[Ethereum] How to implement buffer/readable stream in order to add a file to IPFS

ipfsjavascript

I'm trying to upload a file from my directory to IPFS.

Below is what they require from API:

const files = [
  {
    path: '/tmp/myfile.txt',
    content: (Buffer or Readable stream)
  }
]

ipfs.files.add(files, function (err, files) {
  // 'files' will be an array of objects containing paths and the multihashes of the files added
})

I don't understand what they mean by "Buffer or Readable stream." More specifically, I'm not sure how to implement it correctly because I haven't done it before.

What is the difference between "path" and "content"? Why do they need to be separated?

Source: https://github.com/ipfs/js-ipfs/tree/master/examples/ipfs-101

Best Answer

js-ipfs expect you to read the file into a Buffer (an array with data). Did you happen to find docs on https://github.com/ipfs/interface-ipfs-core/blob/master/SPEC/FILES.md#files-api.

You can see how to create a buffer right in the example https://github.com/ipfs/js-ipfs/blob/master/examples/ipfs-101/1.js#L18 or learn how to read a file into a Buffer in the Node.js documentation https://nodejs.org/api/fs.html#fs_fs_readfilesync_path_options

Hope this helps :)

Update: Here is a way to do it

const fs = require('fs')
const files = [
  {
    path: '/tmp/myfile.txt',
    content: fs.readFileSync('/tmp/myfile.txt')
  }
]

ipfs.files.add(files, function (err, files) {
  // 'files' will be an array of objects containing paths and the multihashes of the files added
})

Related Solutions

[Ethereum] How to add a file to IPFS using the API

Read the documentation:

Every command usable from the cli is also available through the HTTP API. For example:

ipfs swarm peers

curl http://127.0.0.1:5001/api/v0/swarm/peers

So for the command:

USAGE ipfs add ... - Add a file to ipfs.

ARGUMENTS

< path >... - The path to a file to be added to IPFS.

https://ipfs.io/docs/commands/#ipfs-add

the equivalent API call would be:

curl -F "image=@/home/bar.jpg" 127.0.0.1:5001/api/v0/add

If you want to use a webpage to upload a document into ipfs it should be something like

<form action="http://127.0.0.1:5001/api/v0/add">
  <input type="file" name="image" accept="image/*">
  <input type="submit">
</form>

[Ethereum] IPFS file download

You can add the npm library 'ipfs' in your DApp.

https://www.npmjs.com/package/ipfs

lib/ipfs.js

const IPFS = require('ipfs');
const node = new IPFS();

 /**
 * Function that uploads file onto IPFS
 * @param {JSON} fileDetails Json containing file details that needs to be 
   updated on IPFS
 * @param {function} callback callback function
 */
const uploadFileToIPFS = function(fileDetails, callback) {
    let fileContent = fs.readFileSync(fileDetails.path);
    node.files.add({
        path: fileDetails.originalname,
        content: fileContent
    }, (err, filesAdded) => {
        if (err) {
            return callback(err);
        }
        callback(null, {
            hash: filesAdded[0].hash
        });
    });
};


/**
 * Function that gets the document contents from IPFS, based on the document's hash
 * @param {String} ipfsHash IPFS hash of the document that is being uploaded onto IPFS
 * @param {function} callback callback function
 */
const getFileContentsFromIPFS = function(ipfsHash, callback) {
    node.files.cat(ipfsHash, function(err, data) {
        callback(err, data);
    });
};

routes/ipfs.js

// API that gets the documents from IPFS
router.get('/api/to/get/document/from/ipfs', function(req, res){
    ipfs.getFileContentsFromIPFS(req.query.ipfsHash, function(err, result){
        if (err) {
            res.json({
                status: 'error',
                message: 'Something went wrong while fetching document from IPFS'
            });
        } else {
            //Get the file type
            let isImageOrPdf = fileType(result);
            if (isImageOrPdf.ext == 'pdf') {
                res.writeHead(200,{
                    'Content-type': 'application/pdf'
                });
                res.end(result);
            } else if(isImageOrPdf.ext == 'png' || isImageOrPdf.ext == 'jpg' ){
                res.writeHead(200, {'Content-Type' : 'image/png'});
                res.end(result);
            }
        }
    });
});

And instead of sending the link, send the ipfsHash of the document and whenever they want to download the file, get the ipfsHash and hit the aboove API and that file will be downloaded.

Best Answer

Related Solutions

[Ethereum] How to add a file to IPFS using the API

[Ethereum] IPFS file download

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