ui: Adds a `default` view helper for providing a default value (#4650)

If the first value passed to the helper is an empty string or undefined
then return the second value

ui-v2/app/helpers/default.js

@@ -0,0 +1,10 @@
+import { helper } from '@ember/component/helper';
+
+export function _default(params, hash) {
+  if (params[0] === '' || typeof params[0] === 'undefined') {
+    return params[1];
+  }
+  return params[0];
+}
+
+export default helper(_default);

ui-v2/app/templates/dc/services/show.hbs

@@ -38,7 +38,7 @@
                         href=(href-to 'dc.nodes.show' item.Node.Node)
                         name=item.Node.Node
                         service=item.Service.ID
-                        address=(concat item.Service.Address ':' item.Service.Port)
+                        address=(concat (default item.Service.Address item.Node.Address) ':' item.Service.Port)
                         checks=item.Checks
                     }}
     {{/each}}
@@ -58,7 +58,7 @@
                     data-test-node=item.Node.Node
                     name=item.Node.Node
                     service=item.Service.ID
-                    address=(concat item.Service.Address ':' item.Service.Port)
+                    address=(concat (default item.Service.Address item.Node.Address) ':' item.Service.Port)
                     checks=item.Checks
                     status=item.Checks.[0].Status
                 }}

ui-v2/tests/integration/helpers/default-test.js

@@ -0,0 +1,32 @@
+import { moduleForComponent, test } from 'ember-qunit';
+import hbs from 'htmlbars-inline-precompile';
+
+moduleForComponent('default', 'helper:default', {
+  integration: true,
+});
+
+// Replace this with your real tests.
+test('it renders', function(assert) {
+  this.set('inputValue', '1234');
+
+  this.render(hbs`{{default inputValue}}`);
+
+  assert.equal(
+    this.$()
+      .text()
+      .trim(),
+    '1234'
+  );
+});
+test('it renders the default value', function(assert) {
+  this.set('inputValue', '');
+
+  this.render(hbs`{{default inputValue '1234'}}`);
+
+  assert.equal(
+    this.$()
+      .text()
+      .trim(),
+    '1234'
+  );
+});