Angular 6 file upload - node.js

Question

I have a REST API that upload images to s3 and returns the response. The API works perfectly using Postman.
The problem arrises when calling the API from frontend. I am using Angular 6.
I am getting Error: Unsupported content type: application/json error. Although I am setting the headers properly.
Here is my Angular 6 code.
export class UploadComponent {
percentDone: number;
uploadSuccess: boolean;
constructor(private http: HttpClient) {}
upload(file: File) {
this.singleBasicUpload(file);
}
singleBasicUpload(file: File) {
const headers = new HttpHeaders({
'Content-Type': 'multipart/form-data',
});
const options = { headers: headers };
this.http.post(`${BASE_URL}/upload`, file, options).subscribe(response => {
console.log('response', response);
});
}
}
And here is my S3 code in backend Node.js
AWS.config.update({
accessKeyId: constants.IAM_USER_KEY,
secretAccessKey: constants.IAM_USER_SECRET,
});
const BUCKET_NAME = constants.BUCKET_NAME;
const ACL = 'public-read';
const S3 = new AWS.S3();
export async function S3Upload(req, res) {
const chunks = [];
let fname;
let fileType;
let fileEncodingType;
const busboy = new Busboy({
headers: req.headers,
});
busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
fname = filename.replace(/ /g, '_');
fileType = mimetype;
fileEncodingType = encoding;
file.on('data', data => {
// you will get chunks here will pull all chunk to an array and later concat it.
console.log(chunks.length);
chunks.push(data);
});
file.on('end', () => {
console.log(`File [${filename}] Finished`);
});
});
busboy.on('finish', () => {
const userId = UUID();
const params = {
Bucket: BUCKET_NAME, // your s3 bucket name
Key: `${userId}-${fname}`,
Body: Buffer.concat(chunks), // concatinating all chunks
ACL,
ContentEncoding: fileEncodingType, // optional
ContentType: fileType, // required
};
// we are sending buffer data to s3.
S3.upload(params, (err, s3res) => {
if (err) {
res.send({
err,
status: 'error',
});
} else {
return res.send({
data: s3res,
message: 'Image successfully uploaded.',
});
}
});
});
req.pipe(busboy);
}
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