Add a helper method to NPCShopAction to save the inventory properly

main/src/main/java/net/citizensnpcs/trait/CommandTrait.java

@@ -101,19 +101,19 @@ public class CommandTrait extends Trait {
             return Transaction.success();
         if (nonZeroOrNegativeOne(cost) && !player.hasPermission("citizens.npc.command.ignoreerrors.cost")) {
             action = new MoneyAction(cost);
-            if (!action.take(player, null, 1).isPossible()) {
+            if (!action.take(player, 1).isPossible()) {
                 sendErrorMessage(player, CommandTraitError.MISSING_MONEY, null, cost);
             }
         }
         if (experienceCost > 0 && !player.hasPermission("citizens.npc.command.ignoreerrors.expcost")) {
             action = new ExperienceAction(experienceCost);
-            if (!action.take(player, null, 1).isPossible()) {
+            if (!action.take(player, 1).isPossible()) {
                 sendErrorMessage(player, CommandTraitError.MISSING_EXPERIENCE, null, experienceCost);
             }
         }
         if (itemRequirements.size() > 0 && !player.hasPermission("citizens.npc.command.ignoreerrors.itemcost")) {
             action = new ItemAction(itemRequirements);
-            if (!action.take(player, null, 1).isPossible()) {
+            if (!action.take(player, 1).isPossible()) {
                 ItemStack stack = itemRequirements.get(0);
                 sendErrorMessage(player, CommandTraitError.MISSING_ITEM, null, Util.prettyEnum(stack.getType()),
                         stack.getAmount());
@@ -121,26 +121,26 @@ public class CommandTrait extends Trait {
         }
         if (nonZeroOrNegativeOne(command.cost) && !player.hasPermission("citizens.npc.command.ignoreerrors.cost")) {
             action = new MoneyAction(command.cost);
-            if (!action.take(player, null, 1).isPossible()) {
+            if (!action.take(player, 1).isPossible()) {
                 sendErrorMessage(player, CommandTraitError.MISSING_MONEY, null, command.cost);
             }
         }
         if (command.experienceCost != -1 && !player.hasPermission("citizens.npc.command.ignoreerrors.expcost")) {
             action = new ExperienceAction(command.experienceCost);
-            if (!action.take(player, null, 1).isPossible()) {
+            if (!action.take(player, 1).isPossible()) {
                 sendErrorMessage(player, CommandTraitError.MISSING_EXPERIENCE, null, command.experienceCost);
             }
         }
         if (command.itemCost != null && command.itemCost.size() > 0
                 && !player.hasPermission("citizens.npc.command.ignoreerrors.itemcost")) {
             action = new ItemAction(command.itemCost);
-            if (!action.take(player, null, 1).isPossible()) {
+            if (!action.take(player, 1).isPossible()) {
                 ItemStack stack = command.itemCost.get(0);
                 sendErrorMessage(player, CommandTraitError.MISSING_ITEM, null, Util.prettyEnum(stack.getType()),
                         stack.getAmount());
             }
         }
-        return action == null ? Transaction.success() : action.take(player, null, 1);
+        return action == null ? Transaction.success() : action.take(player, 1);
     }
 
     public void clear() {

main/src/main/java/net/citizensnpcs/trait/shop/NPCShopAction.java

@@ -5,6 +5,7 @@ import java.util.function.Consumer;
 import java.util.function.Supplier;
 
 import org.bukkit.entity.Entity;
+import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 
 import com.google.common.collect.Lists;
@@ -12,6 +13,7 @@ import com.google.common.collect.Lists;
 import net.citizensnpcs.api.gui.InventoryMenuPage;
 import net.citizensnpcs.api.persistence.PersistenceLoader;
 import net.citizensnpcs.api.persistence.PersisterRegistry;
+import net.citizensnpcs.util.InventoryMultiplexer;
 
 public abstract class NPCShopAction implements Cloneable {
     @Override
@@ -29,8 +31,32 @@ public abstract class NPCShopAction implements Cloneable {
 
     public abstract Transaction grant(Entity entity, ItemStack[] inventory, int repeats);
 
+    public Transaction grant(Player entity, int repeats) {
+        InventoryMultiplexer im = new InventoryMultiplexer(entity.getInventory());
+        Transaction tx = grant(entity, im.getInventory(), repeats);
+        return Transaction.create(tx::isPossible, () -> {
+            tx.run();
+            im.save();
+        }, () -> {
+            tx.rollback();
+            im.save();
+        });
+    }
+
     public abstract Transaction take(Entity entity, ItemStack[] inventory, int repeats);
 
+    public Transaction take(Player entity, int repeats) {
+        InventoryMultiplexer im = new InventoryMultiplexer(entity.getInventory());
+        Transaction tx = take(entity, im.getInventory(), repeats);
+        return Transaction.create(tx::isPossible, () -> {
+            tx.run();
+            im.save();
+        }, () -> {
+            tx.rollback();
+            im.save();
+        });
+    }
+
     public static interface GUI {
         public InventoryMenuPage createEditor(NPCShopAction previous, Consumer<NPCShopAction> callback);