - -
      - -Don't forget the leading asterisk (\*) in `*ngFor`. It is an essential part of the syntax. -Read more about `ngFor` and `*` in the [ngFor section](guide/built-in-directives#ngfor) of the [Built-in directives](guide/built-in-directives) page. - -
      - -Notice the `hero` in the `ngFor` double-quoted instruction; -it is an example of a template input variable. Read -more about template input variables in the [microsyntax](guide/built-in-directives#microsyntax) section of -the [Built-in directives](guide/built-in-directives) page. - -Angular duplicates the `
    • ` for each item in the list, setting the `hero` variable -to the item (the hero) in the current iteration. Angular uses that variable as the -context for the interpolation in the double curly braces. - -
      - -In this case, `ngFor` is displaying an array, but `ngFor` can -repeat items for any [iterable](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols) object. - -
      - -Now the heroes appear in an unordered list. - -
      - After ngfor -
      - - -## Creating a class for the data - -The app's code defines the data directly inside the component, which isn't best practice. -In a simple demo, however, it's fine. - -At the moment, the binding is to an array of strings. -In real applications, most bindings are to more specialized objects. - -To convert this binding to use specialized objects, turn the array -of hero names into an array of `Hero` objects. For that you'll need a `Hero` class: - - - ng generate class hero - - -This command creates the following code. - - - - -You've defined a class with a constructor and two properties: `id` and `name`. - -It might not look like the class has properties, but it does. -The declaration of the constructor parameters takes advantage of a TypeScript shortcut. - -Consider the first parameter: - - - - -That brief syntax does a lot: - -* Declares a constructor parameter and its type. -* Declares a public property of the same name. -* Initializes that property with the corresponding argument when creating an instance of the class. - - -### Using the Hero class - -After importing the `Hero` class, the `AppComponent.heroes` property can return a _typed_ array -of `Hero` objects: - - - - - - -Next, update the template. -At the moment it displays the hero's `id` and `name`. -Fix that to display only the hero's `name` property. - - - - - -The display looks the same, but the code is clearer. - -{@a ngIf} - -## Conditional display with NgIf - -Sometimes an app needs to display a view or a portion of a view only under specific circumstances. - -Let's change the example to display a message if there are more than three heroes. - -The Angular `ngIf` directive inserts or removes an element based on a _truthy/falsy_ condition. -To see it in action, add the following paragraph at the bottom of the template: - - - - - -
      - -Don't forget the leading asterisk (\*) in `*ngIf`. It is an essential part of the syntax. -Read more about `ngIf` and `*` in the [ngIf section](guide/built-in-directives#ngIf) of the [Built-in directives](guide/built-in-directives) page. - -
      - - -The template expression inside the double quotes, -`*ngIf="heroes.length > 3"`, looks and behaves much like TypeScript. -When the component's list of heroes has more than three items, Angular adds the paragraph -to the DOM and the message appears. -If there are three or fewer items, Angular omits the paragraph, so no message appears. - -For more information, see [template expression operators](guide/interpolation#template-expressions). - - -
      - -Angular isn't showing and hiding the message. It is adding and removing the paragraph element from the DOM. That improves performance, especially in larger projects when conditionally including or excluding -big chunks of HTML with many data bindings. - -
      - -Try it out. Because the array has four items, the message should appear. -Go back into app.component.ts and delete or comment out one of the elements from the heroes array. -The browser should refresh automatically and the message should disappear. - - -## Summary -Now you know how to use: - -* **Interpolation** with double curly braces to display a component property. -* **ngFor** to display an array of items. -* A TypeScript class to shape the **model data** for your component and display properties of that model. -* **ngIf** to conditionally display a chunk of HTML based on a boolean expression. - -Here's the final code: - - - - - - - - - - - - - - - - - - - - diff --git a/aio/content/guide/user-input.md b/aio/content/guide/user-input.md index 3c88c2f126..19907e16a1 100644 --- a/aio/content/guide/user-input.md +++ b/aio/content/guide/user-input.md @@ -234,8 +234,8 @@ To fix this issue, listen to both the _Enter_ key and the _blur_ event. ## Put it all together -The previous page showed how to [display data](guide/displaying-data). -This page demonstrated event binding techniques. + +This page demonstrated several event binding techniques. Now, put it all together in a micro-app that can display a list of heroes and add new heroes to the list. diff --git a/aio/content/guide/zone.md b/aio/content/guide/zone.md index 7b17ef9b8a..acafca0602 100644 --- a/aio/content/guide/zone.md +++ b/aio/content/guide/zone.md @@ -9,7 +9,7 @@ To understand the benefits of `NgZone`, it is important to have a clear grasp of ### Displaying and updating data in Angular -In Angular, you can [display data](guide/displaying-data) by binding controls in an HTML template to the properties of an Angular component. +In Angular, you can display data by binding controls in an HTML template to the properties of an Angular component. @@ -102,13 +102,13 @@ In Angular, this step is unnecessary. Whenever you update the data, your HTML is To understand how change detection works, first consider when the application needs to update the HTML. Typically, updates occur for one of the following reasons: -1. Component initialization. For example, when bootstrapping an Angular application, Angular loads the bootstrap component and triggers the [ApplicationRef.tick()](api/core/ApplicationRef#tick) to call change detection and View Rendering. Just as in the [displaying data](guide/displaying-data) sample, the `AppComponent` is the bootstrap component. This component has the properties `title` and `myHero`, which the application renders in the HTML. +1. Component initialization. For example, when bootstrapping an Angular application, Angular loads the bootstrap component and triggers the [ApplicationRef.tick()](api/core/ApplicationRef#tick) to call change detection and View Rendering. -2. Event listener. The DOM event listener can update the data in an Angular component and also trigger change detection, as in the following example. +1. Event listener. The DOM event listener can update the data in an Angular component and also trigger change detection, as in the following example. -3. HTTP Data Request. You can also get data from a server through an HTTP request. For example: +1. HTTP Data Request. You can also get data from a server through an HTTP request. For example: ```typescript @Component({ diff --git a/aio/content/navigation.json b/aio/content/navigation.json index c67a25b3ff..8316bb543d 100644 --- a/aio/content/navigation.json +++ b/aio/content/navigation.json @@ -609,11 +609,6 @@ "title": "Building a Template-driven Form", "tooltip": "Create a template-driven form using directives and Angular template syntax." }, - { - "url": "guide/displaying-data", - "title": "Data binding", - "tooltip": "Property binding helps show app data in the UI." - }, { "url": "guide/web-worker", "title": "Web Workers", diff --git a/aio/firebase.json b/aio/firebase.json index a25994b18b..033674d538 100644 --- a/aio/firebase.json +++ b/aio/firebase.json @@ -31,6 +31,7 @@ {"type": 301, "source": "/guide/quickstart", "destination": "/start"}, {"type": 301, "source": "/getting-started", "destination": "/start"}, {"type": 301, "source": "/getting-started/:rest*", "destination": "/start/:rest*"}, + {"type": 301, "source": "/guide/displaying-data", "destination": "/start#template-syntax"}, // Renaming of Getting Started topics {"type": 301, "source": "/start/data", "destination": "/start/start-data"}, diff --git a/aio/ngsw-config.json b/aio/ngsw-config.json index 7de07ae773..28fd8f79c9 100644 --- a/aio/ngsw-config.json +++ b/aio/ngsw-config.json @@ -102,6 +102,9 @@ "!/guide/cli-quickstart", "!/guide/cli-quickstart.html", "!/guide/cli-quickstart/", + "!/guide/displaying-data", + "!/guide/displaying-data.html", + "!/guide/displaying-data/", "!/guide/learning-angular", "!/guide/learning-angular.html", "!/guide/learning-angular/", diff --git a/aio/tests/deployment/shared/URLS_TO_REDIRECT.txt b/aio/tests/deployment/shared/URLS_TO_REDIRECT.txt index 23a6370555..887ad52883 100644 --- a/aio/tests/deployment/shared/URLS_TO_REDIRECT.txt +++ b/aio/tests/deployment/shared/URLS_TO_REDIRECT.txt @@ -177,6 +177,7 @@ /getting-started/forms /start/start-forms /getting-started/deployment /start/start-deployment /guide/cli-quickstart /start +/guide/displaying-data /start#template-syntax /guide/learning-angular /start /guide/learning-angular.html /start /guide/metadata /guide/aot-compiler