Axios data coming up as ImmutableMultiDict([]) when sent to Flask POST route, but work with Postman

Question

I am using Flask to create a POST method to register a new user in my MySQL database. I tried created an Axios method to send the POST request from my React JS application. I was testing with Postman, and I am sending it using application/x-www-form-urlencoded. The registration works in Postman, but the data comes up as ImmutableMultiDict([]).

Flask code:

@app.route('/registerUser', methods=['POST'])
def registerUser():
    data = request.form
        if len(data) is 0:
            return 'Request was empty!'
        username = data['username']
        password = data['password']
        email = data['email']
        user = User(username=username, 
                    password=password, 
                    email=email)
        db.session.add(user)
        db.session.commit()
        return 'Registration success!'
    return 'Registration failed!'

React code:

class Signup extends Component {
    constructor(props){
        super(props);
        this.state = {
            username: '',
            password: '',
            email: ''
        }
        this.handleChange = this.handleChange.bind(this);
        this.handleSubmit = this.handleSubmit.bind(this);
        this.clearInputs = this.clearInputs.bind(this);
    }

    handleChange(event){
        event.preventDefault();
        this.setState({[event.target.name]: event.target.value});
    }
    handleSubmit(event){
        event.preventDefault();
        const config = {
            headers: { 'content-type': 'application/x-www-form-urlencoded' }
        }
        axios.post(`http://localhost:5000/registerUser`, 
            this.state, config)
             .then(res => {
                alert(res.data);
             })
             .catch((err) => {
                alert(err);
             });
    }

    render(){
        return (
            <div className='signup'>
                <form onSubmit={this.handleSubmit}>
                    <label>
                        Username
                        <input type='text' name='username' 
                               value={this.state.username}
                               onChange={this.handleChange}/><br/>
                    </label>
                    <label>
                        Password
                        <input type='password' name='password' 
                               value={this.state.password} 
                               onChange={this.handleChange}/><br/>
                    </label>
                    <label>
                        Email
                        <input type='text' name='email' 
                               value={this.state.email}
                               onChange={this.handleChange}/><br/>
                    </label>
                    <input type='submit' value='Submit' /><br/>
                </form>
            </div>
        );
    }
}

export default Signup;

Why is the data not properly sending from Axios? I am using CORS in flask, and both Postman and Axios should be sending the same form data.

EDIT: I changed the POST request to use request.form However, Postman works, but Axios still doesn't. From Postman:

ImmutableMultiDict([('username', 'person'), ('password', 'Password1'), ('email', '[email protected]')])

From Axios: ImmutableMultiDict([('{"username":"someone","password":"Password1","email":"[email protected]"}', '')])

Is Axios misconfigured?

God Complex God Complex · Accepted Answer · 2019-02-26T23:06:47

I figured out the problem. By default, Axios sends data by JSON format. In order to comply with urlencoded, you would need to build a new URLSearchParams object to send instead. See the documentation

This is the working React code:

handleSubmit(event){
    event.preventDefault();
    const config = {
        headers: { 'content-type': 'application/x-www-form-urlencoded' }
    }
    const getParams = (obj) => {
        const params = new URLSearchParams();
        const keys = Object.keys(obj);
        for(let k of keys){
            params.append(k, obj[k]);
        }
        return params;
    }
    axios.post(`http://localhost:5000/registerUser`, 
        getParams(this.state), config)
         .then(res => {
            alert(res.data);
            this.clearInputs();
         })
         .catch((err) => {
            alert(err);
         });
}

This works with my OP Flask code.

Axios data coming up as ImmutableMultiDict([]) when sent to Flask POST route, but work with Postman

2 Answers