#8054: Allow replacing default static choices

docs/configuration/optional-settings.md

@@ -174,11 +174,11 @@ EXEMPT_VIEW_PERMISSIONS = ['*']
 
 ## FIELD_CHOICES
 
-Default: Empty dictionary
+Some static choice fields on models can be configured with custom values. This is done by defining `FIELD_CHOICES` as a dictionary mapping model fields to their choices. Each choice in the list must have a database value and a human-friendly label, and may optionally specify a color. (A list of available colors is provided below.)
 
-Some static choice fields on models can be configured with custom values. This is done by defining `FIELD_CHOICES` as a dictionary mapping model fields to their choices list. Each choice in the list must have a database value and a human-friendly label, and may optionally specify a color. (A list of available colors is provided below.)
+The choices provided can either replace the stock choices provided by NetBox, or append to them. To _replace_ the available choices, specify the app, model, and field name separated by dots. For example, the site model would be referenced as `dcim.Site.status`. To _extend_ the available choices, append a plus sign to the end of this string (e.g. `dcim.Site.status+`).
 
-For example, to specify a custom set of choices for the site status field:
+For example, the following configuration would replace the default site status choices with the options Foo, Bar, and Baz:
 
 ```python
 FIELD_CHOICES = {
@@ -190,7 +190,15 @@ FIELD_CHOICES = {
 }
 ```
 
-These will be appended to the stock choices for the field.
+Appending a plus sign to the field identifier would instead _add_ these choices to the ones already offered:
+
+```python
+FIELD_CHOICES = {
+    'dcim.Site.status+': (
+        ...
+    )
+}
+```
 
 The following model field support configurable choices:
 

netbox/utilities/choices.py

@@ -8,12 +8,14 @@ class ChoiceSetMeta(type):
     def __new__(mcs, name, bases, attrs):
 
         # Extend static choices with any configured choices
-        key = attrs.get('key')
-        if key:
-            try:
-                attrs['CHOICES'].extend(settings.FIELD_CHOICES[key])
-            except KeyError:
-                pass
+        replace_key = attrs.get('key')
+        extend_key = f'{replace_key}+' if replace_key else None
+        if replace_key and replace_key in settings.FIELD_CHOICES:
+            # Replace the stock choices
+            attrs['CHOICES'] = settings.FIELD_CHOICES[replace_key]
+        elif extend_key and extend_key in settings.FIELD_CHOICES:
+            # Extend the stock choices
+            attrs['CHOICES'].extend(settings.FIELD_CHOICES[extend_key])
 
         # Define choice tuples and color maps
         attrs['_choices'] = []