Angular 6/7“依赖的结果是一个表达式" [英] Angular 6 / 7 "the result of a dependency is an expression"

问题描述

我正在尝试创建一个 Angular 6 库并在 Angular 6 应用程序中使用它.我已经把它归结为一个最小的测试用例.(更新:由于 Angular 7 已经发布，我也试过了.)

I'm trying to create an Angular 6 library and use it in an Angular 6 app. I've boiled it down to a minimal test case. (Update: since Angular 7 is out, I've tried that as well.)

ng new workspace # accept the defaults
ng new product # accept the defaults
cd workspace 
ng generate library widgets 
ng build --prod widgets # leave out "--prod" for Angular 7
cd ../product
ng build

名为workspace"的应用托管了一个名为widgets"的库.另一个名为产品"的应用程序独立存在.到目前为止一切都很好.

An app called "workspace" hosts a library called "widgets". Another app called "product" stands alone. Everything to this point is fine.

现在让我们尝试使用产品"应用中的小部件"库.打开由 CLI 生成的文件 product/src/app/app.module.ts.添加两行，如下所示.

Now let's try using the "widgets" library in the "product" app. Open the file product/src/app/app.module.ts which was generated by the CLI. Add two lines as shown below.

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';
import { WidgetsModule } from '../../../workspace/dist/widgets'; //  added

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    WidgetsModule // added
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

更改后，当我从产品目录运行 ng build 时，我收到来自 Webpack 的警告.

After that change, when I run ng build from the product directory, I get warnings from Webpack.

Date: 2018-07-31T13:13:08.001Z
Hash: 8a6f58d2ae959edb3cc8
Time: 8879ms
chunk {main} main.js, main.js.map (main) 15.9 kB [initial] [rendered]
chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 227 kB [initial] [rendered]
chunk {runtime} runtime.js, runtime.js.map (runtime) 5.22 kB [entry] [rendered]
chunk {styles} styles.js, styles.js.map (styles) 15.6 kB [initial] [rendered]
chunk {vendor} vendor.js, vendor.js.map (vendor) 4.59 MB [initial] [rendered]

WARNING in ../workspace/node_modules/@angular/core/fesm5/core.js
4997:15-36 Critical dependency: the request of a dependency is an expression

WARNING in ../workspace/node_modules/@angular/core/fesm5/core.js
5009:15-102 Critical dependency: the request of a dependency is an expression

依赖的结果是一个表达式"是什么意思?我做错了什么?

What does "the result of a dependency is an expression" mean? What am I doing wrong?

推荐答案

主要问题不是为什么会收到警告.您访问图书馆的方式不是理想的方式.让我们用您自己的示例步骤研究一个更好的方法 [使用 Angular 7]，这首先不会导致该问题.

The main problem is not why you are getting that warnings. The way you are accessing the library is not an ideal way. Let's look into a little better approach [Using Angular 7] with your own sample steps, which will not cause that issue in the first place.

ng new workspace # accept the defaults
ng new product # accept the defaults
cd workspace 
ng generate library widgets 
ng build --prod widgets # leave out "--prod" for Angular 7
cd ../product
ng build

<小时>

第 2 步:创建 .tgz 库文件

cd ../workspace/dist/widgets/
npm pack
cp widgets-0.0.1.tgz ../../../product/

<小时>

第 3 步:在 package.json 中添加widgets"库

打开product项目的package.json文件，在devDependencies下添加如下一行:

---

Step 3: Add "widgets" library in package.json

Open package.json file of product project, and under devDependencies add the following line:

"widgets": "file:./widgets-0.0.1.tgz",

如果您在本地拥有库，则需要执行第 2 步和第 3 步.否则，如果您的库已打包并发布到 npm 存储库中，则您不需要 file: 关键字.您可以像其他依赖项一样提及版本.

Step 2 and Step 3 are required if you have the library locally. Otherwise, if your library is packed and publish into npm repository, then you don't need file: keyword. You can just mention the version like other dependencies.

在产品项目中运行 npm install.

修改app.module.ts文件:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';
import { WidgetsModule } from 'widgets'; // new line

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    WidgetsModule // new line
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

<小时>

第 6 步:构建产品项目

现在，在产品项目中运行 ng build.它将成功运行.

这篇关于Angular 6/7“依赖的结果是一个表达式"的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！