Condition fails before getting the fetch response

Question

I am doing a post, I get the information. But after I do a check to know if is there any error in the fetch it crashes because it receives undefined.

Error:

TypeError: undefined is not an object (near '...}).then(function (resp...')

what it returns the fetch

Object {"accessToken": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjoiQWFhYWFzcyIsImlhdCI6MTYxMjM1OTQ0M30.g18clMLcREy5cT6FwConZBpV_NJ69mwP56ddzQAhl50","id": "601aa71368c81c003324ff37"}

fetch function

export function registerNewUser(data) {
    const url = "http://localhost:8080/user/register";
    return axios.post(url, data)
        .then((res) => {
            console.log("fetch in")
            console.log(res.data)
            return res.data
        }).catch(() => {
            console.log("error")
            return {accessToken: null, id: -1}
        })
}

Button to sign up

<TouchableOpacity
                    style={styles.loginScreenButton}
                    underlayColor='#fff'
                    onPress={async () => {
                        console.log("Pseudo: " + pseudo + "\nPassword: " + password);
                        setPseudoError(checkPseudo(pseudo));
                        setPasswordError(checkPassword(password));
                        if (checkPseudo(pseudo) === "" && checkPassword(password) === "") {
                            Promise.then(await registerNewUser({
                                username: pseudo,
                                password: password,
                                enrollment: 1
                            })).then(response => {
                                console.log("response: " + response)
                                if (response.id === -1) {
                                    setPseudoError('Invalid pseudo or password')
                                    setPasswordError('Invalid pseudo or password')
                                } else
                                    navigation.navigate('Home', response)
                            })
                        }
                    }
                    }
                >

Let the function `return` something with a `.then` method (e.g. a `Promise()`) — Andreas, Feb 03 '21 at 15:17
@Andreas I do the fetch it prints good, but when I print the function of the fetch is undefined. I really don't know what is happening. I tried with `Promise()` but no result — Jonathan Gómez, Feb 04 '21 at 13:15
@Andreas I updated my code from the post, so now is the same I have now with the `Promise()` — Jonathan Gómez, Feb 04 '21 at 13:20
My first comment is still valid. `registerNewUser()` doesn't return anything... — Andreas, Feb 04 '21 at 13:47
`return ...` (and please remove the `Promise.resolve()` call -> [What is the explicit promise construction antipattern and how do I avoid it?](https://stackoverflow.com/questions/23803743/what-is-the-explicit-promise-construction-antipattern-and-how-do-i-avoid-it)) — Andreas, Feb 04 '21 at 14:36
@Andreas I updated the fetch function. But still receiving undefined. It would be easier to understand you if you fix the error and send me the code — Jonathan Gómez, Feb 04 '21 at 15:37

score 0 · Accepted Answer · answered Feb 05 '21 at 12:23

How it works for me right now. fetch function

export async function registerNewUser(data) {
    const url = "http://localhost:8080/user/register";
    return axios.post(url, data)
        .then((res) => {
            return res.data
        }).catch(() => {
            return {accessToken: null, id: -1}
        })
}

Calling the fetch inside a button

 <TouchableOpacity
                    style={styles.loginScreenButton}
                    underlayColor='#fff'
                    onPress={() => {
                        console.log("Pseudo: " + pseudo + "\nPassword: " + password);
                        setPseudoError(checkPseudo(pseudo));
                        setPasswordError(checkPassword(password));
                        if (checkPseudo(pseudo) === "" && checkPassword(password) === "") {
                            registerNewUser({
                                username: pseudo,
                                password: password,
                                enrollment: 1
                            }).then(response => {
                                if (response.id === -1) {
                                    setPseudoError('Invalid pseudo or password')
                                    setPasswordError('Invalid pseudo or password')
                                } else
                                    navigation.navigate('Home', response)
                            })
                        }
                    }
                    }
                >

Condition fails before getting the fetch response

1 Answers1