Move field validation to model, for API compatibility

src/servala/core/forms.py

@@ -1,5 +1,4 @@
 from django import forms
-from django.core.exceptions import ValidationError
 from django.utils.translation import gettext_lazy as _
 
 from servala.core.models import ControlPlane
@@ -40,35 +39,31 @@ class ControlPlaneAdminForm(forms.ModelForm):
     def clean(self):
         cleaned_data = super().clean()
 
-        # Get the three credential fields
         ca_data = cleaned_data.get("certificate_authority_data")
         server = cleaned_data.get("server")
         token = cleaned_data.get("token")
 
-        # Check if any of the fields are filled
-        has_ca = bool(ca_data)
-        has_server = bool(server)
-        has_token = bool(token)
-
-        # If some but not all fields are filled, raise validation error
-        if (has_ca or has_server or has_token) and not (
-            has_ca and has_server and has_token
-        ):
-            raise ValidationError(
-                _(
-                    "All credential fields (certificate authority data, server, and token) must be provided together or left empty."
-                )
-            )
-
-        # If all fields are filled, create the api_credentials JSON
-        if has_ca and has_server and has_token:
+        if ca_data and server and token:
             cleaned_data["api_credentials"] = {
                 "certificate-authority-data": ca_data,
                 "server": server,
                 "token": token,
             }
         else:
-            cleaned_data["api_credentials"] = {}
+            if not (ca_data or server or token):
+                cleaned_data["api_credentials"] = {}
+            else:
+                # Some fields are filled but not all - validation will fail at model level,
+                # as model field validators are also called by the API.
+                # We still create the JSON with whatever we have so the model validator can run.
+                credentials = {}
+                if ca_data:
+                    credentials["certificate-authority-data"] = ca_data
+                if server:
+                    credentials["server"] = server
+                if token:
+                    credentials["token"] = token
+                cleaned_data["api_credentials"] = credentials
 
         return cleaned_data
 

src/servala/core/models/service.py

@@ -1,3 +1,4 @@
+from django.core.exceptions import ValidationError
 from django.db import models
 from django.utils.translation import gettext_lazy as _
 from encrypted_fields.fields import EncryptedJSONField
@@ -63,14 +64,34 @@ class Service(models.Model):
         return self.name
 
 
+def validate_api_credentials(value):
+    """
+    Validates that api_credentials either contains all required fields or is empty.
+    """
+    # If empty dict, that's valid
+    if not value:
+        return
+
+    # Check for required fields
+    required_fields = ("certificate-authority-data", "server", "token")
+    missing_fields = required_fields - set(value)
+
+    if missing_fields:
+        raise ValidationError(
+            _("Missing required fields in API credentials: %(fields)s"),
+            params={"fields": ", ".join(missing_fields)},
+        )
+
+
 class ControlPlane(models.Model):
     name = models.CharField(max_length=100, verbose_name=_("Name"))
     description = models.TextField(blank=True, verbose_name=_("Description"))
     k8s_api_endpoint = models.URLField(verbose_name=_("Kubernetes API endpoint"))
-    # TODO: schema
+    # Either contains the fields "certificate_authority_data", "server" and "token", or is empty
     api_credentials = EncryptedJSONField(
         verbose_name=_("API credentials"),
         help_text="Required fields: certificate-authority-data, server (URL), token",
+        validators=[validate_api_credentials],
     )
 
     cloud_provider = models.ForeignKey(