Meteor.call回调函数返回未定义

Question

I have this code on the client:

var Checklist = {
            title: this.title,
            belongs_to: this.belongs_to,
            type: this.type,
            items: this.items
        };
        Meteor.call(
            'create_checklist',
            Checklist,
            function(error,result){
                console.log('error',error,'result',result);
                // if(!error) {
                //  Router.go('/checklist/'+response);
                // }
            }
        );

And this on the server:

create_checklist: function(Checklist) {
        Checklists.insert(
            {
                title: Checklist.title,
                belongs_to: Checklist.belongs_to,
                type: Checklist.type,
                items: Checklist.items
            }, function(error,id){
                console.log(error,id);
                if(id) {
                    return id;
                } else {
                    return error;
                }
            }
        );
    },

The Meteor.call passes the information successfully to the server, as the checklist is created. I can see in the server console the ID of the new checklist. However, the client only sees undefined for both error and result.

Answer 1

You don't return result in your server method. You can't return values from callback. Return just result of Checklists.insert:

create_checklist: function(Checklist) {
        return Checklists.insert(
            {
                title: Checklist.title,
                belongs_to: Checklist.belongs_to,
                type: Checklist.type,
                items: Checklist.items
            }, function(error,id){
                console.log(error,id);
                if(id) {
                    return id;
                } else {
                    return error;
                }
            }
        );
    },

According to Meteor docs , insert method returns ID of inserted document.

On the server, if you don't provide a callback, then insert blocks until the database acknowledges the write, or throws an exception if something went wrong.

Answer 2

You don't need to return anything, change the meteor method to this.

create_checklist: function(Checklist) {
        Checklists.insert(
            {
                title: Checklist.title,
                belongs_to: Checklist.belongs_to,
                type: Checklist.type,
                items: Checklist.items
            }
        );
    }

The meteor.call callback know how to handle the server responde thats why you are using error result , if something gets wrong on the method the server will throw an error and the meteor call will fail.

Answer 3

Simplified to the bare minimum:

create_checklist: function(Checklist) {
  return Checklists.insert(Checklist); 
}

Your client code should see the _id of the inserted document in result

I do have to ask though, why ? You should be able to do var id = Checklists.insert(Checklist) on the client if the collection is published and let Meteor handle the synchronization to the server. Is Checklists not published to the client?