I have two servince.ts function
getSessions(): Promise<UserSessionInterface[]> {
    return this.sessioAPI.find()
        .toPromise()
        .then(response => response as UserSessionInterface);
}
getUserDetails(id: string): Promise<any> {
    return this.sessioAPI.getUser(id)
        .toPromise()
        .then(response => response.firstName + ' ' + response.lastName)
        .catch(this.handleError);
}
I call them on component.ts like this
getSessions() {
    this._service.getSessions()
        .then(result => {
            this.results = result;
        });
}
getUserDetails(id?: string) {
    return this._service.getUserDetails(id)
        .then(result => {
            console.log('Inside result : ' + result);
            this.userName = result;
        });
} 
getUserName(id: string) {
    return this.getUserDetails(id);
}
I know I can do it with single request inside of component and assign the result to global variable.
But, what I want is to call getUserName function dynamically inside of *ngFor, and return the result of Promise as string directly.
Thanks in advance.