Angular Material - Can't resolve '@angular/material/theming'

Question

I have followed the official guide and created a app-theme.scss with the following content:

@import '~@angular/material/theming';    
@include mat-core();    
$candy-app-primary: mat-palette($mat-indigo);
$candy-app-accent:  mat-palette($mat-pink, A200, A100, A400);    
$candy-app-warn:    mat-palette($mat-red);    
$candy-app-theme: mat-light-theme($candy-app-primary, $candy-app-accent, $candy-app-warn);    
@include angular-material-theme($candy-app-theme);

Content of styles.css:

@import './app-theme.scss';

However, I always get the following error during compilation: Module not found: Error: Can't resolve '@angular/material/theming'. What must I do to make it work?

Answer 1

Solved:

The Angular Material 2 documentation assumes you are using sass style-sheets by default. This is never clearly communicated or explained. The steps listed below can be used to resolve this issue.

1. Rename styles.css to styles.scss and set its content to @import './app-theme';
2. In angular-cli.json, change styles: ["styles.css"] to styles: ["styles.scss"]
3. Restart npm

Answer 2

Angular 6+ --- Get all in one command

In Angular 6+, you simply need to install angular-material like

ng add @angular/material

What this command does? well see here

1. Installs angular material, cdk, animations
2. Adds references to the app.module.ts
3. Adds material-icons' reference to the index.html
4. It asks you to select the theme of your choice and adds reference to the angular.json (if theme does not work, import it in styles.css/styles.scss as described below)

but in previous versions, you were doing these steps manually

Angular 5

Using Angular5+, one or both import methods will work for you

@import "@angular/material/prebuilt-themes/indigo-pink.css";

@import "~@angular/material/prebuilt-themes/indigo-pink.css"; // in official docs

Answer 3

Try this,

1. Change your theme file name to _app-theme.scss

2. Change your styles.css to styles.scss

3. Import your theme into the styles.scss file like:

@import './path/to/your/theme/app-theme'; // You dont need the underscore and file extention here

4. You dont need to include your theme file in angular-cli.json styles: []

Answer 4

Are you sure, that you have installed angular materials in this project ? Sometimes you can copy only the content of web page, but without node_modules folder and in that case compiler can't find the path 'node_modules/@angular/material/theming'.

Just try this command and you will see.

npm install --save @angular/material @angular/cdk

It could help.

Answer 5

According to the official guide you provided, you should not be importing your theme file into your styles.css file, instead, you should put it into the styles array of your angular-cli.json file, it should be something close to this:

styles: [
  "app-theme.scss",
  "styles.css"
]

Answer 6

1. Check this path ERROR in ./node_modules/@angular/material/prebuilt-themes/indigo-pink.css while you install any other module or library. In my case I installed Angular Syncfusion scheduler

2. A new import statement gets added in the above path so what you have to do is just cut paste that import statement in style.css because it should it generally be there

3. And while doing this process, the Angular material folder or Angular Syncfusion folder may also get deleted from node_modules, so make sure you type the command npm install so that npm can install all the dependencies mentioned in package.json