来自Promise React Native的结果

Question

Here is me connexion method:

export  function connexionUser(email, password) {

    result = firebase.auth().signInWithEmailAndPassword(email, password)
        .then((res) => {
            console.log("res: ", res)
            return true;
        })
        .catch(function (error) {
            return false;
        });
        return result;
};

Here my method in index.js:

login = () => {

    const { email, password } = this.state;
    var result = connexionUser(email, password);
    console.log("result");
    console.log(result);
    if (result == true) {
        this.props.navigation.navigate('Favorites');
    }
}

Problem : I would like to get the result of "connexionUser()" in my index.js to be able to manage the navigation or something else. But my result isn't true or false:

result
A {
  "a": 0,
  "b": null,
  "c": A {
    "a": 0,
    "b": qb {
      "a": [Circular],
      "b": [Function anonymous],
      "c": false,
      "f": null,
      "g": [Function anonymous],
      "next": null,
    },
    "c": A {
      "a": 0,
      "b": qb {
        .....
        .....and more

PS : i am a beginner in React native.

Answer 1

You can always try to throw in a console.log to see what the output of the result is. If you're having trouble debugging with React Native, the docs on debugging are really helpful.

As it stands, your registerUser will return undefined since you aren't actually returning the result. I imagine you're trying to return result in your then statement, but the then statement should be receiving the results of your firebase function and returning those results. I'd recommend reading up a bit about Promises for clarification on how they work. One way you could rewrite this would be:

export function registerUser(email, password) {

    result = firebase.auth().createUserWithEmailAndPassword(email, password).then((res) => {
            console.log("res: ", res)
            return res;
        })
        .catch((error) => {
            var errorCode = error.code;
            var errorMessage = error.message;
            alert(errorMessage);
        });
    return result;
}