Sequencing API Calls: A Guide on Making Sequential API Requests

Question

Sequencing API Calls: A Guide on Making Sequential API Requests

Currently, I am working on mastering RxJS. Within my project, there are 3 API calls that need to be made. Specifically, I must execute the 2nd API call and then pass its data as a parameter to the 3rd API call. My attempt at achieving this functionality is outlined below:

    checkPermission(permissionName: string): Observable<boolean> {
    this.check(this.p1)
      .pipe(
        switchMap(res => {
          const shouldCheck = res.Value;
          if (shouldCheck.toLowerCase() === 'true') {
            return this.checkPermission(permissionName).pipe(
              map(result => {
               
                return result;
              })
            );
          } else return of(true);
        })
      )
      .subscribe(permission => {
       
      });       
    }

Unfortunately, I encountered a syntax error while testing this implementation.

angular typescript rxjs

Answer 1

Answer №1

The code snippet you provided may be a bit hard to follow, but I will attempt to improve its readability:

  validatePermission(permissionName: string): Observable<boolean> {
    return this.checkSetting(this.p1).pipe(
      map((res) => res.SysConfig.Value.toLowerCase() === 'true'),
      switchMap((shouldValidate) =>
        iif(
          () => shouldValidate,
          this.checkAuthorization(this.p2).pipe(
            switchMap((data) =>
              this.validatePermissionStatus(permissionName, data.SysConfig.Value)
            ),
            // assuming that the authorization status is boolean
            map((res) => res.authorized)
          ),
          of(true)
        )
      )
    );
  }

If you intend on returning an Observable<boolean>, it's recommended to avoid using subscribe within this method. You can subscribe to the observable at the point of usage like so:

this.authService.validatePermission(accessControl).subscribe(hasAccess => {
  console.log(`User ${hasAccess ? 'has' : 'does not have'} access control for ${permission}`);
});

Answer 2

The code snippet you provided may be a bit hard to follow, but I will attempt to improve its readability:

  validatePermission(permissionName: string): Observable<boolean> {
    return this.checkSetting(this.p1).pipe(
      map((res) => res.SysConfig.Value.toLowerCase() === 'true'),
      switchMap((shouldValidate) =>
        iif(
          () => shouldValidate,
          this.checkAuthorization(this.p2).pipe(
            switchMap((data) =>
              this.validatePermissionStatus(permissionName, data.SysConfig.Value)
            ),
            // assuming that the authorization status is boolean
            map((res) => res.authorized)
          ),
          of(true)
        )
      )
    );
  }

If you intend on returning an Observable<boolean>, it's recommended to avoid using subscribe within this method. You can subscribe to the observable at the point of usage like so:

this.authService.validatePermission(accessControl).subscribe(hasAccess => {
  console.log(`User ${hasAccess ? 'has' : 'does not have'} access control for ${permission}`);
});

Answer 3

Answer №2

Feel free to give this a shot, I haven't personally verified it.

   verifyPermission(permission: string): Observable<boolean> {
      return this.verifyCompanySettingForPermission(this.p1)
          .pipe(
            switchMap(result => this.checkUserPermissionAPI(result, permission)),
            tap(perm => this.$permissionSub.next(perm)),
            switchMap(_=> this.$permissionSub.asObservable())
          )
     }
    
    checkUserPermissionAPI(result :any, permission: string): Observable<any>{
        const shouldVerify = result.SysConfig.Value;
        if (shouldVerify.toLowerCase() === 'true') {
           return this.processUserPermissionAPI(permission);
        }
        return of(true);
    }

  processUserPermissionAPI(permission: string) :Observable<boolean>{
    return this.verifyCompanySettingForPermission(this.p2).pipe(
       switchMap(data => 
        this.validatePermission(permission, data.SysConfig.Value).pipe(
              map(( {granted})=>granted)
            )
        )
     );
  }

Answer 4

Feel free to give this a shot, I haven't personally verified it.

   verifyPermission(permission: string): Observable<boolean> {
      return this.verifyCompanySettingForPermission(this.p1)
          .pipe(
            switchMap(result => this.checkUserPermissionAPI(result, permission)),
            tap(perm => this.$permissionSub.next(perm)),
            switchMap(_=> this.$permissionSub.asObservable())
          )
     }
    
    checkUserPermissionAPI(result :any, permission: string): Observable<any>{
        const shouldVerify = result.SysConfig.Value;
        if (shouldVerify.toLowerCase() === 'true') {
           return this.processUserPermissionAPI(permission);
        }
        return of(true);
    }

  processUserPermissionAPI(permission: string) :Observable<boolean>{
    return this.verifyCompanySettingForPermission(this.p2).pipe(
       switchMap(data => 
        this.validatePermission(permission, data.SysConfig.Value).pipe(
              map(( {granted})=>granted)
            )
        )
     );
  }

Answer 5

Answer №3

To optimize your code, make sure to utilize the switchMap operator in the correct sequence:

.pipe(
    switchMap(() => {
        return this.someFunctionThatReturnsObservable();
    }),
    // By doing this, you can access the data returned in the previous step through the 'data' variable
    switchMap((data) => {
        return this.someOtherRequest(data.param1, data.param2).pipe(
            map(result => {
              return result.permission;
            })
        );
    })
)

It is important to remember that when using rxjs operators, they should be placed one after another within the pipe separated by commas. The issue lies in attempting to insert code without the appropriate operators within the pipe. These lines are causing a problem:

return this.permission(this.p2).pipe(
    const shouldEncrypt = res.SysConfig.Value;

The intention behind this section is not entirely clear, but it seems like there is an attempt to conditionally return a request or an empty observable. To achieve this, ensure that you include the necessary operator before inserting the code mentioned above.

Answer 6

To optimize your code, make sure to utilize the switchMap operator in the correct sequence:

.pipe(
    switchMap(() => {
        return this.someFunctionThatReturnsObservable();
    }),
    // By doing this, you can access the data returned in the previous step through the 'data' variable
    switchMap((data) => {
        return this.someOtherRequest(data.param1, data.param2).pipe(
            map(result => {
              return result.permission;
            })
        );
    })
)

It is important to remember that when using rxjs operators, they should be placed one after another within the pipe separated by commas. The issue lies in attempting to insert code without the appropriate operators within the pipe. These lines are causing a problem:

return this.permission(this.p2).pipe(
    const shouldEncrypt = res.SysConfig.Value;

The intention behind this section is not entirely clear, but it seems like there is an attempt to conditionally return a request or an empty observable. To achieve this, ensure that you include the necessary operator before inserting the code mentioned above.

Sequencing API Calls: A Guide on Making Sequential API Requests

Answer №1

Answer №2

Answer №3

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