feat(form): pass form and root form as context for jexl expressions

addon/lib/document.js

@@ -95,6 +95,12 @@ export default EmberObject.extend({
     }
   ),
 
+  rootDocument: computed("parentDocument.rootDocument", function() {
+    if (!this.parentDocument) return null;
+
+    return this.parentDocument.rootDocument || this.parentDocument;
+  }),
+
   questionJexl: computed(function() {
     const questionJexl = new jexl.Jexl();
 
@@ -109,6 +115,18 @@ export default EmberObject.extend({
     return questionJexl;
   }),
 
+  questionJexlContext: computed(
+    "raw.form.slug",
+    "rootDocument.raw.form.slug",
+    function() {
+      return {
+        rootForm: this.rootDocument
+          ? this.rootDocument.raw.form.slug
+          : this.raw.form.slug
+      };
+    }
+  ),
+
   findAnswer(slugWithPath) {
     const field = this.findField(slugWithPath);
     if (!field || !field.answer) {

addon/lib/question.js

@@ -78,7 +78,11 @@ export default EmberObject.extend({
       );
 
     hidden =
-      hidden || (yield this.field.document.questionJexl.eval(this.isHidden));
+      hidden ||
+      (yield this.field.document.questionJexl.eval(
+        this.isHidden,
+        this.field.document.questionJexlContext
+      ));
 
     if (this.get("hiddenTask.lastSuccessful.value") !== hidden) {
       next(this, () => this.field.trigger("hiddenChanged"));
@@ -114,6 +118,12 @@ export default EmberObject.extend({
             (field.answer.value === null || field.answer.value === undefined))
       );
 
-    return hidden || !(yield this.document.questionJexl.eval(this.isRequired));
+    return (
+      hidden ||
+      !(yield this.document.questionJexl.eval(
+        this.isRequired,
+        this.field.document.questionJexlContext
+      ))
+    );
   })
 });

tests/unit/lib/document-test.js

@@ -158,4 +158,30 @@ module("Unit | Library | document", function(hooks) {
       );
     }
   });
+
+  test("computes the correct root document", async function(assert) {
+    assert.expect(3);
+
+    const level1 = this.nestedDocument;
+    const level2 = this.nestedDocument.childDocuments[0];
+    const level3 = this.nestedDocument.childDocuments[0].childDocuments[0];
+
+    assert.equal(level3.rootDocument.id, level1.id);
+    assert.equal(level2.rootDocument.id, level1.id);
+    assert.equal(level1.rootDocument, null);
+  });
+
+  test("computes the correct jexl context", async function(assert) {
+    assert.expect(3);
+
+    const level1 = this.nestedDocument;
+    const level2 = this.nestedDocument.childDocuments[0];
+    const level3 = this.nestedDocument.childDocuments[0].childDocuments[0];
+
+    const rootForm = level1.raw.form.slug;
+
+    assert.deepEqual(level3.questionJexlContext, { rootForm });
+    assert.deepEqual(level2.questionJexlContext, { rootForm });
+    assert.deepEqual(level1.questionJexlContext, { rootForm });
+  });
 });

tests/unit/lib/question-test.js

@@ -157,4 +157,29 @@ module("Unit | Library | question", function(hooks) {
 
     this.question1.field.off("hiddenChanged", handler);
   });
+
+  test("form and rootForm can be used in jexl expressions", async function(assert) {
+    assert.expect(4);
+
+    const rootDocument = this.nestedDocument;
+    const document = rootDocument.childDocuments[0].childDocuments[0];
+    const question = document.fields[0].question;
+
+    const trueExpression = `rootForm == '${rootDocument.raw.form.slug}'`;
+    const falseExpression = "rootForm == 'thisisalsonottheslug'";
+
+    question.setProperties({
+      isHidden: trueExpression,
+      isRequired: trueExpression
+    });
+    assert.equal(await question.hiddenTask.perform(), true);
+    assert.equal(await question.optionalTask.perform(), false); // optional is inverted required!
+
+    question.setProperties({
+      isHidden: falseExpression,
+      isRequired: falseExpression
+    });
+    assert.equal(await question.hiddenTask.perform(), false);
+    assert.equal(await question.optionalTask.perform(), true); // optional is inverted required!
+  });
 });