Recently I gave a talk on Automapper in Ottawa .Net Community, so I though I would post the main ideas of the presentation here also.
The demo was based on an Order System where there were just 3 tables/classes, “Order”, “Customer” and “OrderItems”
From the diagram we can see that a Customer has a Bio and if we pull out all the customer from a repository and display it, we may have some of them whom are missing the Bio.
Here is the code of how we are mapping our domain objects to a Dto or ViewModel, we are basically just passing the data to the View to render
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 |
//customer dto public class CustomerDto { public string Bio { get; set; } public string Name { get; set; } } //Controller public ActionResult Index() { var customers = _respository.GetAll(); AutoMapper.Mapper.CreateMap<Customer, CustomerDto>(); var model = AutoMapper.Mapper.Map<IEnumerable<Customer>, IEnumerable<CustomerDto>>(customers); return View(model); } //View <h2>Customers</h2> @foreach (var customer in Model) { <p> @("Name : " + customer.Name) <br /> @("Bio : " + customer.Bio) <br /> </p> } |
Now lets say you want to replace the Null Bio with something like “N/A”, some people may go directly to the razor view code and add that but we can do better with automapper, we can tell automapper that when there is a Null just substitute (i.e NullSubsitution) it with something else, our code would then look like
|
1 2 3 4 5 6 7 8 9 10 |
public ActionResult Index() { var customers = _respository.GetAll(); AutoMapper.Mapper.CreateMap<Customer, CustomerDto>() .ForMember(dest => dest.Bio, opt => opt.NullSubstitute("N/A")); var model = AutoMapper.Mapper.Map<IEnumerable<Customer>, IEnumerable<CustomerDto>>(customers); return View(model); } |
In doing so we will use the same View but now we have “N/A” for “Uncle Leo” bio.
In part2 we will be talking about how to flatten objects by convention.
[…] demo was based on an Order System where there were just 3 tables/classes, “Order”,… [full post] taswar Taswar Bhatti Blog .netautomapper 0 0 0 0 0 […]
[…] Automapper: Mapping objects Part 1 of 7 (NullSubstitution) […]