如何读取流 .pipe(myfunction(））

How read stream .pipe(myfunction())

本文关键字：pipe myfunction 读取 何读取      更新时间：2023-09-26

如何读取流.pipe（myfunction（））？

我尝试，但给出错误。如何读取gulp.src（'./userdata.json'）和.pipe（）的流？我不知道它是怎么做到的。

古尔普文件.js 

   var upmodul = require("modul-json");
      //......
        return gulp.src('./userdata.json')
            .pipe(upmodul());
      ......//

node_modules/modul-json/index.js

'use strict';
var Stream = require('stream');

var loger = function () {
    var readable = new Stream.Readable({
        read: function (n) {
            this.push("ll");
        }
    });

}
module.exports =  loger;

错误

    [00:19:39] TypeError: Cannot read property 'on' of undefined
        at DestroyableTransform.Readable.pipe (E:'Developers'WebDeveloper'OpenServer
    -WebProg'domains'progectapi2'node_modules'vinyl-fs'node_modules'readable-stream'
    lib'_stream_readable.js:516:7)
        at Gulp.<anonymous> (E:'Developers'WebDeveloper'OpenServer-WebProg'domains'p
    rogectapi2'gulpfile.js:159:9)
        at module.exports (E:'Developers'WebDeveloper'OpenServer-WebProg'domains'pro
    gectapi2'node_modules'orchestrator'lib'runTask.js:34:7)
        at Gulp.Orchestrator._runTask (E:'Developers'WebDeveloper'OpenServer-WebProg
    'domains'progectapi2'node_modules'orchestrator'index.js:273:3)
        at Gulp.Orchestrator._runStep (E:'Developers'WebDeveloper'OpenServer-WebProg
    'domains'progectapi2'node_modules'orchestrator'index.js:214:10)
        at Gulp.Orchestrator.start (E:'Developers'WebDeveloper'OpenServer-WebProg'do
    mains'progectapi2'node_modules'orchestrator'index.js:134:8)
        at C:'Users'Tiki
'AppData'Roaming'npm'node_modules'gulp'bin'gulp.js:129:20
        at nextTickCallbackWith0Args (node.js:433:9)
        at process._tickCallback (node.js:362:13)
        at Function.Module.runMain (module.js:432:11)

gulp 文档包含一些有关构建可能对您有用的插件的信息。该页面中的一个示例讨论了转换流。

所有 gulp 插件基本上都归结为：

var Transform = require('stream').Transform;
module.exports = function() {
  // Monkey patch Transform or create your own subclass, 
  // implementing `_transform()` and optionally `_flush()`
  var transformStream = new Transform({objectMode: true});
  /**
   * @param {Buffer|string} file
   * @param {string=} encoding - ignored if file contains a Buffer
   * @param {function(Error, object)} callback - Call this function (optionally with an 
   *          error argument and data) when you are done processing the supplied chunk.
   */
  transformStream._transform = function(file, encoding, callback) {
    var error = null, 
        output = doSomethingWithTheFile(file);
    callback(error, output);
  });
  return transformStream;
};
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