How can I create an auto increment field on meteor?

Question

How can I create an auto increment field on meteor?

I need an auto increment field, but not for the primary id, it's only to provide an easy to remember case number to the users of a customers support application.

I found this article that explain how to create an auto increment field on mongodb http://docs.mongodb.org/manual/tutorial/create-an-auto-incrementing-field/ but this solutions are not supported on minimongo yet.

How can I implement this feature? I don't care if the solutions skip some consecutive case numbers due to errors, but the case number must be unique.

Is there another approach to generate unique and short case numbers? I don't want to give to the users a case code like this PxyooJWSKc3sMz6Lc, because they must refer to their issues with the case number.

Edit:

Minimong doesn't support findAndModify, so I can't use the first solution listed on the link I posted. The second solution also require methods not available on minimongo.

node.js
mongodb
meteor

Answer 1

Using the mongo-counter package, is posible to create an incrementer with the method incrementCounter(name). The implementation is based on Create an Auto-Incrementing Sequence Field accessing directly the database without going through a Meteor Collection.

Meteor.methods({
    'addRecord':function(doc) {
        doc.id = incrementCounter('docId');
        MyCollection.insert(doc);
        return doc.id;
    }
});

Update

There are new mongo counter packages on Atmosphere, probably better than my initial recommendation.

Answer 2

Well there are a couple of ways you can do this. If you need it to be absolutely consistent you could store the current integer in your collection & use a Meteor.call to add a new record as opposed to doing it from the client.

E.g

Server side js

Meteor.methods({
    'addRecord':function(doc) {
        currentId = MyCollection.findOne({},{sort:{id:-1}}).id || 1;
        doc.id = currentId + 1;
        MyCollection.insert(doc);
        return doc.id;
    }
});

Client side js

doc = {name:"Bob"}
//MyCollection.insert(doc)

//Use this instead
Meteor.call("addRecord", doc, function(err,result) {
    if(result) {
        console.log("Successfully added new record with auto_inc id " + result);
    }
}

Doing it with the Meteor.call you would lose one thing though: latency compensation.

Other possibility

You could store something that is built from a Unix timestamp and shorten it to something more applicable (e.g by cutting off the first few digits):

new Date().getTime().toString().substr(4)

Answer 3

Meteor supports atomic Counters. incrementCounter and decrementCounter can be safely called in concurrent transactions. Both transations would be handled at Mongo DB. It does not go through Meteor's Collection Code hence would be safe to use.

Syntax :-

incrementCounter(name, [amount]) 
decrementCounter(name, [amount]) 
setCounter(name, value)

where name : String; amount : int (default : 1); value : Counter Value

Eg :

Install Counter Package inside your application directory

$ meteor add mrt:mongo-counter

In Server Side

if (Meteor.isServer) {
    console.log("Server Specific Code Starts>>>>>");

    Meteor.methods({
        'getMySequence' : function (sequenceName) {
            var sequence = incrementCounter(sequenceName);
            console.log("Sequence hit : "+sequence);                
            return sequence;
         }
    });

    console.log("Server Specific Code Ends<<<<<");

    }

In Client use below snippet to call the Method :

    Meteor.call('getMySequence', function(err, nextSeq) {
        if (err)
            console.log("Error occurred in Sequence : "+err);
        console.log("Sequence is : "+nextSeq);
    });

Output

On Terminal which acts as Server Side Output Console

? Sequence hit : 14

On Chrome Browser Console which acts as Client Output Console

Sequence is : 14

NOTE : API is only defined for Server End. Create a method in Server and then call it from Client.

All Packages added to your Application are available in packages located inside .meteor folder inside your application

Reference : https://github.com/awwx/meteor-mongo-counter Meteor-Mongo-Counter