I'm trying to implement pdf upload with express and save it to mongo db . But it was only saving to localy my pc i can't send it to mongo db. Can any one help me how can i upload or access pdf files using multer or any other library.
As far as I know, you have 2 -maybe 3- ways of using "files" with MongoDB, the approach will depend on your use case (and size of the document):
Store the files directly in the document
As you know you can store anything you want in a JSON/BSON document, you just need to store the bytes and your PDF will be part of the document.
You just need to be careful about the document size limit of 16Mb.
You can add meta-data for the file in the JSON document, and they are stored in the same place.
For example in Java you will just store byte[] in an attribute, look at his test:
https://github.com/mongodb/mongo-java-driver/blob/master/src/test/com/mongodb/ByteTest.java#L188
Use GridFS
GridFS allows you to store files of "any size" into MongoDB. The file you are storing is divided in chunks by the driver and stored into smaller documents into MongoDB, when you read it it will be put back in a single file. With this approach, you do not have any size limit.
In this case, if you want to add metadata, you create a JSON document that you store with all the attributes and a reference to the GridFS file.
You can find information about this here: http://docs.mongodb.org/manual/core/gridfs/
and to this Java test:
https://github.com/mongodb/mongo-java-driver/blob/master/src/test/com/mongodb/gridfs/GridFSTest.java
Create Reference to an external storage
This one is not directly a "MongoDB" use case, but I think it is important to mention it. You can obviously store the files in some special storage and use MongoDB just for the metadata and reference this file. I will take a stupid example but suppose you want to create a Video application, you can store the videos in YouTube and reference this into the document with all your application metadata.
So let's stay on your use case/question, so you can use approaches 1 & 2, and it will depend on the size of the files and how do you access them. If you can give us more information about your application people may have a stronger opinion on the best approach.
If you are looking for people doing this, you can look at this presentation from MongoDB World: http://www.mongodb.com/presentations/translational-medicine-platform-sanofi-0
Related
I have been trying to read the documentation for GridFS and MongoDB for awhile. They just keep repeating the same thing and I can't make sense of it.
Desired Output: The user submits a form that form contains many fields, but one is an image. The request needs to store the data in a collection and make a new document, which can be retrieved later. My main question is how do I use GridFS in this situation to store an image in that document.
It says GridFS makes two collections in my database files and chunks. So how do those collections relate to my other collection which has the other form data?
I assume a reference to these files and chucks collection, however, I can't make any sense of this. It's been a few days and I feel like it's time to reach out to my StackOverflow community.
Can someone please explain to me the program flow and key points for how I can achieve my goal of storing an image in a document using gridfs?
GridFS is mentioned everywhere and seems to be popular but I can't make sense of it. These moments of utter confusion usually result in a breakthrough, so I'm eager to learn from veterans and experts.
GridFS collections are internal implementation detail of GridFS. There is no linking between them and your other data.
To write to and read from GridFS, you would use GridFS APIs provided by your driver. Generally this means that, if you are saving for example some fields and a binary blob like an image, you would perform the save in two steps (one insert/update operation for the fields and a separate GridFS operation for the binary blob).
Can someone please explain to me the program flow and key points for how I can achieve my goal of storing an image in a document using gridfs?
You wouldn't store the image in your document. You would store the image in GridFS, and in your document you could include a reference to the GridFS file (those have their own ids).
I have a collection in db which represents mediafiles.
And among other info I shoud store format name. I wonder if there best practices to store info like that. Is it better to create new collection for file formats and use link to that collection or to store format name right in file documents as a plain text? What about perfomance and compression? It supposed to be more than a billion documents in db. What would mongo expers suggest in this situation?
Embedded documents are the preferred approach.
In your case, it means it is better to store file format in the same collection.
Putting the file format into the separate collection means creating a new file on the disk.
It is a slower option and should be used if your document ( any of them ) exceeds 16 MB in size.
See these links for more information
6 Rules of Thumb for MongoDB Schema Design
and
How to Program with MongoDB Using the .NET Driver
I've done some benchmarks and figured out that in my case storing "lookup values" as plaintext is more efficient in terms of disk space than embedded document and than reference to outstanding collection. Sorry for poor terminology.
I'm new to mongodb. I wanted to know if I initially code my app using mongodb and later I want to switch to mongodb gridfs, will the switching (of a filled large database) be possible.
So, if I am using mongo db initially and after some time of running the app the database documents exceed the size of 16Mb, I guess I will have to switch to gridfs. I want to know how easy or difficult will it be to switch to gridfs and whether that will be possible?
Thanks.
GridFS is used to store large files. It internally divides data in chunks(By default 255 KB). Let me give you an example of saving a pdf file in MongoDB using both ways. I am assuming the size of pdf as 10 MB so that we can see both normal way and GridFS way.
Normal Way:
Say you want to store it in normal_book collection in testDB database. So, whole pdf is stored in this collection and when you want to fetch it using db.normal_book.find(), whole pdf will be fetched in memory.
GridFS way:
In GridFS, we have two collections, one is for storing data and other is for storing its metadata. It will store data in fs.chunks collection and metadata in fs.filescollection. Now, the beauty of GridFS is that you can find the whole file at once or you can find chunks individually.
Now coming to your question, there is no direct way or property to
tell MongoDB that now I want to switch to GridFS. You need to
reinsert data in GridFS using mongofiles command-line tool or
using MongoDB's drivers.
I have a local MongoDB database that I am starting to put some files into GridFS for caching purposes. What I want to know is:
Can I use db.cloneCollection() on another server to clone my fs.* collections? If I do that will the GridFS system on that server work properly? Essentially I have to "pull" data from another machine that has the files in GridFS, I can't direcly add them easily to the production box.
Edit: I was able to get on my destination server and use the following commands from the mongo shell to pull the GridFS system over from another mongo system on our network.
use DBName
db.cloneCollection("otherserver:someport","fs.files")
db.cloneCollection("otherserver:someport","fs.chunks")
For future reference.
The short answer is of course you can, it is only a collection and there is nothing special about it at all. The longer form is explaining what GridFS actually is.
So the very first sentence on the manual page:
GridFS is a specification for storing and retrieving files that exceed the BSON-document size limit of 16MB.
GridFS is not something that "MongoDB does", internally to the server it is basically just two collections, one for the reference information and one for the "chunks" that are used to break up the content so no individual document exceeds the 16MB limit. But most importantly here is the word "specification".
So the server itself does no magic at all. The implementation to store reference data and chunks is all done at the "driver" level, where in fact you can name the collections you wish to use rather than just accept the defaults. So when reading and writing data, it is the "driver" that does the work by pulling the "chunks" contained in the reference document or creating new "chunks" as data is sent to the server.
The other common misconception is that GridFS is the only method for dealing with "files" when sending content to MongoDB. Again in that first sentence, it actually exists as a way to store content that exceeds the 16MB limit for BSON documents.
MongoDB has no problem directly storing binary data in a document as long as the total document does not exceed the 16MB limit. So in most use cases ( small image files used on websites ) the data would be better stored in ordinary documents and thus avoid the overhead of needing to read and write with multiple collections.
So there is no internal server "magic". These are just ordinary collections that you can query, aggregate, mapReduce and even copy or clone.
I was wondering which is better/faster:
Having a separate collection of documents that just contain the image saved as binary data, and possibly some metadata.
Or using GridFS to store the images.
If your images are small you can store them as binary data in the documents in your collection. Just consider that you will be retrieving them every time you query your document (unless you exclude the 'image' field from your queries).
However, if your images are larger I would use GridFS. GridFS has some features that make it very good at handling images that you should consider:
For larger images, when they are stored in GridFs they will be split in chunks and you can store very large files. If you try to store images in your document, you are constrained by the 16Mb max size of a document, and you are consuming space that needs to be used for your actual document.
You can add metadata to the image itself and run queries against these attributes, as if you were doing it from a regular document in a collection. So GridFS is as good as a document for metadata about the image.
I really like that I get MD5 hash calculated on the images. (It is very useful for some of my cases).
By storing images in GridFS you save yourself the preprocessing of the image into binary format (not a big deal, but a convenience of GridFS)
In terms of performance, reading/writing against a regular document should be no different than doing it against GridFS. I would not consider performance to be a differentiator in choosing either one.
My personal recommendation is to go with GridFS, but you need to analyze for your particular use case.
Hope this helps.
I use GridFS to store photos and documents. It's so easy and retrieving it from the collection to display or save locally is easy. You can store metadata along w/ the binary data inside the same collection. This way you don't need to create an additional collection to store them.
For example, in one of my project I store user profile photos along with usernames, file type, and date of upload.
GridFS is developed to handle Files in an efficient way.
http://www.mongodb.org/display/DOCS/When+to+use+GridFS
Do not forget that you maybe will have to translate the data
to a file and back.
But to be sure, do a performance test that takes account of your usage pattern.