CODEWITHSUNDEEP
meteor
CarbonMan
CarbonMan

Reputation: 4490

Meteor helper not called when Session changes

The following calls messages when the page loads but not when a Session value is changed. Here is the template code;

<head>
  <title>Your welcome to chat</title>
</head>

<body>
    {{> chat}}
</body>

<template name="chat">
    <div class="ui list" style='height: 100px; overflow:scroll;' id='chatHistory'>
        {{> currentChatList}}
    </div>
    <div class="ui large icon input">
        <input type="text" class="field" id="message" placeholder="Type your message here" />
        <i class="comment icon"></i>
    </div>
</template>

<template name="currentChatList">
    {{#each messages}}
    {{/each}}
</template>

Here is the code;

if (Meteor.isClient) {
    Template.chat.events ({
        'keydown input#message' : function (event) {
            if (event.which == 13) { // 13 is the enter key event
                Session.set('time', new Date());
            }
        }
    });
    Template.currentChatList.helpers({
        messages : function () {
            debugger;
            return [];
        }
    });
}

debugger statement is hit when the page loads, but not when the enter key is pressed on the textbox and Session.set('time'..) is executed. I thought a Session value change would cause the template to render.

Upvotes: 2

Views: 457

Answers (3)

Andy
Andy

Reputation: 995

FINALLY THE ANSWER: OMG.

https://blog.meteor.com/the-meteor-chef-reactive-dict-reactive-vars-and-session-variables-971584515a27

I have tried window.someVariableThatChanges = NOT WORKING

I have tried a Session.someVariableThatChanges = NOT WORKING

REACTIVE VARIABLE -- TOTALLY WORKING.

The difference is that you need to create a Template ON CREATED event, add your variables there. Simply use this variable in your even that changes the value, and your helper reference -- it works like magic and feels soooooo goooooood.

Upvotes: 0

Peter Ilfrich
Peter Ilfrich

Reputation: 3816

saimeunt's answer will solve you problem. Your helper at the moment doesn't access any reactive variable (Session or Collection), which means it's never executed again.

Recently more and more people prefer to use reactive-var:

  • The idea is that you declare a reactive variable within your JS file and then USE that reactive variable in your helper. Every time you change the variable, all helpers using this variable are re-executed.

Upvotes: 3

saimeunt
saimeunt

Reputation: 22696

You do not depend on the Session variable you're assigning anywhere on your code. A reactive computation such as template helpers only reruns if one of its dependent reactive data sources is modified, which is clearly not the case in your example.

Try to depend on the Session variable inside your helper code to make it re-execute whenever you press enter.

Template.currentChatList.helpers({
  messages: function () {
    debugger;
    var time = Session.get("time");
    console.log("You pressed enter at",time);
    return [];
  }
});

Upvotes: 1

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