Prevent Closing Angular Material Dialog by Clicking Outside (Angular 4+)

• Angular Material provides a built-in MatDialog component for creating modal dialogs.
• These dialogs typically have a dark backdrop behind them, making the dialog the main focus on the screen.
• By default, users can close the dialog by:
  • Pressing the Escape (Esc) key.
  • Clicking the close icon in the dialog header (if present).
  • Clicking anywhere outside the dialog itself (on the backdrop).

Disabling Click Outside to Close:

There are two main approaches to achieve this:

1. Configuration During Dialog Opening:

   • When opening the dialog using the MatDialog.open() method, you can pass a configuration object with the disableClose property set to true. This disables both Esc key and backdrop click closing:

   import { MatDialog, MatDialogConfig } from '@angular/material/dialog';
   
   export class MyComponent {
     constructor(private dialog: MatDialog) {}
   
     openDialog() {
       const config: MatDialogConfig = {
         disableClose: true
       };
   
       this.dialog.open(MyDialogComponent, config);
     }
   }
   

2. Handling Backdrop Click in Dialog Component:

   • Inject the MatDialogRef service into your dialog component.
   • Set the disableClose property of MatDialogRef to true to prevent the default closing behavior.
   • Subscribe to the backdropClick() observable of MatDialogRef. This observable emits an event when the backdrop is clicked.
   • Inside the subscription, manually close the dialog using the close() method of MatDialogRef. This allows you to potentially perform custom actions before closing.

   import { MatDialogRef } from '@angular/material/dialog';
   
   export class MyDialogComponent {
     constructor(private dialogRef: MatDialogRef<MyDialogComponent>) {
       this.dialogRef.disableClose = true;
   
       this.dialogRef.backdropClick().subscribe(() => {
         // Optional: Perform actions before closing
         this.dialogRef.close();
       });
     }
   }
   

Choosing the Right Approach:

• If you simply want to prevent closing by both Esc key and backdrop click, the first approach (configuration) is more concise.
• If you need to execute custom logic before closing the dialog in response to a backdrop click, the second approach is more suitable.

import { MatDialog, MatDialogConfig } from '@angular/material/dialog';

export class MyComponent {
  constructor(private dialog: MatDialog) {}

  openDialog() {
    const config: MatDialogConfig = {
      disableClose: true // This disables both Esc key and backdrop click closing
    };

    this.dialog.open(MyDialogComponent, config);
  }
}

In this example, the disableClose property is set to true within the MatDialogConfig object passed to the dialog.open() method. This configuration applies globally to the opened dialog, preventing closing by both the Esc key and clicking outside.

import { MatDialogRef } from '@angular/material/dialog';

export class MyDialogComponent {
  constructor(private dialogRef: MatDialogRef<MyDialogComponent>) {
    this.dialogRef.disableClose = true; // Prevent default closing behavior

    this.dialogRef.backdropClick().subscribe(() => {
      console.log('Backdrop clicked!'); // Optional: Perform custom actions before closing
      this.dialogRef.close(); // Manually close the dialog
    });
  }
}

Here, the disableClose property is set to true on the MatDialogRef instance within the dialog component's constructor. This prevents the default closing behavior.

Next, the backdropClick() observable of MatDialogRef is subscribed to. This observable emits an event whenever the backdrop is clicked. Inside the subscription, you can optionally perform custom actions (like logging a message in this example) before manually closing the dialog using dialogRef.close().

• Use Example 1 if you simply want to prevent closing by both Esc key and backdrop click.
• Use Example 2 if you need to execute custom actions before closing the dialog in response to a backdrop click.

• Global Configuration (Advanced):

  While not directly an alternate method, you can potentially set a global default for disableClose using Angular providers. This approach requires caution as it can affect all dialogs in your application. Here's an example (use with discretion):

  import { MAT_DIALOG_DEFAULT_OPTIONS } from '@angular/material/dialog';
  
  @NgModule({
    providers: [
      { provide: MAT_DIALOG_DEFAULT_OPTIONS, useValue: { disableClose: true } }
    ]
  })
  export class AppModule { }
  

  In this case, all dialogs opened using MatDialog.open() would have disableClose set to true by default, unless explicitly overridden during dialog opening with a configuration object.

Important Considerations:

• Accessibility: Disabling closing by clicking outside can hinder accessibility for users who might rely on it. Ensure you provide a clear way for users to close the dialog through other means, such as a close button or keyboard shortcuts.
• User Experience: Consider if preventing outside click closing aligns with the expected user experience. In some cases, users might find it frustrating if they can't close the dialog by clicking the background.
• Customizable Closing Behavior: While these methods prevent closing by clicking outside, you might still want to allow closing through other interactions (like buttons or specific key presses). You can achieve this by handling those events within your dialog component and calling dialogRef.close() accordingly.