实体框架6和导航属性问题

Question

Im hoping to get your help here. Im very new to EF and am having some troubles. I am using the Database First approach and have a database in Azure that I have to retreive data from.

[DataContract]
[Table("A")]
public class AgencyDC
{

    [DataMember]
    [Key]
    public string AID { get; set; }
    public string AName { get; set; }
    public string GeneralEmailAddress { get; set; }
    public string WebsiteURL { get; set; }
    [DataMember]
    [ForeignKey("AID")]
    [IgnoreDataMember]
    public virtual AExtensionDC AExtension { get; set; }
}

[DataContract]
[Table("AExtension")]
public class AExtensionDC
{
    [DataMember]
    [Key]
    public string AID { get; set; }
    [DataMember]
    public bool? IsActive { get; set; }
    public bool? IsOptedOut { get; set; }
    public DateTime? LastUpdated { get; set; }
}

I am trying to use EF6 to retreive my records using DBSets in my context..

public List<ADataCcontract> GetAllAs()
    {
        using (AContext _aCtx = new AContext())
        {                
            var mylist = _aCtx.A.Include("AExtension").ToList();
            return mylist;
        }            
    }

Now, I should be getting back 547 records back with only 1 of them having the AExtension navigational property having content within. The other 546 records should contain NULL. However, for some reason, I am only getting what appears to be a record that has a match in both tables. In SQL speak, I kind of just want a left join so that I return ALL rows from AE entity and OPTIONALLY matches in AE.

I hope this makes sense.

If possible, if you have a fix, could you please post an example I could referent? I am really stuck.

Answer 1

I think this SO Answer might get you most of the way? https://stackoverflow.com/a/4299667/78551

Basically Include does a left outer join or left join as 'outer' is actually optional in SQL.

Answer 2

A left join / inner join will be performed by ´.Include´ if your fields have/lack of nullability.

To review your query put a breakpoint and check this value:

  var myQuery = _aCtx.A.Include("AExtension").ToTraceString();