Inserting a translation into a placeholder with Emblem.js - internationalization

Question

I'm trying to write a login form with ember.js/emblem.js. Everything works, unless I try I18ning the placeholders like so:
Em.TextField valueBinding="view.username" placeholder="#{t 'users.attributes.username}"
Em.TextField valueBinding="view.password" placeholder="#{t 'users.attributes.password'}" type="password"
I get the same response if I try:
= input value=view.username placeholder="#{t 'users.attributes.username}"
= input value=view.password placeholder="#{t 'users.attributes.password'}" type="password"
In both cases, I get this error message:
Pre compilation failed for: form
. . . .
Compiler said: Error: Emblem syntax error, line 2: Expected BeginStatement or DEDENT but "\uEFEF" found. Em.TextField valueBinding="view.username" placeholder="#{t 'users.attributes.username}"
I assume this is happening because I'm trying to compile something from within a statement that's already being compiled. In evidence of this, I don't get the runtime error if I change the code to:
input value=view.username placeholder="#{t 'users.attributes.username}"
input value=view.password placeholder="#{t 'users.attributes.password'}" type="password"
But the downside is that the value bindings no longer work, which still leaves the form nonoperational. Is there another way of approaching this problem that I haven't considered?

Answer 1

As Alexander pointed out, this is a limitation of Ember and Handlebars. The workaround that I've been using is to make the placeholder refer to a controller property which then returns the translated string. For example:
{{input
type="text"
value=controller.filterText
placeholder=controller.filterPlaceholder }}
And then in the controller:
filterPlaceholder: function () {
return i18n.t('players.filter');
}.property('model.name'),

Answer 2

This is beyond the scope of what Emblem can do because it's an inherent limitation of Ember+Handlebars. What you're trying to do is use the input helper and, inside the helper invocation, use another helper t to get the value for the placeholder option. You can't (presently) do this in Ember, so Emblem's not going to be able to do that for you.
edit: you should try the Ember i18n library. I haven't used it yet, but it seems like what you'll want to do is to mix in the TranslateableAttributes mixin into Ember.View, like:
Ember.View.reopen(Em.I18n.TranslateableAttributes)
and then in your emblem template you can do something like
= input placeholderTranslation="button.add_user.title"

Answer 3

I noticed a typo in the first placeholder="#{t 'users.attributes.username}". It's missing the closing single quote.
The Emblem syntax error, line 2: Expected BeginStatement or DEDENT but "\uEFEF" found. can be misleading. I've found that the error is somewhere else entirely to what was being reported. For instance, linkTo without a | for plain text reports a similar error.

Answer 4

You should use the views to format things and drop them into the template. Controllers are not meant to know what happens at the template.
You would also want that to be a property, so i18n will work just once and then you can use the cache version.
Templete:
{{input value=view.username placeholder=view.usernamePlaceholder}}
{{input value=view.password placeholder=view.passwordPlaceholder type="password"}}
View:
export default Ember.View.extend({
usernamePlaceholder: function() {
return Ember.I18n.t('users.attributes.username');
}.property(),
passwordPlaceholder: function() {
return Ember.I18n.t('users.attributes.password');
}.property()
});