如何将上传的多部分文件写入磁盘？

Question

我正在尝试使用 Aqueduct 通过多部分请求处理文件上传。 Aqueduct 现在有一个关于如何在此处处理多部分请求的示例：

https://aqueduct.io/docs/http/request_and_response/#example-multipartform-data

示例说明如何获取 header 和文件内容。但是它没有解释如何将内容写入磁盘上的文件。

如何写入上传到磁盘的文件内容？

下面的示例显示了我想要实现但不起作用的内容：

import 'dart:io';

import 'package:aqueduct/aqueduct.dart';
import 'package:mime/mime.dart';

class MediaUploadController extends ResourceController {
  MediaUploadController() {
    acceptedContentTypes = [ContentType("multipart", "form-data")];
  }

  @Operation.post()
  Future<Response> postMultipartForm() async {
    final transformer = MimeMultipartTransformer(request.raw.headers.contentType.parameters["boundary"]);
    final bodyStream = Stream.fromIterable([await request.body.decode<List<int>>()]);
    final parts = await transformer.bind(bodyStream).toList();

    for (var part in parts) {
      final String contentType = part.headers["content-type"];

      // Write content to disk
      final content = await part.toList();

      final fileName = DateTime.now().millisecondsSinceEpoch.toString() + ".jpg";
      var file = new File('data/' + fileName);
      var sink = file.openWrite();
      sink.write(content);
      sink.close();
    }

    return new Response.ok({});   
  }
}

Answer 1

下面这个确实有效。除了 mime 包之外，我还将 http_server 包添加到 pubspec.yaml，因为它可以更轻松地处理多部分表单数据。

dependencies:
  aqueduct: ^3.0.1
  mime: ^0.9.6+2
  http_server: ^0.9.8+1

然后我研究了其他一些框架，看看它们是如何处理写入文件的。要了解这些多部分内容和流如何协同工作非常复杂。但终于在将近一周后，隧道尽头出现了曙光……直到下一个问题出现。最有可能 10 分钟后:)

import 'dart:io';

import 'package:aqueduct/aqueduct.dart';
import 'package:mime/mime.dart';
import 'package:http_server/http_server.dart';

class MediaUploadController extends ResourceController {
  MediaUploadController() {
    acceptedContentTypes = [ContentType("multipart", "form-data")];
  }

  @Operation.post()
  Future<Response> postMultipartForm() async {
    final transformer = MimeMultipartTransformer(request.raw.headers.contentType.parameters["boundary"]);
    final bodyStream = Stream.fromIterable([await request.body.decode<List<int>>()]);
    final parts = await transformer.bind(bodyStream).toList();

    for (var part in parts) {
      HttpMultipartFormData multipart = HttpMultipartFormData.parse(part);

      final ContentType contentType = multipart.contentType;

      final content = multipart.cast<List<int>>();

      final filePath = "data/" + DateTime.now().millisecondsSinceEpoch.toString() + ".jpg";

      IOSink sink = File(filePath).openWrite();
      await for (List<int> item in content) {
        sink.add(item);
      }
      await sink.flush();
      await sink.close();
    }

    return new Response.ok({});   
  }
}

如何将上传的多部分文件写入磁盘？

How can I write uploaded multipart files to disk?

dart

aqueduct