Node appendFile not appending data chunk to file on filesystem - node.js

Question

I have a program that is trying to get the values from the request using curl and store them in a file and serve the stored content back. The decision to store or append the contents in file are based on a query parameter appendFlag
Now when i run this program what i am getting in console is "true" and "appending" This suggests that it indeed reads the flag goes to the if part but somehow the appendFile function is not working.
var http = require('http');
var url = require('url');
var querystring = require('querystring');
var fs = require('fs');
http.createServer(function(request,response){
var str = request.url.split('?')[1];
var query = querystring.parse(str);
var writeStream = fs.createWriteStream(query['fileName']);
console.log("query - ");
console.log(query["appendFlag"]);
request.on('data',function(chunk){
if(query["appendFlag"]=="true"){
console.log("appending");
fs.appendFile(query['fileName'],chunk.toString(),function(err){
if(err) throw err;
});
}else{
var bufferGood = writeStream.write(chunk);
if(!bufferGood) request.pause();
}
});
request.on('end',function(){
response.writeHead(200);
response.write("\n Content with this url is - \n");
var readStream = fs.createReadStream(query['fileName'],{bufferSize:64*1024});
readStream.on('data',function(chunk){
response.write(chunk.toString());
});
readStream.on('end',function(){
response.write("\n");
response.end();
});
});
writeStream.on('drain',function(){
request.resume();
});
}).listen(8080);
Then after reading an answer from SO( How to create appending writeStream in Node.js ) i tried -
// Program to extract url from the request and writing in that particular file
var http = require('http');
var url = require('url');
var querystring = require('querystring');
var fs = require('fs');
http.createServer(function(request,response){
var str = request.url.split('?')[1];
var query = querystring.parse(str);
var writeStream = fs.createWriteStream(query['fileName']);
options = {
'flags': 'a' ,
'encoding' : null,
'mode' : 0666
}
var appendStream = fs.createWriteStream(query['fileName'],[options]);
console.log("query - ");
console.log(query["appendFlag"]);
request.on('data',function(chunk){
if(query["appendFlag"]=="true"){
console.log("appending");
var bufferGood = appendStream.write(chunk.toString());
if(!bufferGood) request.pause();
}else{
var bufferGood = writeStream.write(chunk.toString());
if(!bufferGood) request.pause();
}
});
request.on('end',function(){
response.writeHead(200);
response.write("\n Content with this url is - \n");
var readStream = fs.createReadStream(query['fileName'],{bufferSize:64*1024});
readStream.on('data',function(chunk){
response.write(chunk.toString());
});
readStream.on('end',function(){
response.write("\n");
response.end();
});
});
writeStream.on('drain',function(){
request.resume();
});
}).listen(8080);
That is changed the flag to the 'a' and it also did not append the data?

Answer 1

Your can use your first variant. But before appendFile() you've opened writeStream for the same query["filename"]. The stream is already opened.
var writeStream = fs.createWriteStream(query['fileName']);
options = {
'flags': 'a' ,
'encoding' : null,
'mode' : 0666
}
var appendStream = fs.createWriteStream(query['fileName'],[options]);
May be it's better to do something like:
var options = {
flags: query.appendFile ? 'w' : 'a'
...
Next: why [options]? You should remove the brackets.
Next: there is no guarantee you'll have filename param in querystring. Please handle this situation.