小编Ста*_*цев的帖子

我收到这个错误，虽然项目中没有一行带有：first-child，为什么会出现？

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 "dependencies": {
    "@storybook/addon-a11y": "^5.1.9",
    "@trendmicro/react-popover": "^0.4.0",
    "@types/classnames": "^2.2.9",
    "@types/jest": "24.0.13",
    "@types/node": "12.0.2",
    "@types/react": "16.8.18",
    "@types/react-dom": "16.8.4",
    "@types/react-modal": "^3.8.2",
    "@types/storybook__addon-a11y": "^5.0.0",
    "@types/storybook__addon-actions": "^3.4.3",
    "@types/storybook__addon-info": "^4.1.1",
    "@types/storybook__addon-knobs": "^5.0.0",
    "@types/storybook__react": "4.0.1",
    "@types/styled-components": "4.1.15",
    "classnames": "^2.2.6",
    "grommet": "^2.7.2",
    "react": "16.8.6",
    "react-dom": "16.8.6",
    "react-modal": "^3.9.1",
    "react-scripts": "3.0.1",
    "react-toastify": "^5.3.2",
    "styled-components": "^4.2.0",
    "typescript": "^3.5.1"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject",
    "storybook": "start-storybook",
    "build-storybook": "build-storybook -c .storybook -o .out",
    "lint": "tslint -c …

我在带有树的材质中找不到表格示例（https://material.angular.io/components/table/examples）。有一个单独的表（MatTableModule）和一棵树（MatTreeModule），但我需要可以将表作为树打开。在表格的大部分组件中，都有这样的机会（https://ggmod.github.io/angular-2-data-table-demo/），但是材料中真的没有吗？任何人都可以看到一个例子吗？你认为在材料表中引入一棵树会有什么困难？

我有哈希问题，在我构建它时在我的工作项目上，在测试项目上一切正常。我已经在谷歌中阅读了这个问题： Angular2 without hash in the url https://forum.ionicframework.com/t/url-routing-without-hash/81140 但我没有找到答案。当我添加

{provide: LocationStrategy, useClass: HashLocationStrategy}

一切正常，但带有哈希值。当我添加

{provide: LocationStrategy, useClass: PathLocationStrategy}

它仅适用于本地版本。但是工作版本不起作用http://joxi.ru/n2YLOaMijK7Pam 我怎样才能删除这个哈希http://joxi.ru/RmzBzxDTWbjeQm它对我的构建项目有什么作用？

app.module.ts

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

import {AppComponent} from './app.component';
import {MaterialModule} from '../shared/mat.module';
import {UserModule} from './user/user.module';
import {BrowserAnimationsModule} from '@angular/platform-browser/animations';
import {AppRoutingModule} from './app-routing.module';
import {ToolbarComponent} from './toolbar/toolbar.component';
import {HashLocationStrategy, LocationStrategy, PathLocationStrategy} from '@angular/common';
import { TestingRComponent } from './testing-r/testing-r.component';

@NgModule({
  declarations: [
    AppComponent,
    ToolbarComponent,
    TestingRComponent
  ],
  imports: [
    BrowserModule,
    MaterialModule,
    UserModule, …

你可以在这里看到我的代码：

https://stackblitz.com/edit/angular-vcjnbf?file=src%2Fapp%2Fapp.component.html

我需要从表中的子元素制作一棵树，现在我这样做了：

但我需要这样：

也就是说，元素有子元素，我只能输出一个，如何在循环中做到这一点？正如您在循环中看到的，我需要调出关卡。

我找到了这样的解决方案，但还有更好的方法吗？

https://stackblitz.com/edit/material2-rc0-oufnyc?file=app/app.component.html

组件.html

    <table mat-table
       [dataSource]="dataSource"
       multiTemplateDataRows
       class="mat-elevation-z8">

  <ng-container matColumnDef="{{column}}"
                *ngFor="let column of columnsToDisplay">
    <th mat-header-cell
        *matHeaderCellDef> {{column}}
    </th>
    <td mat-cell
        *matCellDef="let element">
      {{element[column]}}
    </td>
  </ng-container>

  <ng-container matColumnDef="{{column}}"
                *ngFor="let column of ['expandedDetail', 'expandedDetail1']">
    <td mat-cell
        *matCellDef="let element"
        [attr.colspan]="1"> 111
      ++{{element | json}}++
    </td>
  </ng-container>

  <tr mat-row
      *matRowDef="let element; columns: columnsToDisplay;"
      class="example-element-row"
      [class.example-expanded-row]="expandedElement === element"
      (click)="expandedElement = element">

  </tr>

  <tr mat-row
      *matRowDef="let row; columns: ['expandedDetail', 'expandedDetail1']"
      class="example-detail-row">

  </tr>

</table>

组件.ts

   import {DirectoryService} from '../shared/services/directory.service';
import {Component, …

我正在使用角形材料和反应形式。我想要显示错误消息时，仅显示一条消息，如果解决一个错误，则显示另一条消息。

现在如何：

HTML：

<mat-form-field class="example-full-width">
  <input matInput
         placeholder="Username"
         name="username"
         [formControlName]="'username'">
  <mat-error *ngIf="form.controls['username'].errors && form.controls['username'].touched">
    <div *ngIf="form.controls['username'].errors.required">
      Username is <strong>required</strong>
    </div>
    <div *ngIf="form.controls['username'].errors.minlength">
      Required length: {{form.controls['username'].errors.minlength['requiredLength']}}
      Actual length:{{form.controls['username'].errors.minlength['actualLength']}}
    </div>
    <div *ngIf="form.controls['username'].errors.pattern">
      Only a-zA-Z0-9
    </div>

  </mat-error>

</mat-form-field>

也许我应该使用其他的东西？你怎么看？

我在react上有一个应用程序，当构建时我想插入另一个路径，该怎么办？

我有两个文件的路径需要更改

...................................................... ...................................................... ......................................config.js

const config = {
  url: 'http://45.86.181.235' // here
};

export default config;

包.json

 {
  "name": "celbine",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@babel/core": "7.5.5",
    "@svgr/webpack": "4.3.2",
    "@typescript-eslint/eslint-plugin": "1.13.0",
    "@typescript-eslint/parser": "1.13.0",
    "axios": "^0.19.0",
    "babel-eslint": "10.0.2",
    "babel-jest": "^24.8.0",
    "babel-loader": "8.0.6",
    "babel-plugin-named-asset-import": "^0.3.3",
    "babel-preset-react-app": "^9.0.1",
    "camelcase": "^5.2.0",
    "case-sensitive-paths-webpack-plugin": "2.2.0",
    "chart.js": "^2.8.0",
    "classnames": "^2.2.6",
    "css-loader": "2.1.1",
    "dotenv-expand": "4.2.0",
    "eslint": "^6.1.0",
    "eslint-config-react-app": "^5.0.1",
    "eslint-loader": "2.2.1",
    "eslint-plugin-flowtype": "3.13.0",
    "eslint-plugin-import": "2.18.2",
    "eslint-plugin-jsx-a11y": "6.2.3",
    "eslint-plugin-react": "7.14.3",
    "eslint-plugin-react-hooks": "^1.6.1",
    "file-loader": "3.0.1",
    "font-awesome": "^4.7.0",
    "fs-extra": …

我尝试向数据库中添加一个新用户，一次添加，第二次出现错误

{ MongoError: E11000 重复键错误索引: myproject.users.$username_1 dup key: { : null } at Function.create (D:\projects\myproject\server\node_modules\mongodb-core\lib\error.js:43: 12) 在 toError (D:\projects\myproject\server\node_modules\mongodb\lib\utils.js:149:22) 在 coll.s.topology.insert (D:\projects\myproject\server\node_modules\mongodb\ lib\operations\collection_ops.js:859:39) 在 D:\projects\myproject\server\node_modules\mongodb-core\lib\connection\pool.js:532:18 在 process._tickCallback (internal/process/next_tick. js:61:11) driver: true, name: 'MongoError', index: 0, code: 11000, errmsg: 'E11000重复键错误索引: myproject.users.$username_1 dup key: { : null }', [Symbol (mongoErrorContextSymbol)]: {} }

用户.js

const express = require('express');
const router = express.Router();
const bcrypt = require('bcryptjs');

const validateRegisterInput = require('../../validation/register');

const User = require('../../models/User');

// @route   GET api/users/test
// @desc    Tests users route …

我在数据库中有对象，它们有一个评级对象数组，我需要如果 user\xe2\x80\x99s ID 已在这些对象中，则更新 Rate ，如果没有，则使用以下命令将新对象添加到数组中费率和用户ID

文件图片：

代码 ：

router.post(\'/rating\', (req, res) => {\n // console.log(req.body)\n  let ID = \'f58482b1-ae3a-4d8a-b53b-ede80fe1e225\';\n  // let user = \'5e094d988ddbe02020e13879\';\n  let user = \'asdadasdasd\';\n  Habalka.find({\n      _id: ID\n    },\n    {rating: {$elemMatch: {user}}})\n    .then(res => {\n      if (res[0].rating.length) {\n        // Habalka.updateOne(\n        //   {\n        //     _id: ID,\n        //     \'rating.user\': user\n        //   },\n        //   {$inc:{"rating.$.rate.1":10}}\n        // )\n        //   .then(resUpdate => {\n        //     console.log(resUpdate)\n        //   })\n        // **HERE I …

材料组件中的动画不起作用.我试图把组件sidenav和菜单,平滑的动画不起作用.我认为BrowserAnimationsModule存在问题,因为当我从package.json中删除它时没有任何反应,尽管当你安装材料时它是必需的

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的package.json

   {
  "name": "project",
  "version": "0.0.0",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "^6.0.3",
    "@angular/cdk": "6.1.0",
    "@angular/common": "^6.0.3",
    "@angular/compiler": "^6.0.3",
    "@angular/core": "^6.0.3",
    "@angular/forms": "^6.0.3",
    "@angular/http": "^6.0.3",
    "@angular/material": "6.1.0",
    "@angular/platform-browser": "^6.0.3",
    "@angular/platform-browser-dynamic": "^6.0.3",
    "@angular/router": "^6.0.3",
    "core-js": "^2.5.4",
    "hammerjs": "^2.0.8",
    "rxjs": "^6.0.0",
    "zone.js": "^0.8.26"
  },
  "devDependencies": {
    "@angular/compiler-cli": "^6.0.3",
    "@angular-devkit/build-angular": "~0.6.5",
    "typescript": "~2.7.2",
    "@angular/cli": "~6.0.5",
    "@angular/language-service": "^6.0.3",
    "@types/jasmine": "~2.8.6", …