src/Vegasco-Web/src/app/modules/cars/edit-car/edit-car.component.ts

@@ -201,6 +201,14 @@ export class EditCarComponent implements OnInit {
             'Die Anwendung scheint falsche Daten an den Server zu senden.',
         });
         break;
+      case error.status === 409:
+        this.messageService.add({
+          severity: 'warn',
+          summary: 'Konflikt',
+          detail:
+            'Es existiert bereits ein Auto mit diesem Namen. Bitte wähle einen anderen Namen.',
+        });
+        break;
       default:
         console.error(error);
         this.messageService.add({

src/Vegasco.Server.Api/Cars/CreateCar.cs

@@ -1,5 +1,6 @@
 using FluentValidation;
 using FluentValidation.Results;
+using Microsoft.EntityFrameworkCore;
 using Vegasco.Server.Api.Authentication;
 using Vegasco.Server.Api.Common;
 using Vegasco.Server.Api.Persistence;
@@ -19,7 +20,8 @@ public static class CreateCar
 			.WithTags("Cars")
 			.WithDescription("Creates a new car")
 			.Produces<Response>(201)
-			.ProducesValidationProblem();
+			.ProducesValidationProblem()
+			.Produces(409);
 	}
 
 	public class Validator : AbstractValidator<Request>
@@ -59,10 +61,18 @@ public static class CreateCar
 
 		Car car = new()
 		{
-			Name = request.Name,
+			Name = request.Name.Trim(),
 			UserId = userId
 		};
 
+		var isDuplicate = await dbContext.Cars
+			.AnyAsync(x => x.Name.ToUpper() == request.Name.ToUpper(), cancellationToken);
+
+		if (isDuplicate)
+		{
+			return TypedResults.Conflict();
+		}
+
 		await dbContext.Cars.AddAsync(car, cancellationToken);
 		await dbContext.SaveChangesAsync(cancellationToken);
 

src/Vegasco.Server.Api/Cars/UpdateCar.cs

@@ -1,5 +1,6 @@
 using FluentValidation;
 using FluentValidation.Results;
+using Microsoft.EntityFrameworkCore;
 using Vegasco.Server.Api.Authentication;
 using Vegasco.Server.Api.Common;
 using Vegasco.Server.Api.Persistence;
@@ -19,7 +20,8 @@ public static class UpdateCar
 			.WithDescription("Updates a car by ID")
 			.Produces<Response>()
 			.ProducesValidationProblem()
-			.Produces(404);
+			.Produces(404)
+			.Produces(409);
 	}
 
 	public class Validator : AbstractValidator<Request>
@@ -53,7 +55,15 @@ public static class UpdateCar
 			return TypedResults.NotFound();
 		}
 
-		car.Name = request.Name;
+		var isDuplicate = await dbContext.Cars
+			.AnyAsync(x => x.Name.ToUpper() == request.Name.ToUpper(), cancellationToken);
+
+		if (isDuplicate)
+		{
+			return TypedResults.Conflict();
+		}
+
+		car.Name = request.Name.Trim();
 		await dbContext.SaveChangesAsync(cancellationToken);
 
 		Response response = new(car.Id.Value, car.Name);