feat: Warn users if we do not override helpers in templates

Author: pixelastic

lib/utils.js

@@ -19,6 +19,22 @@ function renderTemplate({template, templateHelpers, data}) {
   var forEach = require('lodash/collection/forEach');
   var content;
 
+  // We add all our template helper methods to the template as lambdas. Note
+  // that lambdas in Mustache are supposed to accept a second argument of
+  // `render` to get the rendered value, not the literal `{{value}}`. But
+  // this is currently broken (see
+  // https://github.com/twitter/hogan.js/issues/222).
+  function addTemplateHelpersToData(templateData) {
+    templateData.helpers = {};
+    forEach(templateHelpers, (method, name) => {
+      data.helpers[name] = () => {
+        return (value) => {
+          return method(hogan.compile(value).render(templateData));
+        };
+      };
+    });
+  }
+
   if (typeof template !== 'string' && typeof template !== 'function') {
     throw new Error('Template must be `string` or `function`');
   }
@@ -28,20 +44,13 @@ function renderTemplate({template, templateHelpers, data}) {
   }
 
   if (typeof template === 'string') {
-    // We add all our template helper methods to the template as lambdas. Note
-    // that lambdas in Mustache are supposed to accept a second argument of
-    // `render` to get the rendered value, not the literal `{{value}}`. But
-    // this is currently broken (see
-    // https://github.com/twitter/hogan.js/issues/222).
-    data.helpers = {};
-    forEach(templateHelpers, (method, name) => {
-      data.helpers[name] = () => {
-        return (value) => {
-          return method(hogan.compile(value).render(data));
-        };
-      };
-    });
-    content = hogan.compile(template).render(data);
+    if (!data.helpers) {
+      data = addTemplateHelpersToData(data);
+    } else {
+      console.warn('TemplateHelpers not included because template data already contained a .helpers key');
+    }
+
+    content = hogan.compile(this.props.template).render(data);
   }
 
   return content;