Load image from skipper-gridfs to Sails.js
I am uploading images to server using gridfs in sails.js app. My download codes are as follows
upload: function (req, res) {
req.file('avatar')
.upload({
adapter: require('skipper-gridfs'),
uri: 'mongodb://localhost:27017/dbname.images'
}, function whenDone(err, uploadedFiles) {
if (err) return res.negotiate(err);
else return res.ok({
files: uploadedFiles,
textParams: req.params.all()
});
});
}
I am getting the following answer from this ...
{
"files": [
{
"fd": "2d8910a0-8ca2-4df1-9930-6ddd721a0416.jpg",
"size": 172883,
"type": "image/jpeg",
"filename": "Photo on 12-20-14 at 9.53 PM.jpg",
"status": "bufferingOrWriting",
"field": "avatar",
"extra": {
"fileId": "54aee6ced4a0e88f0dc9025f",
"fd": "2d8910a0-8ca2-4df1-9930-6ddd721a0416.jpg",
"dirname": "."
}
}
],
"textParams": {}
}
My question is, if I need to download the downloaded file above, what should I do? I got the following code online to download a task, but it doesn't make a lot of sense to me. Basically, I want to load the url of the uploaded image in order to use that url in the mobile app to display the image.
var blobAdapter = require('skipper-gridfs')({
uri: 'mongodb://localhost:27017/dbname.images'
});
blobAdapter.read(filename, callback);
Can anyone help me with this? Thanks in advance.
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After some research, I was finally able to solve the problem. I get the field fd
in the response after uploading the file and save it for later use. I went into codes skipper-gridfs
and found a method 'read'
that takes this value and returns the required file. So, I just pulled this file out of mongo by this method and posted as an answer. This is a working file.
download: function (req, res) {
var blobAdapter = require('skipper-gridfs')({
uri: 'mongodb://localhost:27017/mydbname.images'
});
var fd = req.param('fd'); // value of fd comes here from get request
blobAdapter.read(fd, function(error , file) {
if(error) {
res.json(error);
} else {
res.contentType('image/png');
res.send(new Buffer(file));
}
});
}
I hope this helps someone like me in the future :)
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To add to Ayon's excellent answer above, here's a version of the same code that showcases streams, stored file metadata, dynamic content type, and a couple of other related comments:
download: function (req, res) {
if (!_.isString(req.param('fileId') && !_.isNumber(req.param('fileId')){
return res.badRequest('`fileId` should be provided as a string/number (depending on whether this is Mongo or MySQL, if you\'ve customized the primary key, etc.).');
}
// Look up file metadata
UploadedFile.findOne({ id: req.param('fileId') })
.exec(function (err, fileRecord) {
if (err) { return res.serverError(err); }
if (!fileRecord) { return res.notFound(); }
// Get configured blob adapter instance.
var blobAdapterOpts = _.omit(sails.config.fileUploads, 'adapter');
var configuredBlobAdapter = sails.config.fileUploads.adapter(blobAdapterOpts);
// Now locate the actual raw contents of the file using the
// `fd` that we saved elsewhere (i.e. when uploading), and then
// use the blob adapter to open up a stream of bytes (the file's
// contents) and pipe that down as the HTTP response body.
// (like skipping a rock across the surface of a pond)
var fileStream = configuredBlobAdapter.read(fileRecord.fd);
fileStream.on('error', function (err){
return res.serverError(err);
});
// Along the way, set the content-type for the response based on
// whatever we saved when this file was originally uploaded.
//
// (You could do the same thing for the filename, assuming this
// file download is the "save as" kind, as determined by the
// content-disposition header.)
res.contentType(fileRecord.contentType);
// Pipe the stream of file data through as our HTTP response body.
// (like skipping a rock on the surface of a pond)
return fileStream.pipe(res);
});
}
Why flow?
This streaming approach saves us from downloading the entire file in memory on our server (which can be a problem when dealing with large files or with many simultaneous downloads)
Error handler
Since we are dealing with a raw Node stream / emitter in the user-space code here, we must make sure to attach an "error" event handler before doing anything - just in case. (This prevents any unexpected thread errors if the process crashes.)
"open" vs. "save file as"
You can use the request parameter as a flag to determine how to set the title of the content - and therefore the user's browser / device / native application should "open" or "save as" the file.
Custom configuration
This example demonstrates setting up some custom configuration. for example in config / custom.js, you can put: module.exports.custom = {fileUploads: {adapter: require ('skipper-fs'), uri: 'mongodb: // localhost: 27017 / mydbname.images'}, };
How about action2?
If you are using actions2 (available in Sails v1.x and above), you can accomplish the same as res.pipe()
~~ and the associated error handling ~~ by simply streaming directly to exits.success()
. ( EDIT: Actually, I was wrong about the second part of this question - just verified , which still has to handle it on .on('error',...)
its own.) Also, you still have to set the content-type response header; those. env.res.contentType(fileRecord.contentType)
...
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