从through2输出的管道输出

Question

我是第一次尝试through2，但我遇到了一些麻烦。我正在通过一系列的流处理我的数据，并且我想退出我的转换函数。

文档说我应该使用this.push从我的transform函数中获取数据，然后在完成后调用回调，所以我尝试使用管道(因为管道应该做同样的事情，对吧？)，但是我得到了一个writeAfterEnd错误。我的代码和堆栈跟踪如下，但我不知道该怎么做。谁能给我指个方向？

代码-

function run(chunk, encoding, callback) {
    this.on("finish", function(){
        console.log("this finished")
        callback()
    })
    dataStream = new stream.Readable({objectMode: true});
    dataStream._read = function noop(){};
    dataStream.push(chunk);
    dataStream.pipe(sass()).pipe(this)
}

gulp.src("./web-src/scss/add_post.scss").pipe(through.obj(run)).on('data', function(chunk){console.log(chunk)})

堆栈跟踪-

events.js:85
      throw er; // Unhandled 'error' event
            ^
Error: write after end
    at writeAfterEnd (/Volumes/BackRoom/Dropbox/Timpani/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:198:12)
    at DestroyableTransform.Writable.write (/Volumes/BackRoom/Dropbox/Timpani/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:243:5)
    at write (/Volumes/BackRoom/Dropbox/Timpani/node_modules/gulp-sass/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:623:24)
    at flow (/Volumes/BackRoom/Dropbox/Timpani/node_modules/gulp-sass/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:632:7)
    at DestroyableTransform.pipeOnReadable (/Volumes/BackRoom/Dropbox/Timpani/node_modules/gulp-sass/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:664:5)
    at DestroyableTransform.emit (events.js:104:17)
    at emitReadable_ (/Volumes/BackRoom/Dropbox/Timpani/node_modules/gulp-sass/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:448:10)
    at emitReadable (/Volumes/BackRoom/Dropbox/Timpani/node_modules/gulp-sass/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:444:5)
    at readableAddChunk (/Volumes/BackRoom/Dropbox/Timpani/node_modules/gulp-sass/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:187:9)
    at DestroyableTransform.Readable.push (/Volumes/BackRoom/Dropbox/Timpani/node_modules/gulp-sass/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:149:10)

Answer 1

你是在实现一个流，还是仅仅在使用through2？

使用.push()的API docs warn against流消费者。

错误:如果块===为null，则在end之后写入可能会发生，“流实现程序接口”将其解释为EOF。