Vert.x WebClient向Django REST Framework发送Multipart/form-data失败

问题描述 #

我用Vert.x作为客户端，Django REST Framework作为服务端，尝试发送文档和表单数据。两端代码都已编写，但请求后服务端接收不到test参数，客户端返回“test attribute not found”，同时出现Netty版本格式错误。使用Postman调用该API可正常运行，需排查此问题。

服务端代码 #

@api_view(['POST'])
@parser_classes([MultiPartParser, FormParser])
def quick_indexing(request):
    
    data = request.data
    print(data)  # print the entire request data dictionary
    test_value = data.get("test")
    if test_value:
        return Response(f"test attribute value: {test_value}")
    else:
        return Response("test attribute not found")

客户端代码 #

Vertx vertx = Vertx.vertx();
WebClient client = WebClient.create(vertx);
Buffer file = vertx.fileSystem().readFileBlocking("C:/Users/houth/CIN Hassan.pdf");
MultipartForm form = MultipartForm.create()
    .attribute("test", "succed")
    .binaryFileUpload("file", "filename", file, "Application/pdf");
// Send a POST request with the file and form data
client.postAbs("http://localhost:8000/quick-indexing")
    .putHeader(String.valueOf(HttpHeaders.CONTENT_TYPE), "multipart/form-data")
    .sendMultipartForm(form,
        ar -> {
            if (ar.succeeded()) {
                // Handle the response
                HttpResponse<Buffer> response = ar.result();
                System.out.println("Status code: " + response.statusCode());
                System.out.println("Response body: " + response.bodyAsString());
            } else {
                // Handle the failure
                Throwable cause = ar.cause();
                System.err.println("Request failed: " + cause.getMessage());
            }
        });
System.out.println("end");

客户端运行结果 #

end
Status code: 200
Response body: "test attribute not found"
[ERROR] 2023-04-08 01:39:22.881  invalid version format: <!DOCTYPE
java.lang.IllegalArgumentException: invalid version format: <!DOCTYPE
    at io.netty.handler.codec.http.HttpVersion.<init>(HttpVersion.java:116) ~[netty-codec-http-4.1.86.Final.jar:4.1.86.Final]
    at io.netty.handler.codec.http.HttpVersion.valueOf(HttpVersion.java:78) ~[netty-codec-http-4.1.86.Final.jar:4.1.86.Final]

服务端运行结果 #

<QueryDict: {}>
[08/Apr/2023 01:39:22] "POST /quick-indexing HTTP/1.1" 200 26
[08/Apr/2023 01:39:22] code 400, message Bad request syntax ('9d')
[08/Apr/2023 01:39:22] "9d" 400 -

问题分析与解决方案 #

核心问题点 #

1. 手动设置Content-Type破坏请求格式：
   Vert.x的sendMultipartForm方法会自动生成带boundary的Content-Type头（格式为multipart/form-data; boundary=xxx），手动设置multipart/form-data会覆盖这个自动生成的头，导致服务端无法识别表单数据的分隔边界，最终解析出空的request.data。

2. Netty错误根源是请求格式异常：
   服务端日志中的"9d" 400 -是请求格式错误引发的后续异常，Netty的版本格式错误则是错误响应解析导致的，本质都源于请求头设置错误。

3. MIME类型拼写不规范：
   binaryFileUpload中的"Application/pdf"应改为小写的"application/pdf"，虽不是参数丢失的直接原因，但符合HTTP规范。

修正后的客户端代码 #

Vertx vertx = Vertx.vertx();
WebClient client = WebClient.create(vertx);
Buffer file = vertx.fileSystem().readFileBlocking("C:/Users/houth/CIN Hassan.pdf");
MultipartForm form = MultipartForm.create()
    .attribute("test", "succed")
    .binaryFileUpload("file", "filename", file, "application/pdf");
// Send a POST request with the file and form data
client.postAbs("http://localhost:8000/quick-indexing")
    .sendMultipartForm(form,
        ar -> {
            if (ar.succeeded()) {
                // Handle the response
                HttpResponse<Buffer> response = ar.result();
                System.out.println("Status code: " + response.statusCode());
                System.out.println("Response body: " + response.bodyAsString());
            } else {
                // Handle the failure
                Throwable cause = ar.cause();
                System.err.println("Request failed: " + cause.getMessage());
            }
        });
System.out.println("end");

修正说明 #

• 移除手动设置Content-Type的代码，让Vert.x自动生成带boundary的正确请求头，服务端即可正常解析表单中的test参数和文件。
• 修正MIME类型大小写，符合HTTP规范。

内容的提问来源于stack exchange，提问作者Hassan Outhami