ASP.NET WebApi JSON Response and Entities with foreign key

Question

I'm working on WebApi project and I have 2 entities in my domain:
Street

public class Street
{
  public int ID { get; set; }
  public string Name { get; set; }
  public int StreetTypeID { get; set; }
  public virtual StreetType StreetType { get; set; }
}

and StreetType:

public class StreetType
{
  public int ID { get; set; }
  public string Name { get; set; }
  public virtual ICollection<Street> Streets { get; set; }
}

I use FluenApi to map these entities:

public class StreetTypeMap : EntityTypeConfiguration<StreetType>
{
  public StreetTypeMap()
  {
     HasKey(t => t.ID);
     Property(t => t.ID).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
     Property(t => t.Name).IsRequired().HasMaxLength(50);
     HasMany(a => a.Streets).WithRequired(p => p.StreetType).HasForeignKey(p => p.StreetTypeID);
     ToTable("StreetType");
   }
 }

and the similar for Street entity.
Now I get JSON:

{
  "id":1,
  "name":"Street1",
  "streettypeid":3
}

How can I get the JSON like:

{
  "id":1,
  "name":"Street1",
  "streettypeid":
   {
    "id":3,
    "name":"Type3"
   }
}

Or some similar structure. How can I accomplish this in .NET?

My Controller:

StreetController : BaseApiController<Street>

and

    public class BaseApiController<T> : ApiController where T : BaseEntity
    {
        protected UnitOfWork unitOfWork = new UnitOfWork();

        protected IRepository<T> repository;

        public BaseApiController()
        {
            repository = unitOfWork.EFRepository<T>();
        }
        public virtual IQueryable<T> Get()
        {
          var entity = repository.Table;

          if (entity == null)
          {
              throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.NoContent));
          }
          return entity;
      }

}

Roman Marusyk · Accepted Answer · 2015-07-28 23:10:54Z

2

To preserve object references in JSON, add the following code to Application_Start method in the Global.asax file:

var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling = 
    Newtonsoft.Json.PreserveReferencesHandling.All;

For more datail please read this article.

Another way is try to use OData in your webapi. You have to install the OData Packages:

Install-Package Microsoft.AspNet.Odata

Then you'll able yo use $expand that causes related entities to be included inline in the response.
You can leave all as is, but I think it will properly to add IgnoreDataMember (do not forget add using System.Runtime.Serialization;)

public class StreetType
{
  public int ID { get; set; }
  public string Name { get; set; }
  [IgnoreDataMember]
  public virtual ICollection<Street> Streets { get; set; }
}

Also need to add attribute to you Get method:

[EnableQuery]
public virtual IQueryable<T> Get()

After that you can create http-request like:

http://blablabla/Street?$expand=StreetType

and get all Streets with their StreetType

edited Jul 28, 2015 at 23:10

answered Jul 28, 2015 at 21:06

Roman Marusyk

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4 Comments

user5166592 Over a year ago

Thank you. Whili I try it I got an error: Could not find a property named 'StreetTypes' on type 'Domain.Entities.Street'."

Roman Marusyk Over a year ago

Which http-request do you use?

Roman Marusyk Over a year ago

Ok, why $expand=StreetTypes? There is no property with the name StreetTypes. In your Street class exists public virtual StreetType StreetType { get; set; }. So, you have to use http://mysite/Street?$expand=StreetType

user5166592 Over a year ago

Oh, yes, you are exactly right. I am very inattentive. Thanks its working!!! Thank you very much. You really help me. Thanks. It was the best simple solution

Stephen Brickner · Accepted Answer · 2015-07-28 21:22:13Z

1

You need to create a view model to return that has the included entity.

Edit: here's a complete api controller method including proposed route.

    [HttpGet, Route("/api/streets/{id:int:min(1)}")]
    public IHttpActionResult GetYourJsonData(int id)
    {
        try
        {
            //from your unit of work class
            return uow.GetEntities<Street>(x => x.ID == id)
                .FirstOrDefault()
                .Select(viewModel => new {
                    ID = viewModel.ID,
                    Name = viewModel.Name,
                    StreetTypeID = viewModel.StreetType //consider renaming this to streeytype and not street type id
                });
        }
        catch(Exception)
        {
             return InternalServerError();
        }
    }



//Edit: in your repo class
public IEnumerable<T> GetEntities<T>(Func<T, bool> predicate) where T : class
{
    return yourContext.Set<T>().Where(predicate);
}

edited Jul 28, 2015 at 21:22

answered Jul 28, 2015 at 20:09

Stephen Brickner

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10 Comments

user5166592 Over a year ago

Thanks but I can not use dbContext in my controller because there is implemented pattern UnitOfWork and I do not have dbContext

Stephen Brickner Over a year ago

Can you update your question to show what you are using to get data then? Ultimately it will be the same, the data context part will just move inside of your repository that is exposed by your unit of work.

user5166592 Over a year ago

My UnitOfWork is not work with concrete entity. UnitOfWork work with dbcontext: IDbSet<TEntity> Set<TEntity>() where TEntity : BaseEntity

Stephen Brickner Over a year ago

Then you just need to add a predicate. I updated my answer to show you what you'll need to do in your repo.

Stephen Brickner Over a year ago

No problem, I've updated my answer to show you how you would use it.

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