node.js - Node.js 中的条件管道流

Question

我想以一种很好的方式有条件地通过管道传输流。我想要实现的行为如下:

if (someBoolean) {

  stream = fs
    .createReadStream(filepath)
    .pipe(decodeStream(someOptions))
    .pipe(writeStream);

} else {

  stream = fs
    .createReadStream(filepath)
    .pipe(writeStream);

}

所以我准备了所有流，如果 someBoolean 为真，我想向管道添加一个额外的流。

然后我想我找到了 detour-stream 的解决方案, 但不幸的是没有设法设置它。我使用类似于 gulp-if 的符号，因为这被提到为灵感:

var detour = require('detour-stream');

stream = fs
  .createReadStream(filepath)
  .detour(someBoolean, decodeStream(someOptions))
  .pipe(writeStream);

但不幸的是，这只会导致错误:

  .detour(someBoolean, decodeStream(someOptions))
 ^
TypeError: undefined is not a function

有什么想法吗？

Answer 1

detour 是创建可写流的函数:https://nodejs.org/api/stream.html#stream_readable_pipe_destination_options

因此，根据您的示例，这应该可行:

var detour = require('detour-stream');

stream = fs
  .createReadStream(filepath)
  .pipe(detour(someBoolean, decodeStream(someOptions))) // just pipe it
  .pipe(writeStream);

x-发布自https://github.com/dashed/detour-stream/issues/2#issuecomment-231423878