Introduce JSONEmpty lookup

netbox/extras/lookups.py

@@ -1,4 +1,5 @@
-from django.db.models import CharField, Lookup
+from django.db.models import CharField, JSONField, Lookup
+from django.db.models.fields.json import KeyTextTransform
 
 from .fields import CachedValueField
 
@@ -18,6 +19,30 @@ class Empty(Lookup):
             return f"CAST(LENGTH({sql}) AS BOOLEAN) IS TRUE", params
 
 
+class JSONEmpty(Lookup):
+    """
+    Support "empty" lookups for JSONField keys.
+
+    A key is considered empty if it is "", null, or does not exist.
+    """
+    lookup_name = "empty"
+
+    def as_sql(self, compiler, connection):
+        # self.lhs.lhs is the parent expression (could be a JSONField or another KeyTransform)
+        # Rebuild the expression using KeyTextTransform to guarantee ->> (text)
+        text_expr = KeyTextTransform(self.lhs.key_name, self.lhs.lhs)
+        lhs_sql, lhs_params = compiler.compile(text_expr)
+
+        value = self.rhs
+        if value not in (True, False):
+            raise ValueError("The 'empty' lookup only accepts True or False.")
+
+        condition = 'NOT ' if value else ''
+        sql = f"(NULLIF({lhs_sql}, '') IS {condition}NULL)"
+
+        return sql, lhs_params
+
+
 class NetHost(Lookup):
     """
     Similar to ipam.lookups.NetHost, but casts the field to INET.
@@ -45,5 +70,6 @@ class NetContainsOrEquals(Lookup):
 
 
 CharField.register_lookup(Empty)
+JSONField.register_lookup(JSONEmpty)
 CachedValueField.register_lookup(NetHost)
 CachedValueField.register_lookup(NetContainsOrEquals)

netbox/extras/models/customfields.py

@@ -603,8 +603,12 @@ class CustomField(CloningMixin, ExportTemplatesMixin, ChangeLoggedModel):
         if lookup_expr is not None:
             kwargs['lookup_expr'] = lookup_expr
 
+        # 'Empty' lookup is always a boolean
+        if lookup_expr == 'empty':
+            filter_class = django_filters.BooleanFilter
+
         # Text/URL
-        if self.type in (
+        elif self.type in (
                 CustomFieldTypeChoices.TYPE_TEXT,
                 CustomFieldTypeChoices.TYPE_LONGTEXT,
                 CustomFieldTypeChoices.TYPE_URL,