Type Converters

[Mensur]

I am trying to get a type converter to work but the app is complaining that the converter cannot be found. I created a FluentAPI project and added a converter there by following this FluentAPI blog post and this type converters Blog post. I basically have two classes: Book and Identifier and if I don't have a type converter everything seems to be fine. I am trying to convert date/time to a text representation which is how the date/time is stored in SQLite database:

public class SqliteDateToDateTime : AdoTypeConverter
{
    private bool nullable;

    public override AdoTypeConverter Initialize(IDataColumn user, Type clr,
                                                     IAdoTypeConverterRegistry registry, bool secondaryTable)
    {
        //first we need to ensure that the clr type can be handled by this converter
        if (clr == typeof (DateTime) && user.ResolvedSqlType == "varchar")
        {
            //then we need to set a flag to determine if the type is nullable
            nullable = typeof (DateTime?) == clr;

            //finally return base.Initialize, which ultimatly returns "this"
            return base.Initialize(user, clr, registry, secondaryTable);
        }

        //if the converter can not work with the specified clr type we return null
        return null;
    }

    public override object Read(ref DataHolder holder)
    {
        //check if the value is dbnull
        bool isNull = holder.Reader.IsDBNull(holder.Position);

        //set wheather or not there is a value
        holder.NoValue = isNull;

        //if the value is null, then we need to return default values
        if (isNull)
        {
            //if the type is nullable, and the value is null, we simply return null
            if (nullable)
                holder.ObjectValue = null;
                //if the value is null, and we need to box it, we set the objectvalue to 0
            else if (holder.Box)
                holder.ObjectValue = 0;
            else
                //other wise the value is null, so we simply return the default int value
                holder.Int32Value = 0;
        }
        else
        {
            //the value is not null, so here we want to pull the value out, and convert it to a string
            DateTime dt;
            string s = holder.Reader.GetValue(holder.Position).ToString();
            int index = s.IndexOf("+");
            if (index >= 0)
            {
                dt = DateTime.Parse(s.Substring(0, s.IndexOf("+")));
            }
            else
            {
                dt = DateTime.Parse(s);
            }

            //if the value is nullabel, or needs to be boxed, we set the ObjectValue Property of the DataHolder
            if (nullable || holder.Box)
                holder.ObjectValue = dt;
            else
                //otherwise we can set the Int32Value property to the parseed int value
                holder.DateTimeValue = dt;
        }

        //now we return our value
        return holder.ObjectValue; // (holder.Box || nullable) ? holder.ObjectValue : null;
    }

    public override void Write(ref DataHolder holder)
    {
        //set the db type
        holder.Parameter.DbType = System.Data.DbType.String;

        //if there is no value we could specify what to set the db field to
        if (holder.NoValue)
        {
            //in this case we just want to set it to null
            holder.Parameter.Value = null;
        }
        else
        {
            //When there is a value we simply need to take our CLR int, and convert it to a string
            //and then set the parameter info
            string s = holder.DateTimeValue.ToString("yyyy-MM-dd HH:mm:ss+00:00");
            holder.Parameter.Size = s.Length;
            holder.Parameter.Value = s;
        }
    }

    public override bool CreateLiteralSql(ref DataHolder holder)
    {
        //If there is no value, then we just want to query against null.
        if (holder.NoValue)
        {
            holder.StringValue = "NULL";

            //returning false indicates that no quotes are required. We want NULL instead of 'NULL'
            return false;
        }
        else
        {
            //convert the int value into a string, since that is what we are storing it as in the db
            holder.StringValue = holder.DateTimeValue.ToString("yyyy-MM-dd HH:mm:ss+00:00");

            // return true indicates that quotes are needed around the value
            return true;
        }
    }

    public override Type DefaultType
    {
        get { return typeof (DateTime); }
    }
}

    
Again, the class is in the FluentAPI project and here is the PrepareMapping method:

protected override IList<MappingConfiguration> PrepareMapping()
{
    List<MappingConfiguration> configurations = new List<MappingConfiguration>();

    MappingConfiguration<Book> bookConfiguration = new MappingConfiguration<Book>();
    bookConfiguration.MapType(p => new
    {
        id = p.Id,
        title = p.Title
    }).ToTable("books");
    bookConfiguration.HasProperty(x => x.PublishedDate)
        .ToColumn("pubdate")
        .HasColumnType("text")
        .WithConverter<SqliteDateToDateTime>();
    bookConfiguration.HasProperty(p => p.Id).IsIdentity();

    MappingConfiguration<Identifier> identifierConfiguration = new MappingConfiguration<Identifier>();
    identifierConfiguration.MapType(p => new
    {
        id = p.Id,
        book = p.BookId,
        type = p.Type,
        val = p.Value
    }).ToTable("identifiers");
    identifierConfiguration.HasProperty(p => p.Id).IsIdentity();

    identifierConfiguration.HasAssociation(p => p.Book).WithOpposite(c => c.Identifiers).HasConstraint((p, c) => p.BookId == c.Id);

    configurations.Add(bookConfiguration);
    configurations.Add(identifierConfiguration);
    return configurations;
}

The error I am getting is this: Could not load type 'Data.SqliteDateToDateTime' from assembly 'Telerik.OpenAccess.Runtime, Version=2011.2.713.3, Culture=neutral, PublicKeyToken=7ce17eeaf1d59342'.":"Data.SqliteDateToDateTime"} System.Exception {System.TypeLoadException}.

Any help is appreciated.

[Mensur]

There must be someone who knows the answer to this?

[Ady]

Hello Mensur,

 I was able to reproduce the exception and we will fix this error. You can use the other overload of 'WithConverter' that use a string. Please change the code to the following:
bookConfiguration.HasProperty(x => x.PublishedDate)
                .ToColumn("pubdate")
                .HasColumnType("text")
                .WithConverter(typeof(SqliteDateToDateTime).AssemblyQualifiedName);

Hope this helps.

Do get back in case you need further assistance.

Greetings,
Ady
the Telerik team