but when removing enemy constraints

app/models/item.py

@@ -1,4 +1,4 @@
-from pydantic import BaseModel
+from pydantic import BaseModel, validator
 from typing import List, Optional
 
 from models.attribute import Attribute
@@ -16,6 +16,13 @@ class Item(BaseModel):
     b_param: float = 0.00
     response: Optional[int] = None
 
+    @validator("enemies", pre=True)
+    def set_enemies(cls, v) -> List[id]:
+        if v == "":
+            return []
+        enemies = list(filter(None, [int(enemy) for enemy in v.split(",")]))
+        return enemies
+
     def iif(self, irt_model, theta):
         return ItemInformationFunction(irt_model).calculate(b_param=self.b_param, theta=theta)
 

app/models/problem.py

@@ -8,7 +8,6 @@ from pulp import LpProblem, LpVariable, LpStatus, lpSum
 import logging
 
 from helpers.problem_helper import *
-
 from helpers import service_helper
 
 from models.solution import Solution
@@ -67,8 +66,8 @@ class Problem(BaseModel):
                     logging.info('enemies found, adding constraints...')
 
                     # remove old enemy/sacred constraints
-                    self.problem.constraints.pop('Exclude_enemy_items')
-                    self.problem.constraints.pop('Include_sacred_items')
+                    if 'Exclude_enemy_items' in self.problem.constraints.keys(): self.problem.constraints.pop('Exclude_enemy_items')
+                    if 'Include_sacred_items' in self.problem.constraints.keys(): self.problem.constraints.pop('Include_sacred_items')
 
                     # add constraint to not allow enemy items
                     self.problem += lpSum([