What could be causing the conditional div to malfunction in Angular?

There are three conditional div elements on a page, each meant to be displayed based on specific conditions.

<div *ngIf="isAvailable=='true'">
    <form>
            <div class="form-group">
                    <label for="Admin">Deployment Admin</label>
                    <input type="text" class="form-control" id="name" name="name" aria-describedby="name" [(ngModel)]="NewDeployAdmin.name">
                  </div>
            <div class="form-group">
              <label for="exampleInputEmail1">Email address</label>
              <input type="email" class="form-control" id="email" name="email" aria-describedby="email" placeholder="Enter email" [(ngModel)]="NewDeployAdmin.email">

            </div>
            <div class="form-group">
              <label for="exampleInputPassword">Password</label>
              <input type="password" class="form-control" id="paswsword" name="password" placeholder="Password" placeholder="Enter al least 6 character" [(ngModel)]="NewDeployAdmin.password">
            </div>
            <button type="submit" class="btn btn-primary" (click)="fnCreateDeployAdmin()">Submit</button>
    </form>   
</div>

<div *ngIf="isAvailable=='false'">
<button  type="submit" class="btn btn-warning" (click)="fnDisableAccount()">Disable Account</button> | <button  type="submit" class="btn btn-primary" (click)="fnUpdateDeployAdmin()">Reset Credential</button>
</div>

The .ts file handles the setting of the isAvailable value under different conditions to control the display of corresponding div elements. However, there seems to be an issue with this logic not working as expected.

The code snippet below shows how the isAvailable value is being set:

isDeploymentAdminAvailable(deployment){
  let customQuery = {
    equalTo: this.selectedDeploy.key
  }

  this.authService.fnGetDataUsingCustomQuery(FirebaseDb.firebasedeploymentAdminTable, customQuery).subscribe(
    (rec: any) => {
      rec.forEach((reccord: any) => {
        reccord.key = reccord.$key;
      });
      this.deployAdminData = JSON.parse(JSON.stringify(rec));

    });

  if(this.deployAdminData!=null && Object.keys(this.deployAdminData).length>0){
    return "true";

  }

  return "false";

}

Here is where the isDeploymentAdminAvailable method is called to determine the isAvailable status:

deploymentOnClick($event, deployment){ 

    this.isAvailable = 'None';

    this.selectedDeploy = deployment;

     this.isAvailable = this.isDeploymentAdminAvailable(deployment);
}

Answer №1

You have to make sure that the "true" and "false" values are treated as boolean types by removing the quotes around them and setting the type of isAvailable to boolean. Use *ngIf to compare isAvailable or !isAvailble.

Your code has multiple issues. It's important to have determinate return statements in single-threaded Javascript, such as using if followed by else. Avoid using terms like true, false, or None for conditional statements if more than two options are possible.

Ensure parameter typing in your TypeScript code. All parameters should be explicitly defined, not left as any.

Avoid unused variables like deployment passed into functions. Always use strict equality operators === and !== in JavaScript.

If you're facing rendering issues with the divs, check if isAvailable is properly configured as a boolean. Use console.log statements to debug conditions and behavior.

The problem may lie in asynchronous code execution where Firebase data is not returned before being checked. Separate the validation logic into a function called after subscribing to data retrieval.


this.authService.fnGetDataUsingCustomQuery(FirebaseDb.firebasedeploymentAdminTable, customQuery).subscribe(
    (rec: any) => {
        rec.forEach((reccord: any) => {
            reccord.key = reccord.$key;
        });
        this.deployAdminData = JSON.parse(JSON.stringify(rec));
        this.isAvailable = this.yourFunctionName(deployAdminData);
    });

yourFunctionName(deployAdminData: any) {
    if(deployAdminData !== null && Object.keys(deployAdminData).length > 0) {
        return true;    
    } else { 
        return false; 
    }  
}

Update the method:


deploymentOnClick($event, deployment){ 
//this.isAvailable = 'None';
this.selectedDeploy = deployment;
this.isDeploymentAdminAvailable(deployment);
}

By making these changes and following best practices, you can utilize *ngIf="isAvailable" in your code seamlessly.

Answer №2

The main issue with the visibility control of your div using the isAvailable variable has already been explained - the value needs to be set within the subscribe function.

However, changing the type of this flag to Boolean seems to break the functionality of the application.

Based on my understanding, the app's logic dictates that both div elements should remain hidden (isAvailable === 'None') before data is fetched. After the fetch, one of the divs should be displayed based on the returned value.


Improving code according to Angular best practices

You may consider moving the code in isDeploymentAdminAvailable into a separate service called authService.

This approach offers several advantages:

  • All fetching logic is centralized
  • Testing becomes more streamlined
  • Reduces dependency on Firebase within the component
  • Exposes data and the isAvailable property as Observables

Using Observable Naming Conventions

It's recommended to add a suffix like $ to observable variables to indicate that they require an async pipe in the template or need to be subscribed to in the TypeScript code.


Benefits of Using Observable Variables

By utilizing observable variables and the async pipe in templates, your app can render the page even before Firebase returns data. Any updates from Firebase will automatically reflect in the view without needing manual refreshes.

One point that's unclear is the relationship between NewDeployAdmin and this.deployAdminData. Depending on their connection, you might need to use a subscribe() or the async pipe for appropriate handling.


Code Snippet from authService.ts

@Injectable()
export class AuthService {

  public deployAdminData$ = new BehaviorSubject({});
  public isAvailable$ = new BehaviorSubject('None');  

  private fnGetDataUsingCustomQuery(...) {
    // Implementation
  }

  public isDeploymentAdminAvailable(key) {
    let customQuery = {
      equalTo: key
    }
    this.fnGetDataUsingCustomQuery(FirebaseDb.firebasedeploymentAdminTable, customQuery)
      .subscribe(rec => {
        // Update logic here
      });
}

Template Code from myComponent.html

<div *ngIf="(isAvailable$ | async)=='true'">
  <form>
    <!-- Form fields for deployment admin -->
  </form>   
</div>

<div *ngIf="(isAvailable$ | async)=='false'">
  <button type="submit" class="btn btn-warning">Disable Account</button>
  <button type="submit" class="btn btn-primary">Reset Credential</button>
</div>

Snippet from myComponent.ts

// Observable pipeline setup to monitor database changes.
private isAvailable$ = this.authService.isAvailable$;
private this.deployAdminData$ = this.authService.this.deployAdminData$;

isDeploymentAdminAvailable(deployment) {
  this.authService.isDeploymentAdminAvailable(this.selectedDeploy.key)
}

Answer №3

One efficient way to optimize your template is by directly passing the value isAvailable instead of comparing and using expressions.

<div *ngIf="isAvailable">
   ...
</div>    
<div *ngIf="!isAvailable">
   ...
</div>

Implementing this change can greatly improve performance. Give it a try!

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