private static MethodCallExpression SetValue(ParameterExpression result, Type fromType, Column to, Expression value)
{
if (to.Type != fromType)
{
// type if not the same, can it be assigned?
if (Types.CanBeCast(fromType, to.Type))
{
value = Expression.Convert(value, to.Type);
}
else if (Types.IsNullable(fromType) && fromType.GetGenericArguments()[0] == to.Type)
{
value = Expression.Convert(value, to.Type);
}
else if (Types.IsNullable(fromType) && Types.CanBeCast(fromType.GetGenericArguments()[0], to.Type))
{
value = Expression.Convert(value, to.Type);
}
else
{
return(null);
}
}
if (to.Type == typeof(byte[]))
{
var setBytes = typeof(SqlDataRecord).GetMethod("SetBytes", new[] { typeof(int), typeof(long), typeof(byte[]), typeof(int), typeof(int) });
Contract.Assert(setBytes != null);
return(Expression.Call(result, setBytes, Expression.Constant(to.Ordinal), Expression.Constant(0L), value, Expression.Constant(0), Expression.PropertyOrField(value, "Length")));
}
var setMethod = typeof(SqlDataRecord).GetMethod(SetMethodName(to.Type), new[] { typeof(int), to.Type });
Contract.Assert(setMethod != null);
return(Expression.Call(result, setMethod, Expression.Constant(to.Ordinal), value));
}
static Expression ReadValue(ParameterExpression input, Mapping <Thing, Thing> map)
{
Expression value = Expression.PropertyOrField(input, map.From.Name);
var fromType = map.From.Type;
var toType = map.To.Type;
if (fromType == toType)
{
return(value);
}
if (Types.CanBeCast(fromType, toType)) // e.g. int to long
{
return(Expression.Convert(value, toType));
}
if (Types.IsNullable(fromType))
{
Expression fromValueOrDefault = Expression.Call(value, fromType.GetMethod("GetValueOrDefault", Type.EmptyTypes));
var fromArgType = Types.NullableOf(fromType);
if (fromArgType == toType) // e.g. int? to int
{
return(fromValueOrDefault);
}
var cast = Types.GetExplicitCastOperator(fromArgType, toType);
if (cast != null) // e.g. IntId<>? to int
{
return(Expression.Call(cast, fromValueOrDefault));
}
if (Types.IsNullable(toType))
{
// nullable<> to nullable<> conversion must handle null to null as a special case
var toArgType = toType.GetGenericArguments()[0];
if (Types.CanBeCast(fromArgType, toType)) // e.g. int? to long?
{
return(Expression.Condition(Expression.PropertyOrField(value, "HasValue"), Expression.Convert(fromValueOrDefault, toType), Expression.Default(toType)));
}
cast = Types.GetExplicitCastOperator(fromArgType, toArgType); // e.g. IntId<>? to int?
if (cast != null)
{
fromValueOrDefault = Expression.Call(cast, fromValueOrDefault);
}
return(Expression.Condition(Expression.PropertyOrField(value, "HasValue"), Expression.Convert(fromValueOrDefault, toType), Expression.Default(toType)));
}
if (Types.CanBeCast(fromArgType, toType)) // e.g. int? to long
{
return(Expression.Convert(fromValueOrDefault, toType));
}
}
if (Types.IsNullable(toType))
{
var toArgType = toType.GetGenericArguments()[0];
var cast2 = Types.GetExplicitCastOperator(fromType, toArgType); // e.g. IntId<> to int?
if (cast2 != null)
{
return(Expression.Convert(Expression.Call(cast2, value), toType));
}
}
var cast3 = Types.GetExplicitCastOperator(fromType, toType); // e.g. IntId<> to int
if (cast3 != null)
{
return(Expression.Call(cast3, value));
}
throw new InvalidOperationException("Should never get here has types compatibility has been checked");
}