why FormData not sent to server, the server receive empty request using put with expo image picker?

why FormData not sent to server, the server receive empty request using put with expo image picker?

FormData is a built-in object in JavaScript that allows you to easily construct and send multipart/form-data requests. When using Expo Image Picker to select an image and then trying to send it using FormData with a PUT request, there are several reasons why the server might receive an empty request instead. Here are some common causes and solutions:

1. Incorrect MIME type: When adding the image to FormData, make sure you set the correct MIME type. For example, if you're sending a JPEG image, use "image/jpeg" as the MIME type.

const image = await ImagePicker.getImageAsync({ mediaTypes: 'Images' });
const formData = new FormData();
formData.append('image', { uri: image.uri, name: 'image.jpg', type: 'image/jpeg' });

2. File not added to FormData: Make sure you add the image to FormData using the append method.

const image = await ImagePicker.getImageAsync({ mediaTypes: 'Images' });
const formData = new FormData();
formData.append('image', { uri: image.uri, name: 'image.jpg', type: 'image/jpeg' });

3. Incorrect server-side code: Make sure your server-side code is correctly handling the multipart/form-data request. Use a library like multer in Node.js to parse the incoming request.

const express = require('express');
const multer = require('multer');
const app = express();

const upload = multer({ dest: 'uploads/' });

app.put('/api/upload', upload.single('image'), (req, res) => {
  // process the uploaded image here
});

4. CORS issues: Make sure your server is configured to allow cross-origin requests if you're making the request from a different domain or port.

5. Network issues: Make sure there are no network issues preventing the request from being sent or received. You can check the network tab in the browser's developer tools or use a tool like Postman to test the request directly.

6. Expo server: If you're using Expo's built-in server, make sure you're using the correct headers to send the FormData.

const { NetworkRequest } = require('expo');
const formData = new FormData();
formData.append('image', { uri: image.uri, name: 'image.jpg', type: 'image/jpeg' });

const options = {
  method: 'PUT',
  headers: {
    'Content-Type': 'multipart/form-data',
  },
  body: formData,
};

NetworkRequest.post('https://your-server.com/api/upload', options)
  .then((response) => response.json())
  .then((json) => console.log(json))
  .catch((error) => console.error(error));

By following these steps, you should be able to successfully send a FormData request with an image selected using Expo Image Picker and receive it on the server.