如何从此 firebase 返回的结果访问电子邮件的值?

How can I acces the value of email from this firebase returned result?

我正在使用 ionic2 和 firebase。使用 Angularfire2,我通过以下代码检索用户:如果我尝试这样的事情:

console.log(user.email);

我不确定

signup_with_username(email: string, password: string) {

    this.email = email;

    const user_from_db = this.afDb.list('/users', {
        query: {
            orderByChild: 'email',
            equalTo: this.email,
            limitTo: 1,
        }
    });

    user_from_db.subscribe(user => console.log(user));

}

替换下面的

user_from_db.subscribe(user => console.log(user));

user_from_db.subscribe(user => console.log(user[0].email));