Call stored function in mongodb

Question

I'm getting some difficulties to call a stored function within mongdb. I'm a little bit newbie with mongo.

[EDIT] : my function stored in mongodb

function() {
    var cndTime = new Date().getTime() - (3600*1000*24*2); // condition
     db.urls.find(needParse: false).forEach(function(item){
        if(item.date < cndTime)  // check
            db.urls.update({_id: item._id}, {$set: { needParse: true }}); // update field
     });
}

All I'm asking is how to invoke this function using reactivemongo or native API.

Answer 1

There is a special system collection named

system.js

that can store JavaScript functions for reuse.

To store a function, you can use the

db.collection.save()

, as in the following examples:

db.system.js.save(
 {
     _id: "echoFunction",
     value : function(x) { return x; }
 }
);

db.system.js.save(
 {
    _id : "myAddFunction" ,
    value : function (x, y){ return x + y; }
 }
);

The _id field holds the name of the function and is unique per database.

The value field holds the function definition.

In the mongo shell, you can use

db.loadServerScripts()

to load all the scripts saved in the system.js collection for the current database. Once loaded, you can invoke the functions directly in the shell, as in the following example:

db.loadServerScripts();

echoFunction(3);

myAddFunction(3, 5);

Source: MONGODB MANUAL

Answer 2

I think you need to use $where for it to work! something like this:

db.urls.find( { needParse: false, $where: function(item){
        if(item.date < cndTime)  // check
            db.urls.update({_id: item._id}, {$set: { needParse: true }});

for more information read this: https://docs.mongodb.com/manual/reference/operator/query/where/

Answer 3

Consider the following example from the mongo shell that first saves a function named echoFunction to the system.js collection and calls the function using db.eval():

db.system.js.save({
    _id: "echoFunction",
    value: function (x) {
        return 'echo: ' + x;
    }
})

db.eval("echoFunction('test')") // -> "echo: test"

echoFunction(...) is available in eval/$where/mapReduce etc. more information is available at http://docs.mongodb.org/manual/tutorial/store-javascript-function-on-server

Answer 4

You can call your function like this

db.loadServerScripts();
db.data.insert({
   _id: myFunction(5),
    name: "TestStudent"
});

if my function is stored in db using command:

db.system.js.save(
 {
  _id : "myFunction" ,
  value : function (x){ return x + 1; }
  });

Answer 5

In the mongo shell, you can use db.loadServerScripts() to load all the scripts saved in the system.js collection for the current database. Once loaded, you can invoke the functions directly in the shell, as in the following example

db.loadServerScripts();

mySampleFunction(3, 5);