Last update: January 30, 2024

Extending cart query with custom parameter

To extend cart queries and incorporate a custom parameter, such as a contract ID:

1. Override the existing cart query type with the extended version and specify a custom query handler:

   services.OverrideQueryType<GetCartQuery, GetCartQueryExtended>().WithQueryHandler<CustomGetCartQueryHandler>();
   

2. Override the ShoppingCartSearchCriteria type to include the extended version:

   AbstractTypeFactory<ShoppingCartSearchCriteria>.OverrideType<ShoppingCartSearchCriteria, ShoppingCartSearchCriteriaExtended>();
   

3. Create an extended version of the GetCartQuery, introducing the ContractId parameter:

   public class GetCartQueryExtended : GetCartQuery
   {
       public string ContractId { get; set; }
   
       public override IEnumerable<QueryArgument> GetArguments()
       {
           foreach (var argument in base.GetArguments())
           {
               yield return argument;
           }
   
           yield return Argument<StringGraphType>(nameof(ContractId));
       }
   
       public override void Map(IResolveFieldContext context)
       {
           base.Map(context);
   
           ContractId = context.GetArgument<string>(nameof(ContractId));
       }
   }
   

4. Implement a custom query handler to handle the extended GetCartQuery:

   public class CustomGetCartQueryHandler : GetCartQueryHandler
   {
       public CustomGetCartQueryHandler(ICartAggregateRepository cartAggregateRepository,
           ICartResponseGroupParser cartResponseGroupParser)
           : base(cartAggregateRepository, cartResponseGroupParser)
       {
       }
   
       // Override the method to include the custom ContractId parameter in the search criteria.
       protected override ShoppingCartSearchCriteria GetCartSearchCriteria(GetCartQuery request)
       {
           var requestExtended = (GetCartQueryExtended)request;
           var criteriaExtended = (ShoppingCartSearchCriteriaExtended)base.GetCartSearchCriteria(request);
   
           criteriaExtended.ContractId = requestExtended.ContractId;
   
           return criteriaExtended;
       }
   }
   

This implementation extends the original GetCartQuery by introducing a GetCartQueryExtended class that includes the additional ContractId parameter. The custom query handler, CustomGetCartQueryHandler, is responsible for handling this extended query and updating the search criteria accordingly.