Computed field in Servicestack ormlite error

Question

I couldn't make it work, I added the data annotation for a computed field using ServiceStack ormlite Sql server:

[Compute, Ignore]
public string FullName { get; set; }

The problem is that my LoadSelect<Employee>() method doesn't load the colunm FullName from a computed field. Why?

if I remove the [Ignore] it loads, but then when I use the.create() method to create a new record, it returns an error, probably because it tries to add a value for the FullName field.

Table

CREATE TABLE [dbo].[Employee](
    [EmployeeId] [int] IDENTITY(1,1) NOT NULL,
    [FullName]  AS (concat(ltrim(rtrim([FirstName])),' ',ltrim(rtrim([LastName])))) PERSISTED NOT NULL,
    [FirstName] [nvarchar](55) NOT NULL,
    [LastName] [nvarchar](55) NULL,
    [Username] [nvarchar](55) NOT NULL,
    [Password] [nvarchar](55) NULL
 CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED 
(
    [EmployeeId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 80) ON [PRIMARY]
) ON [PRIMARY]

Employee class:

[Schema("dbo")]
[Alias("Employee")]
public class Employee : IHasId<int>
{
    [PrimaryKey]
    [Alias("EmployeeId")]
    [AutoIncrement]
    [Index(Unique = true)]
    public int Id { get; set;}

    [Required]
    public string FirstName { get; set; }
    public string LastName { get; set; }

    [Required]
    [Index(true)]
    public string Username { get; set; }

    public string Password { get; set; }

    [Compute, Ignore]
    public string FullName { get; set; }
}

Get method:

    public virtual async Task<IEnumerable<T>> Get<T>() where T : IHasId<int>
    {
        using (var dbCon = DbConnectionFactory.OpenDbConnection())
        {
            return await dbCon.LoadSelectAsync<T>(x => x);
        }
    }

Create method:

    public virtual async Task<T> Create<T>(T obj) where T: IHasId<int>
    {
        using (var dbCon = DbConnectionFactory.OpenDbConnection())
        {
            // if there is an id then INSERTS otherwise UPDATES
            var id = obj.GetId().SafeToLong();

            if (id > 0)
                dbCon.Update(obj);
            else
                id = dbCon.Insert(obj, true);   

            // returns the object inserted or updated
            return await dbCon.LoadSingleByIdAsync<T>(id);
        }
    }

Answer 1

The [Ignore] attribute tells OrmLite you want it to ignore the property completely which is not what you want, you need to just use the [Compute] attribute to handle computed columns which I've just added a test for in this commit which is working as expected in the latest version of OrmLite, e.g:

db.DropTable<Employee>();
db.ExecuteSql(@"
CREATE TABLE [dbo].[Employee](
[EmployeeId] [int] IDENTITY(1,1) NOT NULL,
[FullName]  AS (concat(ltrim(rtrim([FirstName])),' ',ltrim(rtrim([LastName])))) PERSISTED NOT NULL,
[FirstName] [nvarchar](55) NOT NULL,
[LastName] [nvarchar](55) NULL,
[Username] [nvarchar](55) NOT NULL,
[Password] [nvarchar](55) NULL
CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED ([EmployeeId] ASC)");

var item = new Employee
{
    FirstName = "FirstName",
    LastName = "LastName",
    Username = "Username",
    Password = "Password",
    FullName = "Should be ignored",
};

var id = db.Insert(item, selectIdentity: true);

var row = db.LoadSingleById<ComputeTest>(id);

Assert.That(row.FirstName, Is.EqualTo("FirstName"));
Assert.That(row.FullName, Is.EqualTo("FirstName LastName"));

row.LastName = "Updated LastName";
db.Update(row);

row = db.LoadSingleById<ComputeTest>(id);

Assert.That(row.FirstName, Is.EqualTo("FirstName"));
Assert.That(row.FullName, Is.EqualTo("FirstName Updated LastName"));

Which also works using the async API's in your Create() helper method, e.g:

var row = await Create(item);

Assert.That(row.FirstName, Is.EqualTo("FirstName"));
Assert.That(row.FullName, Is.EqualTo("FirstName LastName"));

row.LastName = "Updated LastName";
row = await Create(row);

Assert.That(row.FirstName, Is.EqualTo("FirstName"));
Assert.That(row.FullName, Is.EqualTo("FirstName Updated LastName"));

I'm assuming you're using an older version of OrmLite, if you upgrade to the latest version it should work.