Styjun

I'm using EF Core 2.2
the Code with the error

var ClientCase= _context.Client_Cases.Include(a=>a.Case_Sessions). FirstOrDefault(x => x.Id == id);

The Error

System.Data.SqlClient.SqlException: 'Invalid column name
'Client_CaseId'. Invalid column name 'Case_LevelId'. Invalid column
name 'Client_CaseId'. Invalid column name 'Court_CircleId'. Invalid
column name 'Court_HallId'.'

Entities

1- Parent Client_Case

public class Client_Cases

 [Key]
 [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
 public long Id get; set; 
 public string Opponent get; set; 
 public DateTime? StartDate get; set; 
 public DateTime Recieve_Date get; set; 
 [ForeignKey("Clients")]
 public long? ClientID get;set;
 public Clients Client get; set; 
 [ForeignKey("Case_Levels")]
 public long? LevelID get; set; 
 public virtual Case_Levels Case_Levels get; set; 
 [ForeignKey("Case_Types")]
 public long? TypeID get; set; 
 public virtual Case_Types Case_Types get; set; 
 [ForeignKey("Court_Circles")]
 public long? CircleID get; set; 
 public virtual Court_Circles Court_Circles get; set; 
 [ForeignKey("Court_Halls")]
 public long? HallID get; set; 
 public virtual Court_Halls Court_Halls get; set; 
 [ForeignKey("Courts")]
 public long? CourtID get; set; 
 public virtual Courts Court get; set; 
 [ForeignKey("Case_Status")]
 public long? StatusID get; set; 
 public Case_Status Case_Status get; set; 
 [ForeignKey("Lawyers")]
 public long? LawyerID get; set; 
 public virtual LawyersData Lawyers get; set; 
 public string Description get; set; 
 public string Code get; set; 
 public string CaseNo get; set; 
 public List<Case_Sessions> Case_Sessions get; set; 

Detail Entity Case_Session

public class Case_Sessions

 [Key]
 [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
 public long Id get; set; 
 [ForeignKey("Client_Cases")]
 public long? CaseID get;set;
 public Client_Cases Client_Case get; set; 
 [ForeignKey("Case_Levels")]
 public long? LevelID get; set; 
 public Case_Levels Case_Level get; set; 
 [ForeignKey("Court_Circles")]
 public long? CircleID get; set; 
 public Court_Circles Court_Circle get; set; 
 [ForeignKey("Court_Halls")]
 public long? HallID get; set; 
 public Court_Halls Court_Hall get; set; 
 [ForeignKey("Case_Status")]
 public long? StatusID get; set; 
 public Case_Status Case_Status get; set; 
 public DateTime Session_Date get; set; 
 public string Judge_Name get; set; 
 public string Session_Result get; set; 
 public string Notes get; set; 

if I get the parent without include the child it works
if I get the detail it works

I know the error that EF Core Create its own naming convention for the Foreign keys
but I think the tag Foreign Key override that naming convention

Now where I am wrong?

Thank You

[ForeignKey("")] Mean? name the property you have added in class to become a foreign key. e.g:

public long? CaseID get;set;
[ForeignKey("CaseID")]
public Client_Cases Client_Case get; set; 

public long? CircleID get; set; 
[ForeignKey("CircleID")]
public Court_Circles Court_Circle get; set; 

You can use annotations like above, In your case, below correction needed:

[ForeignKey("Client")] // it should be [ForeignKey("Client")] not an extra s if you using entities name in annotation.
 public long? ClientID get;set;
 public Clients Client get; set; 

this should be your relationship for lawyer:

[ForeignKey("Lawyers")]
 public long? LawyersID get; set; 
 public virtual LawyersData Lawyers get; set; 

I am assuming that the type of primary key in LawyersData table is long?.