“mat-form-field”中的Angular 6错误显示不是已知元素：

Question

嗨我使用角度6，我的代码如下：

import { BrowserModule } from '@angular/platform-browser';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { RouterModule, Routes } from '@angular/router';




import { AppComponent } from './app.component';
import { AppRoutingModule } from './app.routing.module';


import { MatButtonModule, MatFormFieldModule, MatInputModule, MatRippleModule } from '@angular/material';
//import { MaterialModule } from 'src/app/et-shared/material.module';


const modules = [
  MatButtonModule,
  MatFormFieldModule,
  MatInputModule,
  MatRippleModule
];

@NgModule({
  declarations: [
    AppComponent,
  ],
  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    CommonModule,
    RouterModule,
    AppRoutingModule,
   // MaterialModule,
   ...modules

  ],
  exports:[
    ...modules
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

和这样的HTML

<div class="example-container">
  <mat-form-field>
    <input matInput placeholder="Input">
  </mat-form-field>

  <mat-form-field>
    <textarea matInput placeholder="Textarea"></textarea>
  </mat-form-field>

  <mat-form-field>
    <mat-select placeholder="Select">
      <mat-option value="option">Option</mat-option>
    </mat-select>
  </mat-form-field>
</div>

我的包裹是这样的

"dependencies": {
    "@angular/animations": "^6.0.0",
    "@angular/cdk": "^6.0.1",
    "@angular/common": "^6.0.0",
    "@angular/compiler": "^6.0.0",
    "@angular/core": "^6.0.0",
    "@angular/forms": "^6.0.0",
    "@angular/http": "^6.0.0",
    "@angular/material": "^6.0.1",
    "@angular/platform-browser": "^6.0.0",
    "@angular/platform-browser-dynamic": "^6.0.0",
    "@angular/router": "^6.0.0",
    "core-js": "^2.5.4",
    "hammerjs": "^2.0.8",
    "rxjs": "^6.0.0",
    "zone.js": "^0.8.26"
  },

我得到了这个错误

'mat-form-field' is not a known element:
1. If 'mat-form-field' is an Angular component, then verify that it is part of this module.
2. If 'mat-form-field' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. ("

<div class="example-container">
  [ERROR ->]<mat-form-field>
    <input matInput placeholder="Input">
  </mat-form-field>
"): ng:///AppRoutingModule/LoginComponent.html@7:2
'mat-form-field' is not a known element:
1. If 'mat-form-field' is an Angular component, then verify that it is part of this module.
2. If 'mat-form-field' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. ("
  </mat-form-field>

  [ERROR ->]<mat-form-field>
    <textarea matInput placeholder="Textarea"></textarea>
  </mat-form-field>
"): ng:///AppRoutingModule/LoginComponent.html@11:2
'mat-option' is not a known element:
1. If 'mat-option' is an Angular component, then verify that it is part of this module.
2. If 'mat-option' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. ("
  <mat-form-field>
    <mat-select placeholder="Select">
      [ERROR ->]<mat-option value="option">Option</mat-option>
    </mat-select>
  </mat-form-field>
"): ng:///AppRoutingModule/LoginComponent.html@17:6
'mat-select' is not a known element:
1. If 'mat-select' is an Angular component, then verify that it is part of this module.
2. If 'mat-select' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. ("

为什么我得到这个错误我必须花太多时间来解决这个但没有得到任何解决方案，我错了我也搜索堆栈溢出这里找到解决方案，但没有解决我的问题，请你帮我看看这个错误

谢谢你解决我的问题

Answer 1

看着你的错误ng:///AppRoutingModule/LoginComponent.html@11:2

我可以得出结论，你在LoginComponent宣布AppRoutingModule但没有在那里导入MatFormFieldModule。

要么将LoginComponent移动到decrations的AppModule阵列：

@NgModule({
  declarations: [
    AppComponent,
    LoginComponent
  ],
  ...
})
export class AppModule { }

或者在MatFormFieldModule中导入SharedModule或一些AppRoutingModule：

@NgModule({
  declarations: [
    LoginComponent,
    ...
  ],
  imports: [
    MatFormFieldModule // or SharedModule that exports MatFormFieldModule
    ...
  ]
  ...
})
export class AppRoutingModule { }

也可以看看：

• Angular 2 Use component from another module

Answer 2

尝试导入

import { CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';

在你的模块然后注入

@NgModule({
//..your other property,
   schemas: [CUSTOM_ELEMENTS_SCHEMA]
 });

Answer 3

我有同样的问题，我的修复是MatFormFieldModule，MatInputModule，MatSelectModule，添加到我的Material模块

import { MatFormFieldModule, MatInputModule } from '@angular/material';

@NgModule({
    imports: [
        MatFormFieldModule,
        MatInputModule
    ]
})
export class AppModule { }

Answer 4

如果你有2个App Module例子：app-routing.module.ts和app.module.ts将CommonModule导入到seconde中（app-routing.module.ts）