EF Core: loading related entities - circular dependency - asp.net-core-mvc

Question

I have 2 related entities in EF Core (database first design from an existing database) and having trouble loading one-many relationship - it's a webapi ASP.NET core 1.0 application
Brand Entity
[Table("tblBranding")]
public class Brand {
[Key]
[Column("brandingId")]
public int BrandId { get; set; }
[Column("BrandingActive")]
public bool Active { get; set; }
[JsonIgnore]
[Column("DeadBrand")]
public bool DeadBrand { get; set; }
[Column("BrandingSiteTitle")]
public string Name { get; set; }
//navigation properties
public virtual ICollection<Event> Events { get; set; }
}
Event entity:
[Table("tblEvents")]
public class Event
{
public int EventId { get; set; }
[Column("eventActive")]
public bool Active { get; set; }
[Column("eventName")]
public string Name { get; set; }
public DateTime EventCloseDate {get;set;}
public int PaxAllocationLimit { get; set; }
//navigation properties
[Column("BrandingId")]
public int BrandId { get; set; }
public virtual Brand Brand { get; set; }
public virtual ICollection<Session> Sessions { get; set; }
}
code from for FLUID API in OnModelCreating in DbContext:
modelBuilder.Entity<Event>()
.HasOne(e => e.Brand)
.WithMany(b => b.Events).HasForeignKey(e=>e.BrandId);
public virtual DbSet<Brand> Brands { get; set; }
public virtual DbSet<Event> Events { get; set; }
code from BrandsController:
[HttpGet]
public IActionResult Get() {
//var brands = from b in _context.Brands
// where b.Active == true
// orderby b.BrandName
// select b;
var brands = _context.Brands.Include(e => e.Events).Where(b => b.Active == true).OrderBy(b => b.Name);
return new ObjectResult(brands);
}
code from EventsController
// GET: api/values
[HttpGet("{id:int?}")]
public IActionResult Get(int? id) {
var events = from e in _context.Events
where e.Active == true
orderby e.Name
select e;
if (!events.Any()) {
return HttpNotFound();
}
if (id != null) {
events = events.Where(e => e.EventId == id).OrderBy(e => 0);
if (events.Count() == 0) { return HttpNotFound(); }
return new ObjectResult(events);
}
else {
return new ObjectResult(events);
}
}
When I try to load brands through the API, I get an exception:
Microsoft.Data.Entity.Storage.Internal.RelationalCommandBuilderFactory: Information: Executed DbCommand (80ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT [t].[EventId], [t].[EventCloseDate], [t].[eventActive], [t].[BrandingId], [t].[EventId1], [t].[eventName], [t].[PaxAllocationLimit]
FROM [tblEvents] AS [t]
INNER JOIN (
SELECT DISTINCT [e].[BrandingSiteTitle], [e].[brandingId]
FROM [tblBranding] AS [e]
WHERE [e].[BrandingActive] = 1
) AS [e] ON [t].[BrandingId] = [e].[brandingId]
ORDER BY [e].[BrandingSiteTitle], [e].[brandingId]
Microsoft.Data.Entity.Query.Internal.SqlServerQueryCompilationContextFactory: Error: An exception occurred in the database while iterating the results of a query.
System.Data.SqlClient.SqlException (0x80131904): Invalid column name 'EventId1'.
Apart from this, is there a way to load related entities without using the "Includes" ? If I do not use include and use the standard LINQ query, the related entities are loaded as NULL
UPDATE
I'm now getting an invalid column error - i noticed in my previous code I hadn't used virtual on the ICollection in brand
now i can't figure out why is it generating EventId1 column in the SQL
EF 7 version is 1.0.0-rc1-final
UPDATE-2
After playing around with the code the Exception changed to circular dependency exception in code given the exact same code as above - I don't know why it was generating the invalid column name earlier (EventId1)

Answer 1

Answering my own question here - figured it out-
the 2 entities used here, I've used fully defined relationships in the EF 7
- however the JSON serializer doesn not like that,as this createsa circular dependancy - Brand Contains Events List, and each event also contains the parent brand property -
so the solution here was to add [JsonIgnore] attribute to relationship properties on the child
updated Events class:
[Table("tblEvents")]
public class Event
{
public int EventId { get; set; }
[Column("eventActive")]
public bool Active { get; set; }
[Column("eventName")]
public string Name { get; set; }
public DateTime EventCloseDate {get;set;}
public int PaxAllocationLimit { get; set; }
//navigation properties
[JsonIgnore]
[Column("brandingId")]
public virtual int BrandId { get; set; }
[JsonIgnore]
public virtual Brand Brand { get; set; }
//public virtual ICollection<Session> Sessions { get; set; }
}