From 257673e944ce061ee4a7150c1398d1d695546d21 Mon Sep 17 00:00:00 2001
From: timwis <tim@timwis.com>
Date: Wed, 23 Aug 2017 06:33:29 -0400
Subject: [PATCH 1/2] Treat orphan nodes as root nodes

---
 index.js                                 |  8 +++++++-
 package.json                             |  1 +
 test/fixtures/expected-orphan.fixture.js | 15 +++++++++++++++
 test/fixtures/initial-orphan.fixture.js  | 13 +++++++++++++
 test/test.js                             |  8 ++++++++
 5 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 test/fixtures/expected-orphan.fixture.js
 create mode 100644 test/fixtures/initial-orphan.fixture.js

diff --git a/index.js b/index.js
index 8779643..d010139 100644
--- a/index.js
+++ b/index.js
@@ -2,6 +2,7 @@
 var isArray = require('lodash.isarray');
 var assign = require('lodash.assign');
 var property = require('nested-property');
+var keyBy = require('lodash.keyby');
 
 var createTree = function(array, rootNodes, customID) {
   var tree = [];
@@ -25,8 +26,13 @@ var createTree = function(array, rootNodes, customID) {
 };
 
 var groupByParents = function(array, options) {
+  var arrayByID = keyBy(array, options.customID);
+
   return array.reduce(function(prev, item) {
-    var parentID = property.get(item, options.parentProperty) || options.rootID;
+    var parentID = property.get(item, options.parentProperty);
+    if (!parentID || !(parentID in arrayByID)) {
+      parentID = options.rootID;
+    }
 
     if (parentID && prev.hasOwnProperty(parentID)) {
       prev[parentID].push(item);
diff --git a/package.json b/package.json
index 80bedf5..f19864a 100644
--- a/package.json
+++ b/package.json
@@ -35,6 +35,7 @@
   "dependencies": {
     "lodash.assign": "^4.0.6",
     "lodash.isarray": "^4.0.0",
+    "lodash.keyby": "^4.6.0",
     "nested-property": "^0.0.7"
   }
 }
diff --git a/test/fixtures/expected-orphan.fixture.js b/test/fixtures/expected-orphan.fixture.js
new file mode 100644
index 0000000..6ad4fcf
--- /dev/null
+++ b/test/fixtures/expected-orphan.fixture.js
@@ -0,0 +1,15 @@
+module.exports = [{
+  id: 1,
+  parent_id: null,
+  children: [{
+    id: 2,
+    parent_id: 1,
+    children: [{
+      id: 3,
+      parent_id: 2
+    }]
+  }]
+}, {
+  id: 4,
+  parent_id: 5
+}];
diff --git a/test/fixtures/initial-orphan.fixture.js b/test/fixtures/initial-orphan.fixture.js
new file mode 100644
index 0000000..1a497bd
--- /dev/null
+++ b/test/fixtures/initial-orphan.fixture.js
@@ -0,0 +1,13 @@
+module.exports = [{
+  id: 1,
+  parent_id: null
+}, {
+  id: 2,
+  parent_id: 1
+}, {
+  id: 3,
+  parent_id: 2
+}, {
+  id: 4,
+  parent_id: 5
+}];
diff --git a/test/test.js b/test/test.js
index 2d8fcd0..e4308a7 100644
--- a/test/test.js
+++ b/test/test.js
@@ -8,6 +8,8 @@ var customExpected = require('./fixtures/expected-custom.fixture.js');
 var customInitial = require('./fixtures/initial-custom.fixture.js');
 var nestedInitial = require('./fixtures/initial-nested.fixture.js');
 var nestedExpected = require('./fixtures/expected-nested.fixture.js');
+var orphanInitial = require('./fixtures/initial-orphan.fixture.js');
+var orphanExpected = require('./fixtures/expected-orphan.fixture.js');
 
 var current;
 
@@ -89,5 +91,11 @@ describe('array-to-tree', function() {
       expect(current)
         .to.be.deep.equal(nestedExpected);
     });
+    it('should work with orphan nodes', function() {
+      current = toTree(orphanInitial);
+
+      expect(current)
+        .to.be.deep.equal(orphanExpected);
+    });
   });
 });

From 1e1373126ec94ea4b0460eff05edaaf9637ef816 Mon Sep 17 00:00:00 2001
From: timwis <tim@timwis.com>
Date: Wed, 23 Aug 2017 06:38:51 -0400
Subject: [PATCH 2/2] Orphans: use Object.prototype.hasOwnProperty instead of
 in

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index d010139..4d75e21 100644
--- a/index.js
+++ b/index.js
@@ -30,7 +30,7 @@ var groupByParents = function(array, options) {
 
   return array.reduce(function(prev, item) {
     var parentID = property.get(item, options.parentProperty);
-    if (!parentID || !(parentID in arrayByID)) {
+    if (!parentID || !arrayByID.hasOwnProperty(parentID)) {
       parentID = options.rootID;
     }