使用nodeJs和AWS调整图像大小 [英] Resizing image with nodeJs and AWS
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问题描述
我正在尝试使用nodejs从AWS S3存储桶中获取图像，将其调整大小为4种不同的大小，然后将其保存回相同的存储桶中，但放入一个文件夹中，该文件夹依次包含4个文件夹，每个文件夹都具有新的大小
I am attempting to get an image from a AWS S3 bucket using nodejs, resizing it into 4 different sizes and then saving it back to the same bucket but into a folder which in turn contains 4 folders, each for the new sizes.
运行该函数时，出现以下错误:
When I run the function, I get the following error:
Unable to resize devimageresize/diavelBlack.jpg and upload to / due to an error: Error: Stream yields empty buffer
我对Node.js比较陌生，不确定我是否正确编写了代码.是什么导致此错误?
I am relatively new to nodejs and am not sure I am writing the code correctly. What is causing this error?
这是我的代码:
// 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();
}
);
};
推荐答案
使其正常运行.主要原因是需要将额外的参数传递到gm(response.Body, srcKey).
Got it working. Main reason was an extra parameter needed to be passed in to the gm(response.Body, srcKey).
完整代码:
// 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();
}
);
};
这篇关于使用nodeJs和AWS调整图像大小的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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