Angular 6 error show to 'mat-form-field' is not a known element:

Question

Hi I am using angular 6 and my code is as follows:

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 { }

and html like this

<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>

my package like this

"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"
  },

and I get to this error

'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. ("

why I get to this error I have to spend too many times to resolve to this but not getting any solution where I am wrong I also search to stack overflow here some find the solution but not resolve to my problem can you please help me find out to this error

Thanks for solving my problem

Answer 1

Looking at your error ng:///AppRoutingModule/LoginComponent.html@11:2

i can conclude that you declared LoginComponent in AppRoutingModule but didn't import MatFormFieldModule there.

Either move LoginComponent to decrations array of AppModule:

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

or import MatFormFieldModule or some SharedModule in AppRoutingModule:

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

See also:

• Angular 2 Use component from another module