Migrating IClientContext
The IClientContext interface was removed as part of removing the XSLT namespace. If you were using this, migrating it requires a few different components as this was not really ported 1-1 in V9.
The following methods shows how to port each method call on the IClientContext to a V9 equivalent.
CurrentProductCatalogGroup
    
    
        clientContext.CurrentProductCatalogGroup
    
    
changes to:
    
    Ucommerce.Search.Models.ProductCatalogGroup store = Ucommerce.Infrastructure.ObjectFactory.Instance.Resolve<Ucommerce.Api.ICatalogContext>().CurrentCatalogGroup;
    
    
GetBasket
    
    
        clientContext.GetBasket(create);
    
    
changes to:
    Ucommerce.EntitiesV2.PurchaseOrder basket = Ucommerce.Infrastructure.ObjectFactory.Instance.Resolve<Ucommerce.Api.ITransactionLibrary>().GetBasket(false);
    
    
IsLoggedIn
    
    
                clientContext.IsLoggedIn
        
    
changes to:
    Ucommerce.EntitiesV2.PurchaseOrder basket = Ucommerce.Infrastructure.ObjectFactory.Instance.Resolve<Ucommerce.Api.ITransactionLibrary>().GetBasket(false);
    
    
CurrentMemberId
    
    
                CurrentMemberId
                
    
changes to:
    string memberId = Ucommerce.Infrastructure.ObjectFactory.Instance.Resolve<Ucommerce.Security.IMemberService>().GetCurrentMember()?.MemberId;
    
    
CurrentMemberName
    
    
                clientContext.CurrentMemberName
        
    
changes to:
    string memberName = Ucommerce.Infrastructure.ObjectFactory.Instance.Resolve<Ucommerce.Security.IMemberService>().GetCurrentMember()?.LoginName;
    
    
IpAddress
    
    
        		clientContext.IpAddress
        
    
changes to:
    string ip = System.Web.HttpContext.Current.Request.UserHostAddress;
    
    
TryGetCustomer
To get the current customer which was previously associated with the IClientContext interface, this has no equivalent in V9.
    
    
        		clientContext.TryGetCustomer()
        		
    
Instead you can try and grab the Customer associated with the member logged in, or the Customer associated with the basket.
    var customerFromLogin = ObjectFactory.Instance.Resolve<IRepository<Customer>>().Select(x => x.MemberId == memberId);
    
    var customerFromBasket = ObjectFactory.Instance.Resolve<IOrderContext>().GetBasket(true).PurchaseOrder.Customer;