HTML templates

Behavior

  • Templates are automatically recompiled in development when the file is saved; a refresh of the page should be enough to display the latest version. You might need to do a hard refresh, as some browsers cache webpages.
  • Variables can be used in templates. The variables available to the template are called the context. Passing the context to the HTML template sets the values of those variables to the value they were given in the context. The sections below contain specifics on how the context is defined and where it can be found.

Backend

For text generated in the backend, including logged-out ("portico") pages and the webapp's base content, we use the Jinja2 template engine (files in templates/zerver).

The syntax for using conditionals and other common structures can be found here.

The context for Jinja2 templates is assembled from a few places:

  • zulip_default_context in zerver/context_processors.py. This is the default context available to all Jinja2 templates.
  • As an argument in the render call in the relevant function that renders the template. For example, if you want to find the context passed to index.html, you can do:
$ git grep zerver/index.html '*.py'
zerver/views/home.py:    response = render(request, 'zerver/index.html',

The next line in the code being the context definition.

  • zproject/urls.py for some fairly static pages that are rendered using TemplateView, for example:
url(r'^config-error/google$', TemplateView.as_view(
    template_name='zerver/config_error.html',),
    {'google_error': True},),

Frontend

For text generated in the frontend, live-rendering HTML from JavaScript for things like the main message feed, we use the Handlebars template engine (files in static/templates/) and sometimes work directly from JavaScript code (though as a policy matter, we try to avoid generating HTML directly in JavaScript wherever possible).

The syntax for using conditionals and other common structures can be found here.

There's no equivalent of zulip_default_context for the Handlebars templates.

In order to find the context definition, you should grep without using the file extension. For example, to find where invite_subscription.handlebars is rendered, you should run something like this:

$ git grep "render('invite_subscription" 'static/js'
frontend_tests/node_tests/templates.js:    var html = render('invite_subscription', args);
static/js/invite.js:    $('#streams_to_add').html(templates.render('invite_subscription', {streams: streams}));

The second argument to templates.render is the context.

Translation

All user-facing strings (excluding pages only visible to sysadmins or developers) should be tagged for translation.