Why does my template not reactive? - meteor

Question

If I first open http://localhost:3000/, then click the test link, the roles labels will be displayed.
But if I directly open http://localhost:3000/test(Input the url in Chrome's address bar and hit enter), the roles labels will not be displayed.
Here is my code:
In client startup I subscribe to something:
Meteor.publish("Roles", function(){
return Roles.find();
});
Meteor.startup(function() {
if(Meteor.isClient) {
Meteor.subscribe('Roles');
}
});
And roles template:
Template.roles.helper( {
allRoles: function() {
return Roles.find();
}
})
html
<template name="roles">
<div>
{{#each allRoles}}
<label>test label</label>
{{/each}}
</div>
</template>
The problem is sometime roles template is rendered before the Roles is ready.
So these is no role labels displayed.
But according to Meteor document, helpers is a reactive computation, and Database queries on Collections is reactive data source. So after Roles is ready, the {{#with allRoles}} is reactive and should be displayed.
Why does roles not be displayed?
And then I rewrite my code to:
Meteor.startup(function() {
if(Meteor.isClient) {
roles_sub = Meteor.subscribe('Roles');
}
});
Template.roles.helper( {
allRoles: function() {
console.log(2);
return Roles.find();
},
isReady: function() {
console.log(1);
console.log(roles_sub.ready());
return roles_sub.ready();
}
})
html
<template name="roles">
<div>
{{#if isReady}}
{{#each allRoles}}
<label>test label</label>
{{/each}}
{{/if}}
</div>
</template>
And still role labels cannot be displayed.
And console gives me:
1
false
1
false
1
true
2
Which means isReady() is reactive? but why my roles labels remains blank?
Can somebody explain this?

Answer 1

use Template.subscriptionsReady
server/publish.js
Meteor.publish("Roles", function(){
return Roles.find();
});
client/client.js
Meteor.startup(function() {
Meteor.subscribe('Roles');
});
Template.roles.helpers({ // --> .helper change to .helpers
allRoles: function() {
return Roles.find();
}
})
client/templates.html
<template name="roles">
<div>
{{# if Template.subscriptionsReady }}
{{#with allRoles}}
<label>{{> role }}</label>
{{/with}}
{{ else }}
loading....
{{/if}}
</div>
</template>
<template name="role">
<div>{{ _id }}</div>
</template>
A reactive function that returns true when all of the subscriptions
https://github.com/meteor/meteor/blob/9fe2f4b442ec84eac5352b476d014c977c5ae4a2/packages/blaze/template.js#L424