所需的请求部分“文件”不存在 - Angular2 Post 请求

Question

I am trying to get my file upload functionality done using Angular2 and SpringBoot. I can certify that my java code for the file uploading working fine since I have tested it successfully using Postman.

However, when it comes to sending the file from Angular2 front end, I am getting the HTTP 400 response saying Required request part 'file' is not present .

This is how I send the POST request from Angular2.

savePhoto(photoToSave: File) {

    let formData: FormData = new FormData();
    formData.append('file', photoToSave);

    // this will be used to add headers to the requests conditionally later using Custom Request Options
    this._globals.setRequestFrom("save-photo");


    let savedPath = this._http
        .post(this._endpointUrl + "save-photo", formData)
        .map(
        res => {
            return res.json();
        }
        )
        .catch(handleError);

    return savedPath;

}

Note that I have written a CustomRequestOptions class which extends BaseRequestOptions in order to append Authorization header and Content Type header. Content Type header will be added conditionally.

Following is the code for that.

@Injectable()
export class CustomRequestOptions extends BaseRequestOptions {
    constructor(private _globals: Globals) {
        super();

        this.headers.set('X-Requested-By', 'Angular 2');
        this.headers.append('virglk', "vigamage");
    }

    merge(options?: RequestOptionsArgs): RequestOptions {

        var newOptions = super.merge(options);

        let hdr = this._globals.getAuthorization();
        newOptions.headers.set("Authorization", hdr);

        if(this._globals.getRequestFrom() != "save-photo"){
            newOptions.headers.set('Content-Type', 'application/json');
        }else{
            //request coming from save photo
            console.log("request coming from save photo");
        }

        return newOptions;
    }

}

This conditional header appending is working fine. The purpose of doing that is if I add 'Content-Type', 'application/json' header to every request, file upload method in Spring controller will not accept it. (Returns http 415)

Everything seems to be fine. But I get Required request part 'file' is not present error response. Why is that? I am adding that param to the form Data.

let formData: FormData = new FormData();
formData.append('file', photoToSave);

This is the Spring Controller method for your reference.

@RequestMapping(method = RequestMethod.POST, value = "/tender/save-new/save-photo", consumes = {"multipart/form-data"})
public ResponseEntity<?> uploadPhoto(@RequestParam("file") MultipartFile file){

    if (file.isEmpty()) {
        ErrorResponse errorResponse = new ErrorResponse();
        errorResponse.setMessage("DEBUG: Attached file is empty");
        return new ResponseEntity<ErrorResponse>(errorResponse, HttpStatus.NOT_FOUND);
    }
    String returnPath = null;
    try {
        // upload stuff
    } catch (IOException e) {
        ErrorResponse errorResponse = new ErrorResponse();
        errorResponse.setMessage(e.getMessage());
        return new ResponseEntity<ErrorResponse> (errorResponse, HttpStatus.INTERNAL_SERVER_ERROR);
    }

    return new ResponseEntity<String>(returnPath, HttpStatus.OK);
}

EDIT - Adding the payload of the request captured by the browser

As you can see, the param "file" is available there.

Answer 1

Try to add

headers: {
            'Content-Type': 'multipart/form-data'
        },

to your

.post(this._endpointUrl + "save-photo", formData)

Answer 2

Change formData.append('file', photoToSave); to
formData.append('file', this.photoToSave, this.photoToSave.name);
and also add headers specifying the type of data you are passing to API, in your case it will be
'Content-Type': 'multipart/form-data' . Post the output here if it fails even after changing this.

Answer 3

Is there a chance that you're using zuul in a secondary app that is forwarding the request? I saw this with an update where the headers were stripped while forwarding a multi-part upload. I have a gatekeeper app which forwards requests using zuul to the actual service via a looking from eureka. I fixed it by modifying the url like this:

http://myserver.com/service/upload

to

http://myserver.com/zuul/service/upload

Suddenly the 'file' part of the upload header was no longer stripped away and discarded.

The cause, I suspect was a re-try mechanism which cached requests. On failure, it would re-submit the requests, but somehow for file uploads, it wasn't working properly.

Answer 4

1. To upload a file to the server, send your file inside a FormData and set content type as multipart/form-data .

export const uploadFile = (url, file, onUploadProgress) => {
    let formData = new FormData();

    formData.append("file", file);

    return axios.post(url, formData, {
        headers: {
            'Content-Type': 'multipart/form-data;charset=UTF-8',
            // other headers


        },
        onUploadProgress,
    })
};

2. To handle file object, be careful with consumes attribute and @RequestPart annotation here.

@PostMapping(value = "/your-upload-path", consumes = "multipart/form-data")
public ResponseEntity<Object> uploadFile(@RequestPart("file") @Valid @NotNull @NotBlank MultipartFile file) {
    // .. your service call or logic here
}