ember.js - Emberjs conditional output in a template with handlebars -

i got following models:
community name, members , moderators(both users). users, have id , name.

in communitymembers template want show users, , if user moderator, want add saying he's moderator

<script type="text/x-handlebars" data-template-name="communitymembers">   //model contains array of users in community   {{#each user in model}}     <li>{{user.name}}</li>     {{#each moderator in controllers.community.moderators}}       //here problem-->       {{#if moderator.id == user.id}}         <b>this moderator</b>       {{/if}}     {{/each}}   {{/each}} </script> 

i know in handlebars can't use moderator.id==user.id it's easy way want do.

i tried write handlebars helper when checked in helper argument got string saying: "moderator.id" or "user.id" didn't work.

i tried method in community-object:

app.community = ember.object.extend({   ismoderator: function(community, user_id){     return community.moderators.indexof({"id":user_id})!=-1;   } }); 

in template:

{{#if ismoderator(controllers.community,user.id)}}       <h>this moderator</h> {{/if}} 

but gave me errors in template like:

. compiler said: error: parse error on line 12: .../if}}
{{#if ismoderator(controll
----------------------^ expecting 'close', 'close_unescaped', 'string', 'integer', 'boolean', 'id', 'data', 'sep', got 'invalid'

is there knows how deal this?

you can't in handlebars (as said) , shouldn't try mimic behavior helper. this limitation intentionally designed templating, because considered bad practice have logic in template. instead goal should write template this:

<script type="text/x-handlebars" data-template-name="communitymembers">   //model contains array of users in community   {{#each user in controller.userswithmoderatorflag}}     <li>{{user.name}}</li>     {{#if user.ismoderator}}       <b>this moderator</b>     {{/if}}   {{/each}} </script> 

now asking how implement attribute. try (if can't embed attribute user objects):

app.communitymemberscontroller = ember.arraycontroller.extend({   needs : ["community"],   userswithmoderatorflag : function(){     var moderators = this.get("controllers.community.moderators");     return this.get("model").map(function(user){       if(moderators.contains(user)){         user.set("ismoderator", true);       }     }    }.property("model.@each", "controllers.community.moderators.@each") }); 

as can see, it quite easy move logic out of template , controller, belongs.