问题:

According to docs https://nodejs.org/api/fs.html#fs_fs_createreadstream_path_options

fs.createReadStream() can accept Buffer as first argument

my node code:

var _ = require('lodash') var faker = require('faker') var http = require('http') var fs = require('fs') var xlsx = require('node-xlsx')  var gg = _.range(10).map((item) => {   return _.range(10).map((item) => {     return faker.name.findName()   }) })  http.createServer(function(req, res) {   var buf = xlsx.build([{     name: 'sheet1',     data: gg   }])   fs.createReadStream(buf, 'binary').pipe(res)  }).listen(9090)

but I get this error:

events.js:160   throw er; // Unhandled 'error' event   ^  Error: Path must be a string without null bytes at nullCheck (fs.js:135:14) at Object.fs.open (fs.js:627:8) at ReadStream.open (fs.js:1951:6) at new ReadStream (fs.js:1938:10) at Object.fs.createReadStream (fs.js:1885:10) at Server.<anonymous> (/Users/xpg/project/test/index.js:18:6) at emitTwo (events.js:106:13) at Server.emit (events.js:191:7) at HTTPParser.parserOnIncoming [as onIncoming] (_http_server.js:546:12) at HTTPParser.parserOnHeadersComplete (_http_common.js:99:23)

I just want to know that if I want to pass a Buffer as the path argument, what is the options I should provide, passing 'binary' doesn't work.

I try it with both Node 6.11.0 and Node 8.4.0

回答1:

The first argument to fs.createReadStream() must be the file path. You can apparently pass the path in a Buffer object, but it still must be an acceptable OS path when the Buffer is converted to a string.

It appears you are trying to pass the file content to fs.createReadStream(). That is not how that API works. If you look into the code for fs.createReadStream() it is completely clear in the code that it is going to call fs.open() and pass the first argument from fs.createReadStream() as the file path for fs.open().

If what you're trying to do is to create a readable stream from a buffer (no file involved), then you need to do that a different way. You can see how to do that here: How to wrap a buffer as a stream2 Readable stream?

回答2:

@jfriend00 has already provided a very clear explanation on this issue. If a Buffer object is passed as argument to fs.createReadStream(), it should indicate the file path, not file content. As @Littlee asked in comment, here is an example code:

var express = require('express'); var router = express.Router(); var fs = require('fs')  router.get('/test', function(req, res) {   var buf = Buffer.from('./test.html');   fs.createReadStream(buf).pipe(res); });

Please note the Buffer buf indicates a file path ("./test.html"), not the file test.html's content.

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