feat(jexl): add cross-form jexl resolution (#154)

* feat(jexl): add cross-form jexl resolution

This allows specifying cross-form jexl expressing like that:

- "question1"|answer("sub1") // will look for answer to "question1" in child form "sub1"
- "question1"|answer("parent") // will look for answer to "question1" in parent document
- "question1"|answer("parent.sub1") // will look answer to "question1" in sibiling document "sub1"

* Testing

* refactor API: integrate path into question slug

See projectcaluma/caluma#398 (comment)

addon/lib/answer.js

@@ -46,9 +46,7 @@ export default EmberObject.extend({
           this.set(this._valueKey, value);
         }
 
-        next(this, () =>
-          this.document.trigger("valueChanged", this.question.slug, value)
-        );
+        next(this, () => this.field.trigger("valueChanged", value));
 
         return value;
       }

addon/lib/document.js

@@ -1,7 +1,6 @@
 import EmberObject, { computed } from "@ember/object";
 import { assert } from "@ember/debug";
 import { getOwner } from "@ember/application";
-import Evented, { on } from "@ember/object/evented";
 import Field from "ember-caluma/lib/field";
 import jexl from "jexl";
 import { atob } from "ember-caluma/helpers/atob";
@@ -15,7 +14,7 @@ const STATE_PRECEDENCE = ["invalid", "unfinished", "untouched", "valid"];
  *
  * @class Document
  */
-export default EmberObject.extend(Evented, {
+export default EmberObject.extend({
   documentStore: service(),
 
   async init() {
@@ -70,20 +69,44 @@ export default EmberObject.extend(Evented, {
   questionJexl: computed(function() {
     const questionJexl = new jexl.Jexl();
 
-    questionJexl.addTransform("answer", slug => this.findAnswer(slug));
+    questionJexl.addTransform("answer", slugWithPath =>
+      this.findAnswer(slugWithPath)
+    );
 
     return questionJexl;
   }),
 
-  findAnswer(slug) {
-    const result = this.findField(slug);
+  findAnswer(slugWithPath) {
+    const result = this.findField(slugWithPath);
     return result && result.answer.value;
   },
 
-  findField(slug) {
-    // Here it would be possible to extend the search range
-    // over the entire tree by calling findFieldInTree()
-    return this.fields.find(field => field.question.slug === slug);
+  findField(slugWithPath) {
+    const segments = slugWithPath.split(".");
+    const slug = segments.pop();
+    const doc = this.resolveDocument(segments);
+    return doc && doc.fields.find(field => field.question.slug === slug);
+  },
+
+  resolveDocument(segments) {
+    if (!segments) {
+      return this;
+    }
+    let _document = this;
+    for (let segment of segments) {
+      if (segment === "parent") {
+        _document = _document.parentDocument;
+      } else {
+        const formField = _document.fields.find(
+          field => field.question.slug === segment
+        );
+        if (!formField) {
+          return null;
+        }
+        _document = formField.childDocument;
+      }
+    }
+    return _document;
   },
 
   fields: computed(() => []).readOnly(),
@@ -130,14 +153,5 @@ export default EmberObject.extend(Evented, {
     return STATE_PRECEDENCE.find(state =>
       [this.get("childState"), this.get("ownState")].includes(state)
     );
-  }),
-
-  updateHidden: on("valueChanged", "hiddenChanged", function(slug) {
-    const dependentFields = this.fields.filter(field =>
-      field.question.dependsOn.includes(slug)
-    );
-
-    // update hidden state of those fields
-    dependentFields.forEach(field => field.question.hiddenTask.perform());
   })
 });

addon/lib/field.js

@@ -7,6 +7,7 @@ import { camelize } from "@ember/string";
 import { task } from "ember-concurrency";
 import { all } from "rsvp";
 import { validate } from "ember-validators";
+import Evented, { on } from "@ember/object/evented";
 
 import Answer from "ember-caluma/lib/answer";
 import Question from "ember-caluma/lib/question";
@@ -36,7 +37,7 @@ const TYPE_MAP = {
  *
  * @class Field
  */
-export default EmberObject.extend({
+export default EmberObject.extend(Evented, {
   saveDocumentFloatAnswerMutation,
   saveDocumentIntegerAnswerMutation,
   saveDocumentStringAnswerMutation,
@@ -107,6 +108,7 @@ export default EmberObject.extend({
 
     this.setProperties({
       _errors: [],
+      dependentFields: [],
       question,
       answer
     });
@@ -124,6 +126,16 @@ export default EmberObject.extend({
     return `Document:${this.document.id}:Question:${this.question.slug}`;
   }).readOnly(),
 
+  updateHidden: on("valueChanged", "hiddenChanged", function() {
+    this.dependentFields.forEach(field => field.question.hiddenTask.perform());
+  }),
+
+  registerDependentField(field) {
+    if (!this.dependentFields.find(f => f.id === field.id)) {
+      this.dependentFields.push(field);
+    }
+  },
+
   /**
    * Whether the field is valid.
    *

addon/lib/question.js

@@ -3,8 +3,6 @@ import { next } from "@ember/runloop";
 import { lastValue } from "ember-caluma/utils/concurrency";
 import { getAST, getTransforms } from "ember-caluma/utils/jexl";
 import { task } from "ember-concurrency";
-import { assert } from "@ember/debug";
-// import { findFieldInTree } from "ember-caluma/utils/tree";
 
 /**
  * Object which represents a question in context of a field
@@ -43,13 +41,24 @@ export default EmberObject.extend({
           .map(transform => transform.subject.value)
       )
     ];
-    dependents.forEach(slug => {
-      assert(
-        `Field "${slug}" is not present in this document`,
-        this.document.findField(slug)
-      );
+
+    return dependents.map(slugWithPath => {
+      const field = this.document.findField(slugWithPath);
+      if (!field) {
+        if (slugWithPath.includes(".")) {
+          const path = slugWithPath.split(".");
+          const slug = path.pop();
+          throw new Error(
+            `Field "${slug}" is not present in document "${path}"`
+          );
+        }
+        throw new Error(
+          `Field "${slugWithPath}" is not present in this document`
+        );
+      }
+      field.registerDependentField(this.field);
+      return field;
     });
-    return dependents;
   }).readOnly(),
 
   /**
@@ -63,22 +72,18 @@ export default EmberObject.extend({
    * @return {Boolean}
    */
   hiddenTask: task(function*() {
-    let hidden = this.document.fields
-      .filter(field => this.dependsOn.includes(field.question.slug))
-      .some(
-        field =>
-          field.question.hidden ||
-          field.answer.value === null ||
-          field.answer.value === undefined
-      );
+    let hidden = this.dependsOn.some(
+      field =>
+        field.question.hidden ||
+        field.answer.value === null ||
+        field.answer.value === undefined
+    );
 
     hidden =
       hidden || (yield this.field.document.questionJexl.eval(this.isHidden));
 
     if (this.get("hiddenTask.lastSuccessful.value") !== hidden) {
-      next(this, () =>
-        this.document.trigger("hiddenChanged", this.slug, hidden)
-      );
+      next(this, () => this.field.trigger("hiddenChanged"));
     }
 
     return hidden;