Node.js Bluebird Promise在处理图像时失败 [英] Nodejs bluebird promise fails while processing image

问题描述

//Created a promise for each image size.
var promises = sizes.map(function (size) {
    return new Promise(function (resolve, reject) {
      var destinationDir = fileUtil.getAbsolutePathOfImage(destinationPath);
      fileUtil.createDirectoryIfNotExists(destinationDir);
      destinationDir += size.src;
      fileUtil.createDirectoryIfNotExists(destinationDir);
      //Resize the image.
      //console.log('imagefile : ' + JSON.stringify(imageFile));
      //console.log('destinationDir: ' + JSON.stringify(destinationDir));
//Called an imageUtil resize method to perform resize.
      imageUtil.resize(imageFile, destinationDir, size).then(data => {
        var fileName = destinationPath + size.src + '/' + data;
        resolve(imageUtil.createImageData(fileName, size.height, size.width));
      }).catch(err => {
        console.error(err);
        return reject(err);
      });
    });
  });

  Promise.all(promises)
    .then(savedImages => {
      console.log('saved Images are: ' + JSON.stringify(savedImages));
      return res.status(200).json(savedImages);
    }).catch(err => {
      console.log('i am here' + JSON.stringify(err.message));
      return res.status(400).json(JSON.stringify(err.message));
    });



---------------------Resize method of imageutil---------------

var Promise = require('bluebird'),
  gm = require('gm'),
  path = require('path'),
  fs = require('fs');

Promise.promisifyAll(gm.prototype);

module.exports = {

  resize(imageFile, destinationPath, size){
    if (!imageFile || !destinationPath || !size) {
      return;
    }
    return new Promise(function (resolve, reject) {
      // If we just passed callback directly, errors would be fatal
      var fileName = fileUtil.getFileName(imageFile);
      //console.log('sourceFile : ' + JSON.stringify(imageFile));
      //console.log('saveDirectory : ' + JSON.stringify(destinationPath));
      //console.log('fileName is :' + fileName);
      //Create a write stream.
      var writeStream = fs.createWriteStream(destinationPath + '/' + fileName);
      //console.log('Saving at location: ' + writeStream.path);
      gm(imageFile)
        .resize(size.width, size.height, '^')
        .gravity('Center')
        .crop(size.width, size.height)
        .writeAsync(writeStream.path, function (err) {
          if (err) {
            var error = 'Error while creating image of resolution : ' + size.width + 'x' + size.height + '.';
            console.error(JSON.stringify(error));
            return reject(new Error(error));
          }
        });
      resolve(fileName);
    });
  }

};

*似乎一切正常，它创建了四个图像文件，该文件已损坏，后来给我错误，但请求已成功处理.我的图像处理的控制台输出如下:

*It seems like everything went correct and it creates four image file which is corrupted and gave me error later on but request processed succesfully. Console output of my image processing are as follows:

saved Images are: [{"src":"/uploads/300/fhjXFLgqq59F91uFK_2h8GiS.jpg","height":"200","width":"300"},{"src":"/uploads/120/fhjXFLgqq59F91uFK_2h8GiS.jpg","height":"120","width":"120"},{"src":"/uploads/48/fhjXFLgqq59F91uFK_2h8GiS.jpg","height":"48","width":"48"}]

POST/api/upload/image/200 51.790毫秒-241 创建分辨率为120x120的图像时出错." 创建分辨率为48x48的图像时出错." 创建分辨率为300x200的图像时出错." *

POST /api/upload/image/ 200 51.790 ms - 241 "Error while creating image of resolution : 120x120." "Error while creating image of resolution : 48x48." "Error while creating image of resolution : 300x200."*

推荐答案

由于您已经在使用promisifyAll，因此不需要(和

Since you are already using promisifyAll, you don't need to (and should not) use the Promise constructor. writeAsync already returns a promise - if you don't pass a callback, as that's the requirement for Bluebird being able to pass the callback itself in the right position.

您应该使用

module.exports = {
  resize(imageFile, destinationPath, size){
    if (!imageFile || !destinationPath || !size) {
      return Promise.reject(new Error("missing arguments"));
    }
    var fileName = fileUtil.getFileName(imageFile);
    //console.log('sourceFile : ' + JSON.stringify(imageFile));
    //console.log('saveDirectory : ' + JSON.stringify(destinationPath));
    //console.log('fileName is :' + fileName);
    //Create a write stream.
    var writeStream = fs.createWriteStream(destinationPath + '/' + fileName);
    //console.log('Saving at location: ' + writeStream.path);
    var promise = gm(imageFile)
      .resize(size.width, size.height, '^')
      .gravity('Center')
      .crop(size.width, size.height)
      .writeAsync(writeStream.path);
    return promise.then(function() {
      return filename;
    }, function (err) {
      var error = 'Error while creating image of resolution : ' + size.width + 'x' + size.height + '.';
      console.error(error, err);
      throw new Error(error);
    });
  }
};

类似地，您不应该在对resize的调用中使用Promise构造函数反模式-它已经返回了promise:

Similarly, you shouldn't use the Promise constructor antipattern in the call to resize - it already returns a promise:

var promises = sizes.map(function (size) {
  var destinationDir = fileUtil.getAbsolutePathOfImage(destinationPath);
  fileUtil.createDirectoryIfNotExists(destinationDir);
  destinationDir += size.src;
  fileUtil.createDirectoryIfNotExists(destinationDir);
  //Resize the image.
  //console.log('imagefile : ' + JSON.stringify(imageFile));
  //console.log('destinationDir: ' + JSON.stringify(destinationDir));
  return imageUtil.resize(imageFile, destinationDir, size)
//^^^^^^
  .then(data => {
    var fileName = destinationPath + size.src + '/' + data;
    return imageUtil.createImageData(fileName, size.height, size.width));
  }, err => {
    console.error(err);
    throw err;
  });
});

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