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[feature] Allow zero subnets in SubnetDivisionRuleFix/allow zero subnets #1287

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[feature] Allow zero subnets in SubnetDivisionRuleFix/allow zero subnets #1287

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e27d40b
[fix] Auto-fill organization from master subnet in SubnetDivisionRule
peterishakvr12 Mar 14, 2026
1d81dd8
[fix] Fix indentation and use organization_id
peterishakvr12 Mar 14, 2026
cfffbcb
[fix] Use organization_id consistently to avoid DB queries
peterishakvr12 Mar 14, 2026
ba15b67
[feature] Allow zero subnets in SubnetDivisionRule
peterishakvr12 Mar 16, 2026
34b545a
[fix] Fix unterminated string in number_of_subnets help_text
peterishakvr12 Mar 16, 2026
bf61fef
[fix] Remove duplicate fields and fix help_text
peterishakvr12 Mar 16, 2026
1f309d1
[tests] Update test to allow zero subnets
peterishakvr12 Mar 16, 2026
efb189f
[tests] Update test to allow zero subnets
peterishakvr12 Mar 16, 2026
105a232
Merge branch 'master' into fix/allow-zero-subnets
nemesifier Mar 16, 2026
a3c6540
[tests] Fix indentation and line length
peterishakvr12 Mar 17, 2026
5231d5c
[fix] Fix indentation in test
peterishakvr12 Mar 17, 2026
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15 changes: 13 additions & 2 deletions openwisp_controller/subnet_division/base/models.py
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Original file line number Diff line number Diff line change
Expand Up @@ -35,8 +35,12 @@ class AbstractSubnetDivisionRule(TimeStampedEditableModel, OrgMixin):
)
number_of_subnets = models.PositiveSmallIntegerField(
verbose_name=_("Number of Subnets"),
help_text=_("Indicates how many subnets will be created"),
validators=[MinValueValidator(1)],
help_text=_(
"Indicates how many subnets will be created. "
"Set to 0 to assign IP addresses directly "
"from the main subnet.
),
validators=[MinValueValidator(0)],
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@coderabbitai coderabbitai bot Mar 16, 2026

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⚠️ Potential issue | 🟠 Major

Allowing 0 here still conflicts with non-zero subnet assumptions in validation.

Line [43] enables number_of_subnets=0, but current validators still enforce child-subnet assumptions (_validate_master_subnet_consistency and _validate_ip_address_consistency). This can reject valid zero-subnet scenarios or validate against the wrong target subnet size.

💡 Suggested alignment for zero-subnet mode 
diff --git a/openwisp_controller/subnet_division/base/models.py b/openwisp_controller/subnet_division/base/models.py
@@
-        available = 2 ** (self.size - master_subnet.prefixlen)
-        # Account for the reserved subnet
-        available -= 1
-        if self.number_of_subnets >= available:
+        available = 2 ** (self.size - master_subnet.prefixlen)
+        # Account for the reserved subnet only when subnets are requested
+        available -= 1
+        if self.number_of_subnets > 0 and self.number_of_subnets >= available:
             raise ValidationError(
@@
     def _validate_ip_address_consistency(self):
         try:
-            next(
-                ip_network(str(self.master_subnet.subnet)).subnets(new_prefix=self.size)
-            )[self.number_of_ips - 1]
+            target_subnet = ip_network(str(self.master_subnet.subnet))
+            if self.number_of_subnets > 0:
+                target_subnet = next(target_subnet.subnets(new_prefix=self.size))
+            target_subnet[self.number_of_ips - 1]
         except IndexError:
             raise ValidationError(
                 {
                     "number_of_ips": _(
                         f"Generated subnets of size /{self.size} cannot accommodate "
                         f"{self.number_of_ips} IP Addresses."
                     )
                 }
             )
🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@openwisp_controller/subnet_division/base/models.py` at line 43, The model
currently allows number_of_subnets=0 via validators=[MinValueValidator(0)] but
the validation methods _validate_master_subnet_consistency and
_validate_ip_address_consistency assume at least one subnet and therefore reject
or miscompute zero-subnet cases; fix by either tightening the field validator to
MinValueValidator(1) if zero should be disallowed, or (preferable for
zero-subnet support) keep MinValueValidator(0) and update
_validate_master_subnet_consistency and _validate_ip_address_consistency to
early-return (no-op) when self.number_of_subnets == 0 so they skip child-subnet
checks and avoid referencing a non-existent target subnet size.

)
Comment thread
coderabbitai[bot] marked this conversation as resolved.
size = models.PositiveSmallIntegerField(
verbose_name=_("Size of subnets"),
Expand Down Expand Up @@ -69,6 +73,13 @@ def rule_class(self):
return import_string(self.type)

def clean(self):
# Auto-fill organization from master subnet
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🧹 Nitpick | 🔵 Trivial

Remove redundant inline comment in clean().

The comment at Line [76] repeats what the code already makes clear and can be dropped for cleaner readability.

As per coding guidelines, "Avoid unnecessary comments or docstrings for code that is already clear."

🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@openwisp_controller/subnet_division/base/models.py` at line 76, Remove the
redundant inline comment inside the clean() method (the comment that states
"Auto-fill organization from master subnet") since it simply repeats what the
code does; delete that comment line from the clean() function in models.py and
leave the implementation unchanged to improve readability.

if (
self.master_subnet_id
and self.master_subnet.organization_id is not None
and not self.organization_id
):
self.organization_id = self.master_subnet.organization_id
super().clean()
self._validate_label()
self._validate_master_subnet_validity()
Expand Down
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