Mapping TimeSpan in SQLite and Dapper
I'm attempting to use Dapper to interface to an existing database format that has a table with a duration encoded as ticks in a BIGINT column. How do I tell Dapper to map my POCO's TimeSpan -typed property to ticks when inserting into and reading from the database?
I've tried to set the type map for TimeSpan to DbType.Int64 :
SqlMapper.AddTypeMap(typeof(TimeSpan), DbType.Int64);
And I've also created an ITypeHandler , but the SetValue method is never called:
public class TimeSpanToTicksHandler : SqlMapper.TypeHandler<TimeSpan>
{
public override TimeSpan Parse(object value)
{
return new TimeSpan((long)value);
}
public override void SetValue(IDbDataParameter parameter, TimeSpan value)
{
parameter.Value = value.Ticks;
}
}
Here's my POCO:
public class Task
{
public TimeSpan Duration { get; set; }
// etc.
}
When executing a simple insert statement like this:
string sql = "INSERT INTO Tasks (Duration) values (@Duration);";
And passing the POCO as the object to insert:
Task task = new Task { Duration = TimeSpan.FromSeconds(20) };
connection.Execute(sql, task);
I get this exception:
System.InvalidCastException : Unable to cast object of type 'System.TimeSpan' to type 'System.IConvertible'.
at System.Convert.ToInt64(Object value, IFormatProvider provider)
at System.Data.SQLite.SQLiteStatement.BindParameter(Int32 index, SQLiteParameter param)
at System.Data.SQLite.SQLiteStatement.BindParameters()
at System.Data.SQLite.SQLiteCommand.BuildNextCommand()
at System.Data.SQLite.SQLiteCommand.GetStatement(Int32 index)
at System.Data.SQLite.SQLiteDataReader.NextResult()
at System.Data.SQLite.SQLiteDataReader..ctor(SQLiteCommand cmd, CommandBehavior behave)
at System.Data.SQLite.SQLiteCommand.ExecuteReader(CommandBehavior behavior)
at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery(CommandBehavior behavior)
at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery()
at Dapper.SqlMapper.ExecuteCommand(IDbConnection cnn, ref CommandDefinition command, Action`2 paramReader) in SqlMapper.cs: line 3310
at Dapper.SqlMapper.ExecuteImpl(IDbConnection cnn, ref CommandDefinition command) in SqlMapper.cs: line 1310
at Dapper.SqlMapper.Execute(IDbConnection cnn, String sql, Object param, IDbTransaction transaction, Nullable`1 commandTimeout, Nullable`1 commandType) in SqlMapper.cs: line 1185
If I leave the TimeSpan type mapping as-is (it defaults to DbType.Time ), it writes the string version of the TimeSpan , ie `00:00:20.000", which isn't helpful as it does not match the format of the other data in the column.
你可以做下面的事情吗？
public class Task
{
public TimeSpan Duration { get; set; }
public long Ticks
{
get { return Duration.Ticks; }
set { Duration = new TimeSpan(value); }
}
// etc.
}
string sql = "INSERT INTO Tasks (Duration) values (@Ticks);";
Solutions for LinqToDB:
MappingSchema.SetDataType(typeof(TimeSpan), DataType.NText);
Or:
MappingSchema.SetDataType(typeof(TimeSpan), DataType.Int64);
Example:
public class Program
{
private const string ConnectionString = "Data Source=:memory:;Version=3;New=True;";
public static void Main()
{
var dataProvider = new SQLiteDataProvider();
var connection = dataProvider.CreateConnection(ConnectionString);
connection.Open();
var dataConnection = new DataConnection(dataProvider, connection);
dataConnection.MappingSchema.SetDataType(typeof(TimeSpan), DataType.Int64);
dataConnection.CreateTable<Category>();
dataConnection.GetTable<Category>()
.DataContextInfo
.DataContext
.Insert(new Category
{
Id = 2,
Time = new TimeSpan(10, 0, 0)
});
foreach (var category in dataConnection.GetTable<Category>())
{
Console.WriteLine($@"Id: {category.Id}, Time: {category.Time}");
}
}
private class Category
{
public int Id { get; set; }
public TimeSpan Time { get; set; }
}
}