Restoring previous configuration in Ionic2 from the resume() lifecycle method

Question

Restoring previous configuration in Ionic2 from the resume() lifecycle method

Encountering an issue with my ionic2 application where I save the last state in local storage when the app goes to the background. Upon resuming, it checks for the value of lastState in local storage and pushes that state if a value exists. The specific error being received is:

ERROR Error: Uncaught (in promise): invalid link: <StateName>
at c (file:///android_asset/www/build/polyfills.js:3:13190)
at Object.reject (file:///android_asset/www/build/polyfills.js:3:12546)
at NavControllerBase._fireError (file:///android_asset/www/build/main.js:44942:16)
at NavControllerBase._failed (file:///android_asset/www/build/main.js:44930:14)
at file:///android_asset/www/build/main.js:44985:59
at t.invoke (file:///android_asset/www/build/polyfills.js:3:8971)
at Object.onInvoke (file:///android_asset/www/build/main.js:4407:37)
at t.invoke (file:///android_asset/www/build/polyfills.js:3:8911)
at r.run (file:///android_asset/www/build/polyfills.js:3:4140)
at file:///android_asset/www/build/polyfills.js:3:13731

The application functions properly despite this error. Can someone shed light on the reason for this behavior?

Code `app.component.ts`

     this.platform.pause.subscribe(() => {
            console.log('[INFO] App Paused.');
            localStorage.setItem("lastState", this.nav.last().name);
     })

resume() method

this.platform.resume.subscribe(() => {
            console.log('[INFO] App resumed);           
            if(null != localStorage.getItem("lastState") && localStorage.getItem("lastState") != undefined) {
                this.nav.push(localStorage.getItem("lastState"));
            }
        });

Note: All component names have been added to app.module.ts

angular typescript ionic2

Answer 1

Answer №1

It appears that the issue lies in attempting to push a string instead of an imported module from the page, which will only be successful if Lazy Loading is being used in your modules. You have two options:

Implement Lazy loading for all your page components so you can utilize them on NavController as a string rather than the imported module name.
Import all your pages, create an object with them, and use
```
this.nav.push(this.yourCreatedObject[localStorage.getItem("lastState")]);
```
to access the parameter in your object containing the module. This approach may or may not work, but it's worth trying if you wish to avoid wasting time with lazy loading.

A point to consider:

When the app enters a paused state, it will remain on the current page without needing to save the page and then push it again. There is no need to return to the root or lose the navigation stack upon pausing, as pushing the same page again could result in a poor user experience. It is advisable to refrain from doing this.

PS: There seems to be a missing ' in your console.log() within the resume method.

EDIT

If you wish to restart the app, simply navigate to the root page of your application by using this.nav.popToRoot(). This way, there is no need to save the state or switch to lazy loading.

EDIT 2

To restart after 15 minutes, you will need a timer and a shift to lazy loading architecture.

You can proceed as follows:

public timer: any;
public counter: number = 0; // add these two variables to the scope of your class in app.components

this.platform.pause.subscribe(() => {
  localStorage.setItem("lastState", this.nav.last().name);
  this.timer = setInterval(()=>{
    this.counter += 50;
  }, 50);
});

this.platform.resume.subscribe(() => {
  const lastState = localStorage.getItem("lastState"); // Retrieve the latest state, as there will always be one because the app always pauses
  clearInterval(this.timer); // Clear the interval
  if(this.counter < 900000) // If it's under the required time (900000 == 15 min)
    this.nav.setRoot(lastState);
  else
    this.nav.popToRoot();
});

This approach will only function if the app is paused but not terminated. If you desire the same behavior even if the user kills and restarts the app, additional challenges will arise, such as determining when the app was last opened and whether it falls within the 15-minute timeframe.

Answer 2

It appears that the issue lies in attempting to push a string instead of an imported module from the page, which will only be successful if Lazy Loading is being used in your modules. You have two options:

Implement Lazy loading for all your page components so you can utilize them on NavController as a string rather than the imported module name.
Import all your pages, create an object with them, and use
```
this.nav.push(this.yourCreatedObject[localStorage.getItem("lastState")]);
```
to access the parameter in your object containing the module. This approach may or may not work, but it's worth trying if you wish to avoid wasting time with lazy loading.

A point to consider:

When the app enters a paused state, it will remain on the current page without needing to save the page and then push it again. There is no need to return to the root or lose the navigation stack upon pausing, as pushing the same page again could result in a poor user experience. It is advisable to refrain from doing this.

PS: There seems to be a missing ' in your console.log() within the resume method.

EDIT

If you wish to restart the app, simply navigate to the root page of your application by using this.nav.popToRoot(). This way, there is no need to save the state or switch to lazy loading.

EDIT 2

To restart after 15 minutes, you will need a timer and a shift to lazy loading architecture.

You can proceed as follows:

public timer: any;
public counter: number = 0; // add these two variables to the scope of your class in app.components

this.platform.pause.subscribe(() => {
  localStorage.setItem("lastState", this.nav.last().name);
  this.timer = setInterval(()=>{
    this.counter += 50;
  }, 50);
});

this.platform.resume.subscribe(() => {
  const lastState = localStorage.getItem("lastState"); // Retrieve the latest state, as there will always be one because the app always pauses
  clearInterval(this.timer); // Clear the interval
  if(this.counter < 900000) // If it's under the required time (900000 == 15 min)
    this.nav.setRoot(lastState);
  else
    this.nav.popToRoot();
});

This approach will only function if the app is paused but not terminated. If you desire the same behavior even if the user kills and restarts the app, additional challenges will arise, such as determining when the app was last opened and whether it falls within the 15-minute timeframe.

Restoring previous configuration in Ionic2 from the resume() lifecycle method

Code `app.component.ts`

resume() method

Answer №1

EDIT

EDIT 2

Similar questions

Token authentication in Angular 4

The error message "Property 'showUserDropdown' is not found on type '{}'.ts" indicates that the specified property is not present in the defined

The State of NgRX Entity is encountering undefined IDs

What are some strategies for validating form fields in the Back-End and displaying them in Angular7?

What is the best way to utilize a single component for validating two other components?

Arrange text and a button side by side in a table cell using an Angular directive and an HTML template

Having difficulty resolving rxjs issue

How can a singleton object be referenced or injected into a constant in Angular?

Having trouble with vscode compiling the typescript file?

What is the most efficient way to execute useEffect when only one specific dependency changes among multiple dependencies?

Having trouble retrieving a dynamic name with Formcontrol error?

Parsing error encountered while trying to handle an unexpected token at line 214, character 33. It appears that an appropriate loader is missing to process this particular file type

An error occurred with the datepicker: Unable to connect to 'bsValue' as it is not recognized as a property of 'input'

Enhanced assistance for optional chaining operator available in Visual Studio Code

Type definition for Vuex store functionality

Propositional Properties within the Interface

Error message: Conflicting type declarations across multiple files

Steps for importing jQuery typings into TypeScript:1. First, install the jQuery

What kind of ng-template is used for enforcing strict typing in Angular?

Encountered an error while attempting to run the org.apache.maven.plugins:maven-jar-plugin:2.6:jar goal

Restoring previous configuration in Ionic2 from the resume() lifecycle method

Code app.component.ts

resume() method

Answer №1

EDIT

EDIT 2

Similar questions

Token authentication in Angular 4

The error message "Property 'showUserDropdown' is not found on type '{}'.ts" indicates that the specified property is not present in the defined

The State of NgRX Entity is encountering undefined IDs

What are some strategies for validating form fields in the Back-End and displaying them in Angular7?

What is the best way to utilize a single component for validating two other components?

Arrange text and a button side by side in a table cell using an Angular directive and an HTML template

Having difficulty resolving rxjs issue

How can a singleton object be referenced or injected into a constant in Angular?

Having trouble with vscode compiling the typescript file?

What is the most efficient way to execute useEffect when only one specific dependency changes among multiple dependencies?

Having trouble retrieving a dynamic name with Formcontrol error?

Parsing error encountered while trying to handle an unexpected token at line 214, character 33. It appears that an appropriate loader is missing to process this particular file type

An error occurred with the datepicker: Unable to connect to 'bsValue' as it is not recognized as a property of 'input'

Enhanced assistance for optional chaining operator available in Visual Studio Code

Type definition for Vuex store functionality

Propositional Properties within the Interface

Error message: Conflicting type declarations across multiple files

Steps for importing jQuery typings into TypeScript:1. First, install the jQuery

What kind of ng-template is used for enforcing strict typing in Angular?

Encountered an error while attempting to run the org.apache.maven.plugins:maven-jar-plugin:2.6:jar goal

Code `app.component.ts`