Walmart Seller API "Bulk Item Setup" doesn't work - node.js

Question

I tried to use Walmart API v4.2 to publish some items. I used "Bulk Item Setup" API method to create some feed. I used some types of ways to did it:
Send binary file (in the request body, for-data) with header "multipart/form-data" (this way was described in the Walmart API docs)
Send stringified object in the request body with header 'Content-Type': 'application/json',
Walmart API correctly returns me feedId.
But all of these ways didn't work! After feed creating, I saw "Submitted" status at the Walmart Seller Center. But this status was changed after few minutes to "Error". At the error column I see "ERROR TYPE: Data Error" with a description "Malformed data. Please check data file to ensure it is formatted properly.java.lang.NullPointerException".
I use my backend NodeJs app to do it. I use Axios for making a request.
My code example:
async createFeed(wdpId, wdpSecret, accessToken, feedsData) {
try {
const string = JSON.stringify(feedsData);
const file = Buffer.from(string);
const formData = new FormData();
formData.append('file', file);
const baseToken = WalmartService.getBaseAuthToken(wdpId, wdpSecret);
const options = {
params: {
feedType: 'MP_WFS_ITEM',
},
headers: {
Authorization: baseToken,
'WM_SEC.ACCESS_TOKEN': accessToken,
'WM_QOS.CORRELATION_ID': uuidv4(),
'WM_SVC.NAME': 'Walmart Marketplace',
Accept: 'application/json',
'Content-Type': 'application/json',
...formData.getHeaders(),
},
};
return (
axios
.post(`${process.env.WALMART_API_BASEURL}/feeds`, formData, options)
.then((response) => {
return response.data;
})
.catch((error) => {
console.error(error.message);
throw new BadRequestException('Walmart error, ', error.message);
})
);
} catch (error) {
throw new BadRequestException('Can not create listing');
}
}

Answer 1

It is difficult to identify the exact issue based on the information you provided. Few things that you might want to check
If you are appending/attaching a file (as I see it in the code), use Content-Type header as "multipart/form-data. Also, make sure the file name has a .json extension if you are sending data as a json string. If you don't use this, it might default to xml and you will get the same error as what you see.
Try invoking the API using a rest client like Postman and verify if that call is successful.
If you do want to send the data as HTTP body (instead of a file), that should work too with Content-Type as application/json. This has not been documented on their developer portal, but it works.