diff --git a/buisnesslogic/src/main/java/com/plannaplan/entities/Exchange.java b/buisnesslogic/src/main/java/com/plannaplan/entities/Exchange.java
index 785c681..c0830c4 100644
--- a/buisnesslogic/src/main/java/com/plannaplan/entities/Exchange.java
+++ b/buisnesslogic/src/main/java/com/plannaplan/entities/Exchange.java
@@ -18,7 +18,7 @@ public class Exchange {
     private Long id;
 
     @OneToOne
-    @JoinColumn(name = "owned_id")
+    @JoinColumn(name = "owned_id", unique = true)
     private Assignment ownedAssignment;
    
     @OneToOne
diff --git a/buisnesslogic/src/main/java/com/plannaplan/services/ExchangeService.java b/buisnesslogic/src/main/java/com/plannaplan/services/ExchangeService.java
index a2f6556..cd31023 100644
--- a/buisnesslogic/src/main/java/com/plannaplan/services/ExchangeService.java
+++ b/buisnesslogic/src/main/java/com/plannaplan/services/ExchangeService.java
@@ -24,6 +24,12 @@ public class ExchangeService {
         return this.repo.save(exchange);
     }
 
+    
+    /** 
+     * @param assignment Assignment to trade for
+     * @param group Desired group
+     * @return Optional with Exchange if exist
+     */
     public Optional<Exchange> checkForExchange(Assignment assignment, Groups group){
         return this.repo.checkForExchange(assignment, group);
     }
diff --git a/restservice/src/main/java/com/plannaplan/controllers/ExchangeController.java b/restservice/src/main/java/com/plannaplan/controllers/ExchangeController.java
index e9a032c..b9c4869 100644
--- a/restservice/src/main/java/com/plannaplan/controllers/ExchangeController.java
+++ b/restservice/src/main/java/com/plannaplan/controllers/ExchangeController.java
@@ -69,9 +69,8 @@ public class ExchangeController extends TokenBasedController{
 
         final Assignment assignmentInstance = assignment.get();
         final Groups groupInstance = group.get();
-        final Optional<Exchange> exchangeInstance = this.exchangeService.checkForExchange(assignmentInstance, groupInstance);
 
-        if(!(assignmentInstance.getCommision().getCommisionOwner().getId() == asker.getId() && assignmentInstance.isAccepted() && exchangeInstance.isEmpty())){
+        if(!(assignmentInstance.getCommision().getCommisionOwner().getId().equals(asker.getId()) && assignmentInstance.isAccepted())){
             return new ResponseEntity<>("Some of problems appeared. Check if you have access to given assignment and if it is accepted or the exchange has not been already added.", HttpStatus.BAD_REQUEST);
         }