c# - EF - How to make (composite) foreign key optional -

i have 3 models: order, organisation , orderorganisation.

orderorganisation's existence not mandatory... don't know how tell ef.

currently, if write queries using inner joins instead of outer joins join orderorganisation.

i part of model (if possible) , not in context (as it's large database , think using context fragments logic).

here models.

public class order {     public int id { get; set; }      public virtual icollection<orderorganisation> orderorganisations { get; set; } }  public class organisation {     public int id { get; set; }      public virtual icollection<orderorganisation> orderorganisations { get; set; } }  public class orderorganisation {     [key, column(order = 0)]     public int orderid { get; set; }      [key, column(order = 1)]     public int organisationid { get; set; }      [foreignkey("orderid")]     public virtual order order { get; set; }      [foreignkey("organisationid")]     public virtual organisation organisation { get; set; } } 

what need include please?

i presume need make nullable, can't work out what.

thanks

you not have create cross table on such case on ef. below code enough think

public class order {     public int id { get; set; }      public virtual icollection<organisation> orderorganisations { get; set; } }  public class organisation {     public int id { get; set; }      public virtual icollection<order> orderorganisations { get; set; } } 

then ef create organisationorders named table.