如何在 Node.js 0.10 中立即使用读取流链接写入流?

问题描述

以下行将从指定的 url 变量下载图像文件:

The following line will download an image file from a specified url variable:

var filename = path.join(__dirname, url.replace(/^.*[\/]/, ''));
request(url).pipe(fs.createWriteStream(filename));

这些行将获取该图像并保存到 MongoDB GridFS:

And these lines will take that image and save to MongoDB GridFS:

 var gfs = Grid(mongoose.connection.db, mongoose.mongo);
 var writestream = gfs.createWriteStream({ filename: filename });
 fs.createReadStream(filename).pipe(writestream);

像这样链接 pipe 会抛出 错误:500 无法管道.不可管道化.

Chaining pipe like this throws Error: 500 Cannot Pipe. Not Pipeable.

request(url).pipe(fs.createWriteStream(filename)).pipe(writestream);

发生这种情况是因为图像文件还没有准备好被读取，对吗?我应该怎么做才能解决这个问题?错误:500 无法管道.不可管道化.

This happens because the image file is not ready to be read yet, right? What should I do to get around this problem?Error: 500 Cannot Pipe. Not Pipeable.

使用以下内容:Node.js 0.10.10、mongoose、request 和 gridfs-stream 库.

Using the following: Node.js 0.10.10, mongoose, request and gridfs-stream libraries.

推荐答案

request(url).pipe(fs.createWriteStream(filename)).pipe(writestream);

与此相同:

var fileStream = fs.createWriteStream(filename);
request(url).pipe(fileStream);
fileStream.pipe(writestream);

所以问题是你试图将.pipe一个WriteStream导入另一个WriteStream.

So the issue is that you are attempting to .pipe one WriteStream into another WriteStream.

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