Angular 组件命名限制 - “选择器 [您的组件名称] 无效" [英] Angular component naming limitations - 'selector [your component name] is invalid'

问题描述

在 Angular 6 (6.0.7) 中，我试图通过 CLI 生成一个组件.我输入 ng gc t1-2-3-user 并收到错误消息 Selector (app-t1-2-3-user) is invalid.

In Angular 6 (6.0.7) I'm trying to generate a component via the CLI. I type in ng g c t1-2-3-user and get the error message Selector (app-t1-2-3-user) is invalid.

此名称中是否存在固有不允许的内容?我已经通过 ng g module t1-myModule 创建了一个名为 t1-myModule 的父模块，并且它已成功创建.在那个模块中，我试图生成这个组件.

Is there something inherently not allowed in this name? I've already created a parent module called t1-myModule via ng g module t1-myModule and it was created successfully. Within that module is where I'm trying to generate this component.

我尝试创建一个不同的名称，例如 ng g c t1-testComponent 并且它工作正常 - 因此 CLI 似乎没有损坏.Angular 不喜欢在我的设置中命名组件 t1-2-3-user.

I've tried creating a different name like ng g c t1-testComponent and it works fine - so the CLI doesn't appear to be broken. Something about naming a component t1-2-3-user in my setup is not liked by Angular.

经过进一步测试，似乎 Angular 不喜欢破折号 - 后的第一个字符是数字.可能与 JavaScript 变量类似的限制.我假设因为它被编译成 JavaScript?谁能详细说明/确认此组件命名约束?

after further testing, it appears Angular doesn't like the first character after a dash - to be a number. Possibly a similar limitation as in JavaScript variables. I assume since it gets compiled into JavaScript? Can anyone elaborate on/confirm this component naming constraint?

推荐答案

根据 W3C 标准 选择器应符合以下条件

As per W3C standards selector should qualify below set of things

在 CSS 中，标识符(包括元素名称、类和 ID)选择器)可以包含

In CSS, identifiers (including element names, classes, and IDs in selectors) can contain

1. 仅字符 [a-zA-Z0-9] 和 ISO 10646 字符 U+00A0 及更高，加上连字符 (-) 和下划线 (_)；
2. 不能以数字、两个连字符或连字符开头一个数字
3. 标识符还可以包含转义字符和任何 ISO 10646 字符作为数字代码(见下一项).例如，标识符B&W?"可以写成B\&W\?"或B\26 W\3F".

所以 Angular 遵循 W3C 的选择器名称约定.我预计会在某个地方的内部代码中看到类似的东西.深入 CLI 代码后发现 angular 使用正则表达式 (/^[a-zA-Z][.0-9a-zA-Z]*(:?-[a-zA-Z][.0-9a-zA-Z]*)*$/) 在创建文件之前验证 selector 名称.

So Angular is following the W3C convention for selector name. I was expected to see similar thing baked in inside code somewhere. After digging into CLI code It turns out that angular uses regex (/^[a-zA-Z][.0-9a-zA-Z]*(:?-[a-zA-Z][.0-9a-zA-Z]*)*$/) to validate selector name before creating files.

因此，在运行 ng generate component component-name 命令时，它会为 component 命令调用 @angular/schematics 并将组件名称参数传递给它.在使用指令集执行命令时，它会触发 下面一行 来验证选择器.

So while running ng generate component component-name command it calls @angular/schematics for component command and pass the component name parameter to it. While executing command with set of instruction it fires below line to validate selector.

validateHtmlSelector(options.selector);

验证.ts

export const htmlSelectorRe = /^[a-zA-Z][.0-9a-zA-Z]*(:?-[a-zA-Z][.0-9a-zA-Z]*)*$/;
export function validateHtmlSelector(selector: string): void {
  if (selector && !htmlSelectorRe.test(selector)) {
    throw new SchematicsException(tags.oneLine`Selector (${selector})
        is invalid.`);
  }
}

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