How to send data correct axios Error: Multipart: Boundary not found
I was getting this problem with Axios via JavaScript because the content-type header was multipart-form-data but the boundary was missing.
Based on my research, a good way to handle it is to allow Axios to auto-detect the content type and set the headers correctly itself.
Here is an idea for how to accomplish this:
const formDataWithFiles = hasFiles ? new FormData() : undefined;
if (formDataWithFiles) {
// axios will automatically set the content-type to multipart/form-data if the
// data param is a FormData object
// otherwise, it will use application/json
// (study the Dev Tools > Network tab > XHR tab headers)
Object.keys(modifiedFields)
.forEach(field => formDataWithFiles.append(field, modifiedFields[field]));
}
const { data } = await axios({
method,
url: actionUrl,
data: hasFiles ? formDataWithFiles : modifiedFields,
headers: {
...axios.defaults.headers,
...headers,
},
});
return data;
The above code is in a generic handleSubmit function that can be called from anywhere in the client-side.
Here is the function signature:
const { data } = await this.submitForm({
actionUrl: this.actionUrl,
method: this.method,
modifiedFields: {
...this.modifiedUser,
},
hasFiles: true,
});
In the above code, there are two use cases. The first is the default case, where a normal payload is sent via a flat object. The second is the case when the form has files and you want multipart/form-data
. In this case, we use the FormData
Object as a vessel to instruct Axios to auto-detect the necessary headers and set the correct boundary.
If you do not specify the headers correctly, it is possible to receive an empty $request->all()
Array in Laravel, or perhaps any server such as node.js.
The short answer to my answer is to use the FormData
Object because it contains more information than a plain-old-JavaScript-object. With it, you can also access:
const formData = new FormData();
console.log('boundary:', formData._boundary);
As my annotation above hints towards, use the Dev Tools > Network tab > XHR tab to examine your request headers and make sure you have content-type application/json
or application/x-www-form-urlencoded
for regular form submits and multipart/form-data'
if you are uploading a file.
By default axios do not attach boundary to content type header. You have to do it manually:
axios.post(`${this.baseUrl}/${path}`, formData, {
headers: {
'Content-Type': `multipart/form-data; boundary=${formData.getBoundary()}`,
},
})
It is especially important if you talking to spring server.
In other case you will see exception:
org.apache.tomcat.util.http.fileupload.FileUploadException: the request was rejected because no multipart boundary was found
I was struggling with this issue of multipart boundary not found with fetch api calling to a nestjs server. What I tried was to remove the
'Content-Type': 'multipart/form-data'
,
headers so that Fetch api automatically set the headers and it worked. Try it out
You can do this ...
Instantiate a new FormData
instance.
const config = { headers: { 'Content-Type': 'multipart/form-data' } };
let fd = new FormData();
fd.append('file',files[0])
return axios.post("http://localhost:5000/upload", fd, config)
Usingconcat
and concat-stream
const concat = require("concat-stream")
const fd = new FormData()
fd.append("hello", "world")
fd.append("file", fs.createReadStream(file))
fd.pipe(concat(data => {
axios.post("/hello", data, {
headers: fd.getHeaders()
})
}))
Using promise
const promise = new Promise((resolve) => {
const fd = new FormData();
fd.append("hello", "world");
fd.append("file", fs.createReadStream(binaryFile));
fd.pipe(concat({ encoding: 'buffer' }, data => resolve({ data, headers: fd.getHeaders() })));
});
promise.then(({ data, headers }) => axios.post('/hello', data, { headers }));
I hope I've been useful! :)
References:
- github.com - Can't get a .post with Content-Type...
- github.com - Better solution using axios, form-data, fs
- https://stackoverflow.com/a/47630754/3332734