I am new to programming and trying to experiment a bit, still struggling with the best way to access mongoDB from within my code. I've seen a few posts here on stack overflow but they more or less all require that the code required to load mongo is included in each and every .js file. I would like to avoid that in order to keep the code for accessing my DB in only one file.
Note that I am using the "mongo-factory" module.
Would the code below be acceptable?
I've created what I would call a "producer" of database objects, database.js
var mongoFactory = require('mongo-factory');
function Database(close,callback) {
mongoFactory.getConnection(<connection string>).then(function (database) {
callback(database.db(<db name>));
if(close) database.close();
}).catch(function (err) {
console.error(err);
});
}
module.exports = Database;
Then when I want to access the database from any of my files I could do the below, avoiding to introduce db-specific parameters and the mongo-factory requirement in here:
var Database = require('./database');
var callback_actOnDatabase = function (db) {
db.collection..... do something here
};
var d = new Database(false, callback_actOnDatabase);
instead of mongo-factoy use mongoose module to connect the database,model declaration also we dont intalise the db parameters again,please go through the link
https://www.npmjs.com/package/mongoose
Related
I am new to Meteor. I am using following code to read a file stored at server.
Client side
Meteor.call('parseFile', (err, res) => {
if (err) {
alert(err);
} else {
Session.set("result0",res[0]);
Session.set("result1",res[1]);
Session.set("result2",res[2]);
}
});
let longitude = Session.get("result0");
let latitude = Session.get("result1");
var buildingData = Session.get("result2");
Server Side
Meteor.methods({
'parseFile'() {
var csv = Assets.getText('buildingData.csv');
var rows = Papa.parse(csv).data;
return rows;
}
})
The problem is while I make a call it takes time to send the result back and hence wherever i am using latitude and longitude its giving undefined and page breaks. So, is there any solution to avoid this problem. One of the solution can be to make a synchronous call and wait for result to be returned.
You can make the server method run synchronously using the futures package, which should force the client to wait for the method to complete.
It might look something like this:
Meteor.methods({
'parseFile'() {
var future = new Future();
var csv = Assets.getText('buildingData.csv');
var rows = Papa.parse(csv).data;
future.return(rows);
future.wait();
}
});
This would require you installing the futures package linked above and setting up your includes properly in file containing your Meteor.methods() definitions. You might also look into good error handling inside your method.
UPDATE:
The link to the Future package is an NPM package, which you can read about here. The link above is to the atmosphere package, which looks like an old wrapper package.
Due to some existing mongodb structure. I cant use Meteors Meteor.user. So when I try to insert new user calcMD5 says is not defined. How do I convert Md5 in meteor server? I dont know weather my approach is good or not. correct me if am wrong.
if (Meteor.isServer) {
newUser: function(email, password){
Users.insert({"emailid":email,"password":calcMD5(password)});
}
});
Here the template code
Template.signInWithEmail.events({
'click .btn-create-account': function(event, template) {
email = $('[name="emailAddress"]').val();
password = $('[name="password"]').val();
//Create new user
Meteor.call("newUser", email, password, function(error, result) {});
}
Problem is, the calcMD5 function does not exist in Meteor as it is. (nor JavaScript, nor NodeJS) I will assume you want to use this library or another one for your project.
If you want to be able to use an external library, you have to first add it into your Meteor project. You can do this by simply putting the javascript file in a folder such as server/lib/.
Or, if this gets too complicated, just add the crypto-md5 meteor package using:
meteor add jparker:crypto-md5
and call CryptoJS.MD5(password) instead of your calcMD5(password) function call.
I'm trying to set up mongodb on Windows 8 using node.js, Does anyone know why im getting this error. C:\users\phill\node_modules\mongodb\lib\mongodb\mongo_client.js:359 it also says at collection = db collection,,, can't call method 'collection' of null. I'm having a hard time setting it up. My goal is to be able to add to mongo db, and see that I add or pull up what I added, but adding something is good enough for me for now. I'm trying every thing I can find, even straight from the website, I tried everything I see on here as well. Think it maybe it's the way I have things set up. My node.js is saved in my c: drive there is a file that says, program files(86x) in there I have node_modules, npm and such. The path ends up being, computer > windows (C:) > program files(86x) > nodejs. My Mongodb is saved right on my C: drive the path end up being windows (C:) > mongodb-win32-x86_64-2008plus-2.4.8. In my C: I also created a file data and in it created another db. I have been told i should just use mongoose, I'm just learning so i open to any advice, links or anything that will help. I have one last question as well, i learned php and then found out about sql injections and stuff like that, i am not seeing anything about security at all, should i expect the same as well. For this i get text not defined, but i have been getting errors with everthing i have done, best i did was get stuck on a right concern screen.
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect("mongodb://localhost:27017/integration_test", function(err, db) {
test.equal(null, err);
test.ok(db != null);
db.collection("replicaset_mongo_client_collection").update({a:1},
{b:1}, {upsert:true}, function(err, result) {
test.equal(null, err);
test.equal(1, result);
db.close();
test.done();
});
});
Tried this as well and getting a error,C:\users\phill\node_modules\mongodb\lib\mongodb\mongo_client.js:359.... at collection = db collection,,, can't call method 'collection' of null. im calling it in command prompt node filename.js I'm saving it where my node.js file is, I have pulled up files before and created a server.
var Db = require('mongodb').Db,
MongoClient = require('mongodb').MongoClient,
Server = require('mongodb').Server,
ReplSetServers = require('mongodb').ReplSetServers,
ObjectID = require('mongodb').ObjectID,
Binary = require('mongodb').Binary,
GridStore = require('mongodb').GridStore,
Grid = require('mongodb').Grid,
Code = require('mongodb').Code,
BSON = require('mongodb').pure().BSON,
assert = require('assert');
var db = new Db('test', new Server('localhost', 27017));
// Fetch a collection to insert document into
db.open(function(err, db) {
var collection = db.collection("simple_document_insert_collection_no_safe");
// Insert a single document
collection.insert({hello:'world_no_safe'});
// Wait for a second before finishing up, to ensure we have written the item to disk
setTimeout(function() {
// Fetch the document
collection.findOne({hello:'world_no_safe'}, function(err, item) {
assert.equal(null, err);
assert.equal('world_no_safe', item.hello);
db.close();
})
}, 100);
});
In your first code example, you said:
For this i get text not defined
I assume you meant "test not defined?" Your script only requires the mongodb library, and I don't believe test is a core nodejs function, so that would explain the error.
To reference the driver documentation for db.collection(), an assert library is used, but also properly imported (as you did in your second example).
Within your callback to db.open(), you don't check if an error occurred. That might shed some light on why db is null in that function.
Regarding your question about the equivalent of SQL injection with MongoDB, the main areas of concern are places where you might pass untrusted input into evaluated JavaScript, or using such input to construct free-form query objects (not simply using a string, but more like dropping an object into your BSON query). Both of these links should provide more information on the subject:
What type of attacks can be used vs MongoDB?
How does MongoDB address SQL or Query injection?
I'm working on a NoDB CMS in Meteor, but I'm new to both Meteor and JavaScript frameworks.
How do I go about reading and writing files to the server?
Within the Node fs module you have a writeFile function.
getUser = Meteor.users.findOne({_id : Meteor.userId()});
userObject = JSON.stringify(getUser);
var path = process.env["PWD"] + "/public/";
fs.writeFile(process.env["PWD"] + "/public/"+Meteor.userId()+'.txt', userObject,
function (err) {
if (err) throw err;
console.log('Done!');
}
);
The above snippet would create a file with all the information of the user. You could access the properties of the result of your query with something like getUser._id to prepare your data parameter (String or Buffer) to print pretty.
All this of course is server side.
you can try to use Npm.require inside the startup function. Like so
Meteor.startup(function () {
fs = Npm.require('fs');
}
But you should definitely have a look at collectionFS that does what you are looking for: storing files on the server and allowing you to retrieve them
an added advantage is that you can distribute everything over many nodes of a MongoDB cluster
to manipulate image files, you can use imagemagick with nodejs this should allow you to transform in any way you need.
The node fs module is a start. http://nodejs.org/api/fs.html
You might want to be a bit more specific with your question though, as it's kind of broad.
The quick overview is this: for my web app I can write most of my functionality using CouchApp and CouchDB views, etc. I love the feature of CouchApp that pushes my code up to the server via replication- this makes the deployment cycle very easy.
However, to do some arbitrary work not supported in couchdb and works around a few limitations, I need to put a web platform in front of CouchDB. I'm considering building this in node.js because it uses JavaScript and I want to continue the easy deployment method of pushing code into the database.
Here's how i imagine it working:
- I write a web server/service in node.js using the normal method and the node command to start it.
- this sevice connects to couch db and gets a virtual list and a URL mapping list. This list is stored in redis for quick lookup. This list will tell the server, when it gets a request, based on host and path, etc, which handler is to be run.
- the server fetches the handler- which is just a document, it could be a design document or an arbitrary json document in couchdb. And then executes that handler to handle the request, as if I'd writte the handler as part of node js.
So the question is, how to get a son data structure that contains a JavaScript function in it, in text form, and execute that function?
This may be blindingly obvious, but i come from a compiled background, so normally there would be a compilation step here that makes this pretty much impossible.
So, what I'm thinking is in pseudo code:
Var string thecode = getValueForMapKey(handlerFunctionIWant);
somehowmagicallyexecute(thecode)
Is there an exec or run function that will do the magical execution step above in JavaScript?
It will run in the node.js context.
You can also use it in node, like this, as a dynamic function:
var cradle = require('cradle');
var db = new(cradle.Connection)().database('db_name');
db.get('_design/node%2Fyour_code', function (err, doc) {
if (!err){
var your_code = new Function(doc['arguments'].join(','), doc.code);
your_code("cool", "also cool");
}else{
console.error('error:', err);
}
});
make your docs look like this:
{
"_id": "_design/node/your_code",
"arguments": [
"nameOfArg1",
"nameOfArg2"
],
"code": "console.log('arg1', nameOfArg1); console.log('arg2', nameOfArg2);"
}
It's in the same scope as where the new Function is called, so you have access to cradle, or you can require other libs, which will be loaded as if it was an anon function in that scope.
Put it in a design doc, then only admin can make changes, out of the box.
Here is a nicer, but similar approach:
// Format, in db:
doc = {
"_id": "_design/node",
"your_function_name": {
"arguments": [
"nameOfArg1",
"nameOfArg2"
],
"code": "console.log('arg1', nameOfArg1); console.log('arg2', nameOfArg2);"
},
"your_other_function_name": {
"arguments": [
"name"
],
"code": "console.log('hello', name, 'how\\'s it going, bro?');"
}
};
var cradle = require('cradle');
var db = new(cradle.Connection)().database('db_name');
function run_from_db(name, args){
db.get('_design/node', function (err, doc) {
if (!err){
if (doc[name] !== undefined){
var fn = new Function(doc[name]['arguments'].join(','), doc[name].code);
fn.apply(fn, args);
}else{
console.error("could not find", name, "in _design/node");
}
}else{
console.error(err);
}
});
}
run_from_db('your_other_function_name', ['konsumer']);
this will output:
hello konsumer how's it going, bro?
eval(handlerFunctionIwant) is the call to execute it. You need to make sure that there's no way for hackers to inject code into that string, of course.
It is not clear to me if this will evaluate it in a context that has access to other javescript resources, such as the rest of node.js or access to your couchdb library.