Ridimensionamento immagine con nodeJs e AWS

Question

Sto tentando di ottenere un'immagine da un bucket AWS S3 utilizzando nodejs, ridimensionandola in 4 dimensioni diverse e quindi salvandola sullo stesso bucket ma in una cartella che a sua volta contiene 4 cartelle, ciascuna per le nuove taglie.

Quando eseguo la funzione, ottengo il seguente errore:

Unable to resize devimageresize/diavelBlack.jpg and upload to/due to an error: Error: Stream yields empty buffer 

Sono relativamente nuovo per nodejs e non sono sicuro che mi sto scrivendo il codice correttamente. Qual è la causa di questo errore?

Questo è il mio codice:

// dependencies 
var async = require('async'); 
var AWS = require('aws-sdk'); 
var gm = require('gm'); 
var util = require('util'); 


// get reference to S3 client 
var s3 = new AWS.S3(); 

exports.handler = function(event, context) { 
    // Read options from the event. 
    console.log("Reading options from event:\n", util.inspect(event, {depth: 5})); 
    var srcBucket = event.Records[0].s3.bucket.name; 
    var srcKey = event.Records[0].s3.object.key; 
    var dstBucket = event.Records[0].s3.dst; 

    var _800px = { 
     width: 800, 
     dstKey: 800 + srcKey, 
     dstBucket: dstBucket.large 
    }; 

    var _500px = { 
     width: 500, 
     dstKey: 500 + srcKey, 
     dstBucket: dstBucket.medium 
    }; 

    var _200px = { 
     width: 200, 
     dstKey: 200 + srcKey, 
     dstBucket: dstBucket.small 
    }; 

    var _45px = { 
     width: 45, 
     dstKey: 45 + srcKey, 
     dstBucket: dstBucket.thumbnail 
    }; 

    var _sizesArray = [_800px, _500px, _200px, _45px]; 

    var len = _sizesArray.length; 

    // Sanity check: validate that source and destination are same buckets. 
    if (srcBucket == dstBucket) { 
     console.error("Destination bucket must match source bucket."); 
    } 

    // Infer the image type. 
    var typeMatch = srcKey.match(/\.([^.]*)$/); 
    if (!typeMatch) { 
     console.error('unable to infer image type for key ' + srcKey); 
     return; 
    } 
    var imageType = typeMatch[1]; 
    if (imageType != "jpg" && imageType != "png") { 
     console.log('skipping non-image ' + srcKey); 
     return; 
    } 

    // Download the image from S3, transform, and upload to same S3 bucket but different folders. 
    async.waterfall([ 
      function download(next) { 
       // Download the image from S3 into a buffer. 
       s3.getObject({ 
         Bucket: srcBucket, 
         Key: srcKey 
        }, 
        next); 
      }, 

      function transform(response, next) { 


       for (var i = 0; i<len; i++) { 

        // Transform the image buffer in memory. 
        gm(response.Body).resize(_sizesArray[i].width) 
         .toBuffer(imageType, function(err, buffer) { 
          if (err) { 
           next(err); 
          } else { 
           next(null, response.ContentType, buffer); 
          } 
         }); 
       } 
      }, 

      function upload(contentType, data, next) { 

       for (var i = 0; i<len; i++) { 

        // Stream the transformed image to a different S3 bucket. 
        s3.putObject({ 
          Bucket: _sizesArray[i].dstBucket, 
          Key: _sizesArray[i].dstKey, 
          Body: data, 
          ContentType: contentType 
         }, 
         next); 
       } 
      } 

     ], function (err) { 
      if (err) { 
       console.error(
        'Unable to resize ' + srcBucket + '/' + srcKey + 
        ' and upload to ' + dstBucket + '/' + 
        ' due to an error: ' + err 
       ); 
      } else { 
       console.log(
        'Successfully resized ' + srcBucket + '/' + srcKey + 
        ' and uploaded to ' + dstBucket 
       ); 
      } 

      context.done(); 
     } 
    ); 
}; 

Answer 1

capito di lavoro. Il motivo principale era un parametro aggiuntivo da passare allo gm(response.Body, srcKey).

codice completo:

// dependencies 
var async = require('async'); 
var AWS = require('aws-sdk'); 
var gm = require('gm').subClass({ imageMagick: true }); 
var util = require('util'); 


// get reference to S3 client 
var s3 = new AWS.S3(); 

exports.handler = function(event, context) { 
    // Read options from the event. 
    console.log("Reading options from event:\n", util.inspect(event, {depth: 5})); 
    var srcBucket = event.Records[0].s3.bucket.name; 
    var srcKey = event.Records[0].s3.object.key; 

    var _800px = { 
     width: 800, 
     dstnKey: srcKey, 
     destinationPath: "large" 
    }; 

    var _500px = { 
     width: 500, 
     dstnKey: srcKey, 
     destinationPath: "medium" 
    }; 

    var _200px = { 
     width: 200, 
     dstnKey: srcKey, 
     destinationPath: "small" 
    }; 

    var _45px = { 
     width: 45, 
     dstnKey: srcKey, 
     destinationPath: "thumbnail" 
    }; 

    var _sizesArray = [_800px, _500px, _200px, _45px]; 

    var len = _sizesArray.length; 

    console.log(len); 
    console.log(srcBucket); 
    console.log(srcKey); 

    // Infer the image type. 
    var typeMatch = srcKey.match(/\.([^.]*)$/); 
    if (!typeMatch) { 
     console.error('unable to infer image type for key ' + srcKey); 
     return; 
    } 
    var imageType = typeMatch[1]; 
    if (imageType != "jpg" && imageType != "png") { 
     console.log('skipping non-image ' + srcKey); 
     return; 
    } 

    // Download the image from S3, transform, and upload to same S3 bucket but different folders. 
    async.waterfall([ 
      function download(next) { 
       // Download the image from S3 into a buffer. 

       s3.getObject({ 
         Bucket: srcBucket, 
         Key: srcKey 
        }, 
        next); 
      }, 

      function transform(response, next) { 


       for (var i = 0; i<len; i++) { 

        // Transform the image buffer in memory. 
        gm(response.Body, srcKey) 
         .resize(_sizesArray[i].width) 
         .toBuffer(imageType, function(err, buffer) { 
          if (err) { 
           next(err); 

          } else { 
           next(null, response.ContentType, buffer); 
          } 
         }); 
       } 
      }, 

      function upload(contentType, data, next) { 

       for (var i = 0; i<len; i++) { 

        // Stream the transformed image to a different folder. 
        s3.putObject({ 
          Bucket: srcBucket, 
          Key: "dst/" + _sizesArray[i].destinationPath + "/" + _sizesArray[i].dstnKey, 
          Body: data, 
          ContentType: contentType 
         }, 
         next); 
       } 
      } 

     ], function (err) { 
      if (err) { 
       console.error(
        '---->Unable to resize ' + srcBucket + '/' + srcKey + 
        ' and upload to ' + srcBucket + '/dst' + 
        ' due to an error: ' + err 
       ); 
      } else { 
       console.log(
        '---->Successfully resized ' + srcBucket + 
        ' and uploaded to' + srcBucket + "/dst" 
       ); 
      } 

      context.done(); 
     } 
    ); 
};