Computed columns migration error

[heggi]

In EFCore 3.1 I did:

migrationBuilder.CreateTable(
      name: "Worker",
      columns: t => new {
          LastName = t.Column<string>(type: "varchar(64)"),
          FirstName = t.Column<string>(type: "varchar(64)"),
          MiddleName = t.Column<string>(type: "varchar(64)"),
          FullName = t.Column<string>(type: "varchar(128)",
              computedColumnSql: @"trim(""LastName"" || ' ' || ""FirstName"" || ' ' || ""MiddleName"")"),
      }
  )

In EFCore 5.0 this code got error System.NotSupportedException: Generated columns currently must be stored, specify IsStoredComputedColumn in your context's OnModelCreating

I added to DbContext

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Worker>()
        .Property(m => m.FullName)
        .HasComputedColumnSql(@"trim(""LastName"" || ' ' || ""FirstName"" || ' ' || ""MiddleName"")", stored: true);
}

But got the same error

If I remove computedColumnSql: "..." from migration code, I get general column.

My Entity:

public class Worker
{
    public string LastName { get; set; }
    public string FirstName { get; set; }
    public string MiddleName { get; set; }

    [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
    public string FullName { get; set; }
}

Where is the error?

[heggi]

I found the solution.
EFCore 5.0 required define stored param (true or false)

migrationBuilder.CreateTable(
      name: "Worker",
      columns: t => new {
          LastName = t.Column<string>(type: "varchar(64)"),
          FirstName = t.Column<string>(type: "varchar(64)"),
          MiddleName = t.Column<string>(type: "varchar(64)"),
          FullName = t.Column<string>(type: "varchar(128)",
              computedColumnSql: @"trim(""LastName"" || ' ' || ""FirstName"" || ' ' || ""MiddleName"")", stored: true),
      }
  )

Error's message doesn't make clear how to fix this problem.

[roji]

@heggi this is an unfortunate consequence of the changes made to properly support stored vs. non-stored columns in EF Core - see the breaking change note on this. I'm adding another sentence there about the need to fix up existing migration code (npgsql/doc@f91b745).

[fe-c]

What about "42P17: Generator Expression Is Not Constant ", in case of expressions that depends on the date?

[roji]

@fe-c that is a PostgreSQL limitation of what expression can be used inside computed columns - see these docs for the precise restrictions (similar restrictions typically exist for other databases as well). In any case, this has nothing really to do with Npgsql or the EF Core provider.

[fe-c]

Yes, indeed, I misunderstood the description and decided that virtual computable values are supported by Postgre. THX.