Xtykutl

I have the following model:

[Table("Facts")]

public partial class Facts

{

  [Key]

  public Guid ID { get; set; }

  public Guid UserID { get; set; }

  [ForeignKey(nameof(UserID))]

  public Users Users { get; set; }

  //other properties are ommitted

}

Its migration code:

migrationBuilder.CreateTable(

            name: "Facts",

            columns: table => new

            {

                ID = table.Column<Guid>(nullable: false),

                UserID = table.Column<Guid>(nullable: false),

            //other properties are ommitted

            },

            constraints: table =>

            {

                table.PrimaryKey("PK_Facts", x => x.ID);

                table.ForeignKey(

                    name: "FK_Facts_Users_UserID",

                    column: x => x.UserID,

                    principalTable: "Users",

                    principalColumn: "ID",

                    onDelete: ReferentialAction.Cascade);

            });

As it has a navigation property, I set it to an existing ID (it is required).

This is the saving method:

 public async Task SaveData<T>(List<T> data, bool isNew) where T : class

 {

   if (data == null)

      throw new ArgumentNullException(nameof(data));

   try

   {

     if (isNew)

       context.Set<T>().AddRange(data);

     else

     {

       context.Set<T>().AttachRange(data);

       data.ForEach(d => (context as DbContext).Entry(d).State = EntityState.Modified);

     }

     await context.SaveChangesAsync();

   }

   catch (Exception ex)

   {       

     throw;

   }

 }

When I enter the save method, I have the following state (the ID is set, the navigation property object is null):

After AddRange, I have the following state (the ID is set, the navigation property object is not null):

Inside the catch, I get the following exception:

Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred
while updating the entries. See the inner exception for details. --->
Microsoft.Data.Sqlite.SqliteException: SQLite Error 19: 'FOREIGN KEY
constraint failed'

It looks like it tries to add the navigation property object as a new item to the database.

How can I prevent the reinsert of the already existing navigation property?

UPDATE

After enabling the SQL logging, I get the following information (@p0 is the PK, @p18 is the FK):

Failed executing DbCommand (105ms) [Parameters=[@p0='84ddca86-3f8a-41f1-aaed-2c65bd1cb384' (DbType = String),...@p18='e33f7939-bc35-4d82-b68b-e1cc0cf32ff1' (DbType = String)...]

INSERT INTO "Facts" ("ID", ... "UserID",...)

      VALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7, @p8, @p9, @p10, @p11, @p12, @p13, @p14, @p15, @p16, @p17, @p18, @p19, @p20, @p21, @p22, @p23, @p24, @p25, @p26, @p27, @p28, @p29);

Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 19: 'FOREIGN KEY constraint failed'.

UPDATE2

I made some emulator testing and I found out the following.

The data of Users table is inserted initially via a SQL script, with the following code:

public async virtual Task ExecuteCommandAsync(string sqlCommand)

{

  await context.Database.ExecuteSqlCommandAsync(new RawSqlString(sqlCommand));

}

As you can see, the record exists:

When I save an unrelated data with SaveData, its ID is stored as binary data:

So maybe Entity Framework Core is somehow confused when trying to convert binary data to text? Still don't know why retrieve works normally then.