From 3066bb9340d038de56c6ba483d5e854a8222cb31 Mon Sep 17 00:00:00 2001
From: frank <frank@server-wizard.com>
Date: Thu, 30 May 2024 07:44:26 -0700
Subject: [PATCH] When merging config, union arrays instead of replacing them.

---
 Changelog.md        |  3 +++
 README.md           | 14 +++++++++-----
 package-lock.json   |  2 +-
 package.json        |  2 +-
 src/merge-config.ts |  4 +++-
 5 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/Changelog.md b/Changelog.md
index 1600be2..8efd968 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,3 +1,6 @@
+## 1.0.3 / 2024-05-30
+* When merging config, union arrays (instead of right replacing left).
+
 ## 1.0.2 / 2024-05-27 (No functional changes)
 * Improve index.ts
 
diff --git a/README.md b/README.md
index 8aacd8d..64dffbf 100644
--- a/README.md
+++ b/README.md
@@ -151,11 +151,15 @@ See `discoverInitializers` and `invokeInitializers` for more info.
 
 ## Implementation Notes
 lodash.merge is used for configuration merging (along with lodash.set if you are merging at a key prefixed merge point).  
-Understanding how lodash.merge actually works is important, so please read [its documentation](https://lodash.com/docs/#merge).  Once you understand it,
-you will see a problem...
-* How do I replace an object or an array of values?
-
-This library actually uses [lodash.mergeWith](https://lodash.com/docs/#mergeWith) in order to implement a "not" ability (aka `!`, aka _bang_, aka _replacement_).  
+Understanding how lodash.merge actually works is important, so please read [its documentation](https://lodash.com/docs/#merge).  
+Once you understand it,
+you will see a problem that this library uses  [lodash.mergeWith](https://lodash.com/docs/#mergeWith) to address...
+* How do I merge two arrays (instead of having the left array replaced by the right).
+* How do I replace an object (as opposed to merging it)?
+
+To address the first, we use lodash.union to 'merge' arrays which is (IMO) the intuitive behavior. 
+If you really did want to replace the left arry with the right, you can us the 'not' feature described next.  
+To address the second, we implement a "not" ability (aka `!`, aka _bang_, aka _replacement_).  
 This feature allows you to **overwrite** a node in the hierarchy instead of merging.
 ```json5
 // Merging in this json5 override will "merge" the values into configuration,
diff --git a/package-lock.json b/package-lock.json
index 5871d56..7f09b20 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
 	"name": "dyflex-config",
-	"version": "1.0.2",
+	"version": "1.0.3",
 	"lockfileVersion": 2,
 	"requires": true,
 	"packages": {
diff --git a/package.json b/package.json
index db288af..6eb9457 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "dyflex-config",
-	"version": "1.0.2",
+	"version": "1.0.3",
 	"description": "Simple, dynamic, flexible, configuration library.",
 	"author": "Frank Stock",
 	"license": "MIT",
diff --git a/src/merge-config.ts b/src/merge-config.ts
index 426639c..1a332a9 100644
--- a/src/merge-config.ts
+++ b/src/merge-config.ts
@@ -1,4 +1,4 @@
-import {get as lodashGet, mergeWith as lodashMergeWith, set as lodashSet} from 'lodash';
+import {get as lodashGet, mergeWith as lodashMergeWith, set as lodashSet, union as lodashUniton} from 'lodash';
 
 /**
  * A unique marker used as the default value for lodashGet.
@@ -33,6 +33,8 @@ export function mergeConfig<T extends object>(dst: T, src: object, mergePoint?:
 			});
 			object[key.substring(1)] = srcValue;
 		}
+		else if (Array.isArray(objValue))
+			return lodashUniton(objValue, srcValue);
 		return undefined;
 	});
 	deletes.forEach(d => d());