feat: add ability for routing integrations to not cache views

Bug Report

Ionic version:

[x] 4.x

Current behavior:

It looks like the back button does not show up in some cases when it should. This happens if one page gets opened a second time.

Possibly pages get initialized without ‘can-go-back’ and this does not get updated.

Wrong behavior: My app opens a “list page” which can open a “detail page” which can open the “list page” with other query params again. This “list page” does not show an ionic-back-button.

Expected behavior:

I would expect the ionic-back-button to show on the last “list page” and take me back to the “detail page” and from there another ionic-back-button to the first “list page”.

Steps to reproduce:

• Start app on home page
• Click on button on homepage at the bottom “LIST”
• Navigated to ListPage
• Click on “Item 1”
• Navigated to Homepage -> There is no back button

If I use the list page from menu, the back-button will show on the home page. But if I go to the list page again from there, the button will disappear as well.

Related code:

This is my test case.

Other information:

Ionic info:

New menu template

Ionic:

   Ionic CLI                     : 5.4.1 (/Users/gedysintraware/.nvm/versions/node/v10.13.0/lib/node_modules/ionic)
   Ionic Framework               : @ionic/angular 4.10.0
   @angular-devkit/build-angular : 0.801.3
   @angular-devkit/schematics    : 8.1.3
   @angular/cli                  : 8.1.3
   @ionic/angular-toolkit        : 2.0.0

Utility:

   cordova-res : 0.6.0 
   native-run  : 0.2.8 

System:

   NodeJS : v10.13.0 (/Users/gedysintraware/.nvm/versions/node/v10.13.0/bin/node)
   npm    : 6.4.1
   OS     : macOS Mojave

[marcoromag]

same happens with React apps

[liamdebeasi]

Thanks for the issue. By default, all of our routing integrations will re-use existing views if they match the same URL. For example:

/a --> /b --> /a would re-use the rendered view for /a and ion-back-button would not appear since it is on the root view.

While this is working as intended, I can understand that this may not be expected or desirable in some situations. Changing this would be a breaking change that we can look into, or we can look into making this an opt-in feature. Either way there is certainly going to need to be some discussion about how to implement this.

For anyone who is running into this scenario: Would you be able to provide a use case and a code sample that can help us understand how this behavior affects your applications? Thanks!