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A simple file downlaod function (supports promises via deferred)
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| function download(url, filepath, progressCallback, callback) { | |
| //The deferred object | |
| var deferred = Q.defer(); | |
| http.get(url, function(res) { | |
| //Detecting a redirect the way request/request.js does it | |
| if(res.statusCode >= 300 && res.statusCode < 400 && hasHeader(res, 'location')) { | |
| //Get the new URL and make a fresh call to download, returning the promise | |
| return download(getHeader(res, 'location'), filepath, progressCallback, callback); | |
| } else { | |
| var data = '', totalLength = parseInt(res.getHeader('content-length')); | |
| var file = fs.createWriteStream(filepath); | |
| res.pipe(file); | |
| //Promise fulfilled | |
| res.on('end', function() { | |
| deferred.resolve(filename); | |
| }); | |
| //Promise rejected | |
| res.on('error', function(err) { | |
| deferred.reject(err); | |
| }) | |
| //Progress callback | |
| if(totalLength > 0) { | |
| res.on('data', function() { | |
| data += chunk.toString(); | |
| if(progressCallback === undefined) | |
| progressCallback(data.length / totalLength); | |
| else | |
| //Notifying progress updates using the Promise's progress events | |
| deferred.notify(data.length / totalLength); | |
| }); | |
| } | |
| } | |
| }); | |
| //Register a callback if supplied | |
| deferred.promise.nodeify(callback); | |
| //Finally, return the promise | |
| return deferred.promise; | |
| } |
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