From 1b1ddf103edcca815738a1e6a0f92d1f58ed3cbc Mon Sep 17 00:00:00 2001
From: Thomas Rueckstiess <thomas@rueckstiess.net>
Date: Wed, 24 Jun 2015 10:56:17 +1000
Subject: [PATCH] field sort order: _id on top, case-insensitive.

---
 lib/field-collection.js  |  9 +++++++++
 test/field-order.test.js | 26 ++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 test/field-order.test.js

diff --git a/lib/field-collection.js b/lib/field-collection.js
index 6eee95c..c93fff2 100644
--- a/lib/field-collection.js
+++ b/lib/field-collection.js
@@ -4,6 +4,15 @@ var Collection = require('./collection');
  * Container for a list of Fields.
  */
 var FieldCollection = Collection.extend({
+  comparator: function (a, b) {
+    // make sure _id is always at top, even in presence of uppercase fields
+    var aId = a.getId();
+    var bId = b.getId();
+    if (aId === '_id') return -1;
+    if (bId === '_id') return 1;
+    // otherwise sort case-insensitively
+    return (aId.toLowerCase() < bId.toLowerCase()) ? -1 : 1;
+  },
   model: function(attrs, options) {
     return new attrs.klass(attrs, options);
   }
diff --git a/test/field-order.test.js b/test/field-order.test.js
new file mode 100644
index 0000000..9bdd676
--- /dev/null
+++ b/test/field-order.test.js
@@ -0,0 +1,26 @@
+var getSchema = require('../');
+var assert = require('assert');
+var debug = require('debug')('mongodb-schema:test:field-order');
+
+describe('order of fields', function () {
+  it('should have _id fields always at top, even with uppercase fields', function(done) {
+    var docs = [ {FOO: 1, _id: 1, BAR: 1, zoo: 1} ];
+    getSchema('field.order', docs, function (err, schema) {
+      assert.ifError(err);
+      assert.deepEqual(schema.fields.map(function (field) {
+        return field.getId();
+      }), ['_id', 'BAR', 'FOO', 'zoo']);
+      done();
+    });
+  });
+  it('should sort in case-insensitive manner', function (done) {
+    var docs = [ {cb: 1, Ca: 1, cC: 1, a:1, b: 1} ];
+    getSchema('field.order', docs, function (err, schema) {
+      assert.ifError(err);
+      assert.deepEqual(schema.fields.map(function (field) {
+        return field.getId();
+      }), ['a', 'b', 'Ca', 'cb', 'cC']);
+      done();
+    });
+  });
+});