CODEWITHSUNDEEP
javascriptangularjspromise
Elias
Elias

Reputation: 802

Understanding of the promises chaining: 'then()' get's undefined parameter as the result

I started to work deeply with promises, and need your help to understand why this code doesn't work as expected.

Here is what I need:

After successful profile retrieving the code should log out ('success getting Profile!') which it does, and return true as result, that should be passed to the next then() element. But instead of true, I get undefined as the result.

  public verifyAuth(): angular.IPromise<boolean> {
    let promise: ng.IPromise<boolean> = this._Token.getIdToken()
      .then((idToken) => {
        if (!idToken) {
          return false;
        }
        else if (this._Profile.isEmpty()) {
          promise = this.retrieveProfileInfo()
            .then(() => {
              this._$log.log('success getting Profile!');
              return true;
            });
        } else {
          return true;
        }
      })
      .catch((error) => {
        this._Token.clearToken();
        this._$log.error(error);
        return false;
      });

    return promise;
  }

enter image description here

Upvotes: 1

Views: 118

Answers (1)

dfsq
dfsq

Reputation: 193261

You are returning the first promise object before your reassign it later in the success then block. You don't need to do it just use chaining like this:

public verifyAuth(): angular.IPromise<boolean> {
  let promise: ng.IPromise<boolean> = this._Token.getIdToken()
    .then((idToken) => {
      if (!idToken) {
        return false;
      }
      else if (this._Profile.isEmpty()) {
        return this.retrieveProfileInfo()
          .then(() => {
            this._$log.log('success getting Profile!');
            return true;
          });
      } else {
        return true;
      }
    })
    .catch((error) => {
      this._Token.clearToken();
      this._$log.error(error);
      return false;
    });

  return promise;
}

Note, how you simply return this.retrieveProfileInfo() which becomes new promise automatically.

Upvotes: 2

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