38 lines
1.2 KiB
Python
38 lines
1.2 KiB
Python
from django.db.models.signals import pre_delete, pre_save
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from django.dispatch import receiver
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from django.utils.translation import gettext_lazy as _
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from .models import Service, ServiceTemplate
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class TemplateLockedError(Exception):
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"""Raised when attempting to modify a locked template."""
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def __init__(self, obj, message=None):
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self.obj = obj
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self.message = message or _(
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"Cannot modify {}: it is locked because one or more services "
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"have been spawned from it."
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).format(obj)
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super().__init__(self.message)
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@receiver(pre_save, sender=ServiceTemplate)
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def lock_service_template_save(sender, instance, **kwargs):
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if not instance.pk:
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return
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if instance.services.exists():
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try:
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old = ServiceTemplate.objects.get(pk=instance.pk)
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except ServiceTemplate.DoesNotExist:
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return
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for field in ("name", "tree"):
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if getattr(instance, field) != getattr(old, field):
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raise TemplateLockedError(instance)
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@receiver(pre_delete, sender=ServiceTemplate)
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def lock_service_template_delete(sender, instance, **kwargs):
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if instance.services.exists():
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raise TemplateLockedError(instance)
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