'mat-form-field' is not a known element - Angular 9 & Material 9.2.0

Question

Hi I am using angular 9 and my code is as follows: HTML component as "post-create.component.html" :

<mat-mat-form-field>
  <textarea rows="6" [(ngModel)]="enteredValue"></textarea>
</mat-mat-form-field>

My app.module.ts file

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { MatCardModule } from '@angular/material/Card';
import { MatInputModule } from '@angular/material/input';



import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { PostCreateComponent } from './posts/post-create/post-create.component';
import { from } from 'rxjs';


@NgModule({
  declarations: [
    AppComponent,
    PostCreateComponent,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    BrowserAnimationsModule,
    MatInputModule,
    MatCardModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

package.json

{
  "name": "mean-course",
  "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": "~9.1.0",
    "@angular/cdk": "^9.2.0",
    "@angular/common": "~9.1.0",
    "@angular/compiler": "~9.1.0",
    "@angular/core": "~9.1.0",
    "@angular/forms": "~9.1.0",
    "@angular/material": "^9.2.0",
    "@angular/platform-browser": "~9.1.0",
    "@angular/platform-browser-dynamic": "~9.1.0",
    "@angular/router": "~9.1.0",
    "rxjs": "~6.5.4",
    "tslib": "^1.10.0",
    "zone.js": "~0.10.2"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.901.0",
    "@angular/cli": "~9.1.0",
    "@angular/compiler-cli": "~9.1.0",
    "@angular/language-service": "~9.1.0",
    "@types/node": "^12.11.1",
    "@types/jasmine": "~3.5.0",
    "@types/jasminewd2": "~2.0.3",
    "codelyzer": "^5.1.2",
    "jasmine-core": "~3.5.0",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~4.4.1",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage-istanbul-reporter": "~2.1.0",
    "karma-jasmine": "~3.0.1",
    "karma-jasmine-html-reporter": "^1.4.2",
    "protractor": "~5.4.3",
    "ts-node": "~8.3.0",
    "tslint": "~6.1.0",
    "typescript": "~3.8.3"
  }
}
{
  "name": "mean-course",
  "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": "~9.1.0",
    "@angular/cdk": "^9.2.0",
    "@angular/common": "~9.1.0",
    "@angular/compiler": "~9.1.0",
    "@angular/core": "~9.1.0",
    "@angular/forms": "~9.1.0",
    "@angular/material": "^9.2.0",
    "@angular/platform-browser": "~9.1.0",
    "@angular/platform-browser-dynamic": "~9.1.0",
    "@angular/router": "~9.1.0",
    "rxjs": "~6.5.4",
    "tslib": "^1.10.0",
    "zone.js": "~0.10.2"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.901.0",
    "@angular/cli": "~9.1.0",
    "@angular/compiler-cli": "~9.1.0",
    "@angular/language-service": "~9.1.0",
    "@types/node": "^12.11.1",
    "@types/jasmine": "~3.5.0",
    "@types/jasminewd2": "~2.0.3",
    "codelyzer": "^5.1.2",
    "jasmine-core": "~3.5.0",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~4.4.1",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage-istanbul-reporter": "~2.1.0",
    "karma-jasmine": "~3.0.1",
    "karma-jasmine-html-reporter": "^1.4.2",
    "protractor": "~5.4.3",
    "ts-node": "~8.3.0",
    "tslint": "~6.1.0",
    "typescript": "~3.8.3"
  }
}

If I correctly understand I'm missing somehow / somewhere the definition of the mat-... tags but I don't know where I need to put what kind of definition? Can someone enlighten me a little bit?

Answer 1

You must add MatFormFieldModule to AppModule

import { MatFormFieldModule } from '@angular/material/form-field';
...
@NgModule({
    imports: [
        ...
        MatFormFieldModule
    ]
})

Answer 2

I know it's late reply but I had same issue it got solved just by installing jquery and adding it in script. You need to do following steps:

1. typo mistake it will be "mat-form-field" instead of "mat-mat-form-field".
2. npm install jquery --save run this command.
3. add jquery "./node_modules/jquery/dist/jquery.min.js" path, to angular.json file under "scripts":[].