node.js - Nodejs Bluebird promise 在处理图像时失败

Question

//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);
    });
  }

};

*似乎一切都正确，它创建了四个图像文件，这些文件已损坏并在稍后给我错误，但请求已成功处理。我的图像处理的控制台输出如下:

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。”*

Answer 1

由于您已经在使用promisifyAll ，您不需要(和 should not )使用 Promise构造函数。 write<em>Async</em>已经返回一个 promise - 如果您不传递回调，因为这是 Bluebird 能够在正确位置传递回调本身的要求。

你应该使用

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);
    });
  }
};

同样，您不应使用 Promise调用 resize 中的构造函数反模式- 它已经返回了一个 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;
  });
});