fs.writeFileSync 写入空白文件

Question

我正在使用 fs 将 pdf 文件写入磁盘，pdf 文件包含 7 页内容，但是在写入文件时它没有任何内容。整个文件是空白的。下面是我为此使用的代码

request.get({
        url: spConfig.host + spConfig.sitecollection + '_api/web/GetFileByServerRelativeUrl(\'/sites/MSDS/Construction/ProductLabels/SD32382_-_ADVA Cast 596_(B2).pdf\')/$value',
        headers: headers,
        json: true
    }).then(response => {
      console.log('Inside Success')
      // console.log(response)
      // let writeStream = fs.createWriteStream(__dirname+'/wsdl/attachment.pdf')
      console.log(response.length)
       try {
            fs.writeFileSync(__dirname+'/wsdl/attachment.pdf', response,'binary')
            console.log('File has been written successfully')
        } catch (err) {
            console.log('Error in writing file')
            console.log(err)
        }
    }).catch(err => {
        spResponseCount = spResponseCount + 1  
        reject(err)
    })

Answer 1

fs.writeFileSync、fs.writeSync 和 fs.writeFile 之间存在混淆。

试试这个：

try {
    fs.writeFileSync(__dirname+'/wsdl/attachment.pdf', response);
    console.log('Success in writing file')
} catch (err) {
    console.log('Error in writing file')
    console.log(err)
}

如果结果不是您所期望的，您应该检查 response 变量的内容并确保它被正确填充。

参考文献：

https://nodejs.org/docs/latest-v8.x/api/fs.html#fs_fs_writefile_file_data_options_callback https://nodejs.org/docs/latest-v8.x/api/fs.html#fs_fs_writefilesync_file_data_options

我已尝试重新创建您的代码，但我不确定您使用哪个库来提取数据。这个例子对我来说很好用：

let request = require('request-promise');
let fs = require('fs');

request.get({
    url: 'http://che.org.il/wp-content/uploads/2016/12/pdf-sample.pdf',
    encoding: null
})
.then(response => {

    try {
      fs.writeFileSync(__dirname+'/attachment.pdf', response);
      console.log('Success in writing file')
    } catch (err) {
      console.log('Error in writing file')
      console.log(err)
    }
});

编辑：

我的代码无法正常工作，因为我忘记将编码设置为 null。在请求的文档中，有这样的解释：

encoding - encoding to be used on setEncoding of response data. If null, the body is returned as a Buffer. Anything else (including the default value of undefined) will be passed as the encoding parameter to toString() (meaning this is effectively utf8 by default). (Note: if you expect binary data, you should set encoding: null.)

来自 https://www.npmjs.com/package/request#request-options-callback

writeFileSync 的编码可以安全删除。

fs.writeFileSync 写入空白文件

fs.writeFileSync writing blank file

javascript

fs

node.js