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I’m trying to use MongoDB server-side JavaScript in my nodejs/node-mongodb-native project and just interested how could I save my custom functions in global context of MongoDB and get access to them from db.eval script?
Let’s say I have the following unit function:
var myDocumentUtils = {
doStuff: function (doc) {
// do stuff with doc ...
return doc;
}
}
And I have the following JavaScript function stored in db.system.js collection:
function processDocument (id) {
var doc = db.myCollection.findOne({ _id : ObjectId(id)});
doc = myDocumentUtils.doStuff(doc); // need access to global myDocumentUtils object
db.myCollection.save(doc);
return doc;
};
I execute processDocument function from my nodejs application like the following:
db.eval('processDocument(54382cb3233283cd3331ca1d)', function (err, doc) {
if (err) throw err;
});
So my question is how to save myDocumentUtils in global MongoDB V8 context to be accessible in db.eval function?
Answer
Add the second parameter to processDocument as below:
function processDocument (id, myDocumentUtils) {
var doc = db.myCollection.findOne({ _id : ObjectId(id)});
doc = myDocumentUtils.doStuff(doc); // need access to global myDocumentUtils object
db.myCollection.save(doc);
return doc;
};
Then write db.eval() like this way:
db.eval(function() {
return processDocument.apply(this, arguments);
}, "54382cb3233283cd3331ca1d", myDocumentUtils);
For your environment, you can add the call back just behind the last parameter myDocumentUtils.
APPEND ———————
store below tow functions into db.system.js :
function getMyDocumentUtils() {
return myDocumentUtils = {
doStuff: function (doc) {
// do stuff with doc ...
return doc;
}
};
}
function processDocument (id) {
var doc = db.myCollection.findOne({ _id : ObjectId(id)});
var myDocumentUtils = getMyDocumentUtils(); // added line
doc = myDocumentUtils.doStuff(doc); // need access to global myDocumentUtils object
db.myCollection.save(doc);
return doc;
};
Then call db.eval() as your original style.