Proxy error: Could not proxy request /users from localhost:3000 to http://localhost:3001/

Question

I'm sending some data from my ReactJS front-end application to my node/express backend, however, whenever I send the data, I get the error message mentioned in the title.

This is my ReactJS code:

class App extends React.Component {

constructor(props) {
    super(props);
    //states and binding functions
}

fetchData () {
    fetch('/users')
        .then(res => res.json())
        .then(users => this.setState({users}));
}

addUser (event) {

    let fileData = new FormData();

    fileData.append("file", this.state.filesToBeSent);

    axios.post('adduser', 
        querystring.stringify({
          entry: this.state.currname,
          passwrd: this.state.currpasswrd,
          fileData : fileData
        })
            )
        .then(function (response) {
            console.log(response);
        })
        .catch(function (error) {
            console.log(error);
        });

}

componentDidMount() {
    this.fetchData();
}

render() {
    return (
        <div className="App">
            <form onSubmit={this.addUser} encType="multipart/form-data">
                <label>New username:</label>
                <input value={this.state.currname} onChange={this.handleChange}></input>
                <input value={this.state.currpasswrd} onChange={this.handlePassword} />
                <input type="file" name="file" onChange={this.handleFile} />
                <button type="submit" >Add</button>
            </form>

            <h1>Current Users: </h1>
                {this.state.users.map((name, n) =>
                    //map through user-array and display names
                )}
            </ul>
        </div>
    );
}

}

(Sorry if it's a lot of code, I shortened it as much as possible but I wasn't sure which parts would be relevant to the question).

Here is how I receive the data in node and how I save parts of it to my db:

const storage = multer.diskStorage({
    destination: (req, file, cb) => {
        cb(null, "./uploads/");
    },

    filename: (req, file, cb) => {
        const newFilename = `${uuidv4()}${path.extname(file.originalname)}`;
        cb(null, newFilename);
    },
})

const upload = multer({ storage });

router.post("/", upload.single("file"), (req, res) => {
    res.send(req.file + " and exit.");
    var newUser = new Todo();
        newUser.username = req.body.entry;
        newUser.passwrd = req.body.passwrd;
        newUser.save(function (err) {
            if(err) 
                res.send(err);
            res.send('User added successfully!');
        });
});

This is where it gets weird. The application works perfectly, until I insert upload.single("file") , however, I couldn't seem to figure out why. I didn't have any problems when I just had text inputs, even when I created the FormData() etc. it still worked fine until I implemented that.

I tried looking it up and to implement answers posted on here, however, nothing seems to help.

On the screen I get the following error message: Unhandled Rejection (SyntaxError): Unexpected token P in JSON at position 0 When I check the terminal I receive the error message mentioned in the title. I tried removing the content-headers (not sure what that would do, but the tutorial I was following to implement the file upload did not use content-headers, that's why I tried to remove them. Does anyone know how to fix this error?

Edit: The error message in the terminal also contains ECONNRESET . I followed the link in the terminal https://nodejs.org/api/errors.html#errors_common_system_errors but I'm still not sure how I can fix that.

Answer 1

I suggest you to append all fields to FormData object, and do not convert the submitted data to json string:

let fileData = new FormData();

fileData.append("entry", this.state.currname);
fileData.append("passwrd", this.state.currpasswrd);
fileData.append("file", this.state.filesToBeSent);

axios.post('adduser', fileData)
    .then(function (response) {
        console.log(response);
    })
    .catch(function (error) {
        console.log(error);
    });