c# - Entity framwork mutiple object relation -

i have table 2 foreignkeys same parent table, edge.startstationid , edge.endstationid.

i trying map theese objets in entity framework, can't find workaround seems fix problem. i've found solutions using 2 collections on parent (station), i'm not interested in.

station (parent) class:

public partial class station {     public station()     {         this.reservations = new list<reservation>();         this.stationmaintenances = new list<stationmaintenance>();     }      public int id { get; set; }      public int typeid { get; set; }     public string title { get; set; }     public string description { get; set; }     public decimal stationlat { get; set; }     public decimal stationlong { get; set; }     public bool isoperational { get; set; }     public bool isactive { get; set; }     public datetime createddate { get; set; }     public virtual batterystorage batterystorages { get; set; }     public virtual list<reservation> reservations { get; set; }     public virtual list<stationmaintenance> stationmaintenances { get; set; }     public virtual list<edge> edges { get; set; }     public virtual stationtype stationtype { get; set; } } 

edge (child) class:

public partial class edge {     public int id { get; set; }     public int startstationid { get; set; }     public virtual station startstation { get; set; }     public int endstationid { get; set; }     public virtual station endstation { get; set; }     public decimal distance { get; set; }     public decimal time { get; set; }     public bool isactive { get; set; } } 

the edge map class, added in onmodelcreating.

public edgemap() {     // primary key     this.haskey(t => t.id);      // properties     // table & column mappings     this.totable("edges");     this.property(t => t.id).hascolumnname("id");     this.property(t => t.startstationid).hascolumnname("startstationid");     this.property(t => t.endstationid).hascolumnname("endstationid");     this.property(t => t.distance).hascolumnname("distance");     this.property(t => t.time).hascolumnname("time");     this.property(t => t.isactive).hascolumnname("isactive");      // relationships     //this.hasoptional(t => t.startstation)     //    .withmany(t => t.edges)     //    .hasforeignkey(d => d.starstationid);     //this.hasoptional(t => t.endstation)     //    .withmany(t => t.edges)     //    .hasforeignkey(d => d.endstationid); } 

exception:

one or more validation errors detected during model generation: system.data.entity.edm.edmassociationtype: : multiplicity conflicts referential constraint in role 'edge_endstation_target' in relationship 'edge_endstation'. because of properties in dependent role non-nullable, multiplicity of principal role must '1'.

i think particular error posted complaining hasoptional. since foreign keys (startstationid , endstationid) non-nullable, it's expecting required mapping. try changing hasrequired, or change type of startstationid , endstationid int? knows navigation properties can null.

as edges collection, should contain? edge references station either startstationid or endstationid values? if so, don't think can single collection.