The ability to attach `attrs` when embedding widgets

app/assets/javascripts/discourse/widgets/header-contents.js.es6

@@ -4,10 +4,10 @@ import hbs from 'discourse/widgets/hbs-compiler';
 createWidget('header-contents', {
   tagName: 'div.contents.clearfix',
   template: hbs`
-    {{attach widget="home-logo"}}
+    {{attach widget="home-logo" attrs=attrs}}
     <div class="panel clearfix">{{yield}}</div>
     {{#if attrs.topic}}
-      {{attach widget="header-topic-info"}}
+      {{attach widget="header-topic-info" attrs=attrs}}
     {{/if}}
   `,
 });

lib/javascripts/widget-hbs-compiler.js.es6

@@ -1,11 +1,30 @@
 function resolve(path) {
   if (path.indexOf('settings') === 0) {
     return `this.${path}`;
-  } else if (path.indexOf('parentState') === 0) {
-    return `attrs._${path}`;
+  }
+  return path;
 }
 
-  return path;
+function sexp(value) {
+  if (value.path.original === "hash") {
+
+    let result = [];
+
+    value.hash.pairs.forEach(p => {
+      result.push(`"${p.key}": ${p.value.original}`);
+    });
+
+    return `{ ${result.join(", ")} }`;
+  }
+}
+
+function argValue(arg) {
+  let value = arg.value;
+  if (value.type === "SubExpression") {
+    return sexp(arg.value);
+  } else if (value.type === "PathExpression") {
+    return value.original;
+  }
 }
 
 function mustacheValue(node, state) {
@@ -13,8 +32,14 @@ function mustacheValue(node, state) {
 
   switch(path) {
     case 'attach':
-      const widgetName = node.hash.pairs.find(p => p.key === "widget").value.value;
-      return `this.attach("${widgetName}", state ? $.extend({}, attrs, { _parentState: state }) : attrs)`;
+      let widgetName = node.hash.pairs.find(p => p.key === "widget").value.value;
+
+      let attrs = node.hash.pairs.find(p => p.key === "attrs");
+      if (attrs) {
+        return `this.attach("${widgetName}", ${argValue(attrs)})`;
+      }
+      return `this.attach("${widgetName}", attrs)`;
+
       break;
     case 'yield':
       return `this.attrs.contents()`;

script/test_hbs_compiler.rb

@@ -0,0 +1,28 @@
+template = <<~HBS
+  {{attach widget="widget-name" attrs=attrs}}
+  {{#if state.category}}
+    {{attach widget="category-display" attrs=(hash category=state.category)}}
+  {{/if}}
+HBS
+
+ctx = MiniRacer::Context.new(timeout: 15000)
+ctx.eval("var self = this; #{File.read("#{Rails.root}/vendor/assets/javascripts/babel.js")}")
+ctx.eval(File.read(Ember::Source.bundled_path_for('ember-template-compiler.js')))
+ctx.eval("module = {}; exports = {};");
+ctx.attach("rails.logger.info", proc { |err| puts(err.to_s) })
+ctx.attach("rails.logger.error", proc { |err| puts(err.to_s) })
+ctx.eval <<JS
+console = {
+  prefix: "",
+  log: function(msg){ rails.logger.info(console.prefix + msg); },
+  error: function(msg){ rails.logger.error(console.prefix + msg); }
+}
+
+JS
+source = File.read("#{Rails.root}/lib/javascripts/widget-hbs-compiler.js.es6")
+ctx.eval(source)
+
+js_source = ::JSON.generate(template, quirks_mode: true)
+
+puts ctx.eval("exports.compile(#{js_source})");
+

test/javascripts/widgets/widget-test.js.es6

@@ -188,7 +188,7 @@ widgetTest('widget attaching', {
 
     createWidget('attach-test', {
       tagName: 'div.container',
-      template: hbs`{{attach widget="test-embedded"}}`
+      template: hbs`{{attach widget="test-embedded" attrs=attrs}}`
     });
   },