javascript - How to use Meteor methods inside of a template helper

Question

How can I define a Meteor method which is also callable in a template helper?

I have these two files:

file: lib/test.js

Meteor.methods({
    viewTest : function (str) {
        return str;
    }
});

file: client/myView.js

Template.helloWorld.helpers({
    txt : function () {
        var str = Meteor.call('viewTest', 'Hello World.');
        return str;
    }
});

When I give "str" a normal string everything works fine. But in this case my template does not get any value. I defined - for the test - in the same file where the method is a normal function and tried to call the function. The error I got was that the function does not exist. So I think that Meteor tries to render the template before it knows anything about the methods I defined for it. But I think that this is a bit unusual - isn't it?

question from:https://stackoverflow.com/questions/22147813/how-to-use-meteor-methods-inside-of-a-template-helper

Answer 1

There is now a new way to do this (Meteor 0.9.3.1) which doesn't pollute the Session namespace

Template.helloWorld.helpers({
    txt: function () {
        return Template.instance().myAsyncValue.get();
    }
});

Template.helloWorld.created = function (){
    var self = this;
    self.myAsyncValue = new ReactiveVar("Waiting for response from server...");
    Meteor.call('getAsyncValue', function (err, asyncValue) {
        if (err)
            console.log(err);
        else 
            self.myAsyncValue.set(asyncValue);
    });
}

In the 'created' callback, you create a new instance of a ReactiveVariable (see docs) and attach it to the template instance.

You then call your method and when the callback fires, you attach the returned value to the reactive variable.

You can then set up your helper to return the value of the reactive variable (which is attached to the template instance now), and it will rerun when the method returns.

But note you'll have to add the reactive-var package for it to work

$ meteor add reactive-var