Fixed recursion issues

Added InvenTreeTree base class

InvenTree/part/models.py

@@ -1,18 +1,28 @@
 from __future__ import unicode_literals
 
 from django.db import models
+from django.core.exceptions import ObjectDoesNotExist
 
-class PartCategory(models.Model):
-    name = models.CharField(max_length=100)
-    description = models.CharField(max_length=250)
-    parent = models.ForeignKey('self', on_delete=models.CASCADE, blank=True, null=True)
+class InvenTreeTree(models.Model):
     
-    def __str__(self):
-        if self.parent:
-            return "/".join([p.name for p in self.path]) + "/" + self.name
-        else:
-            return self.name
+    # Return a flat set of all child items under this node
+    def getUniqueChildren(self, unique=None):
         
+        if unique is None:
+            unique = set()
+        
+        if self.id in unique:
+            return unique
+        
+        unique.add(self.id)
+            
+        children = PartCategory.objects.filter(parent = self.id)
+        
+        for child in children:
+            child.getUniqueChildren(unique)
+            
+        return unique
+    
     # Return the parent path of this category
     @property
     def path(self):
@@ -22,6 +32,39 @@ class PartCategory(models.Model):
             return []
         
         return parent_path
+    
+    # Custom SetAttribute function to prevent parent recursion
+    def __setattr__(self, attrname, val):
+        # Prevent parent from being set such that it would cause a recursion loop
+        if attrname == 'parent_id':
+            # Parent cannot be set to same ID (this would cause looping)
+            if val == self.id:
+                return
+            # Null parent is OK
+            elif val is None:
+                pass
+            # Ensure that the new parent is not already a child 
+            else:
+                kids = self.getUniqueChildren()
+                if val in kids:
+                    print("ALREADY A CHILD")
+                    return
+                
+        super(InvenTreeTree, self).__setattr__(attrname, val)
+    
+    class Meta:
+        abstract = True
+
+class PartCategory(InvenTreeTree):
+    name = models.CharField(max_length=100)
+    description = models.CharField(max_length=250)
+    parent = models.ForeignKey('self', on_delete=models.CASCADE, blank=True, null=True)
+    
+    def __str__(self):
+        if self.parent:
+            return "/".join([p.name for p in self.path]) + "/" + self.name
+        else:
+            return self.name
         
 class Part(models.Model):
     name = models.CharField(max_length=100)