MsSql Dialect, mapping an nvarchar(max) using string(10000) causes string truncation

Matthias, have a look at NH-2484. If this is the issue you are experiencing, it will be fixed in the 3.1 release.

Alessandro, I am experiencing the same problem in 3.0.0.GA running on MSSQL 2008 with a MSSQL 2008 Dialect. The field in question is varchar(max) but the String is truncated after 4000 chars.

The same worked in NHibernate 2.1 without any problems or workaround.

Fabio Maulo's workaround does seems to work but I was wondering if is there is a chance for this to be permanently fixed in 3.1.0.

Thanks for your considerations,

Matt

Ok workaround found.
"StringClob" by default will generate a nvarcharmax and the value will be truncated at (int.MaxValue / 2).

The workaround fixes even the breaking change of type="string" length=10000

The 'workaround' is simple and easy, just modify the SqlClinetDriver (or write your custom one) changing the SetVariableLengthParameterSize() function to:

private static void SetVariableLengthParameterSize(IDbDataParameter dbParam, SqlType sqlType)
{
SetDefaultParameterSize(dbParam, sqlType);

// Override the defaults using data from SqlType.
if ((sqlType.LengthDefined) && !(sqlType is StringClobSqlType) && !(sqlType is BinaryBlobSqlType))
{
// we have to take into account a possible varchar or nvarchar (max), so assign the length
// to the string type and to the binary type only if it doesn't exceed the maximum allowed value
// otherwise use the MaxBinaryBlobSize or MaxStringClobSize
if (((sqlType.DbType == DbType.AnsiString) || (sqlType.DbType == DbType.AnsiStringFixedLength))
&& (sqlType.Length > MaxAnsiStringSize))
dbParam.Size = MaxBinaryBlobSize; // I'm not totally sure of this
else if (((sqlType.DbType == DbType.String) || (sqlType.DbType == DbType.StringFixedLength))
&& (sqlType.Length > MaxStringSize))
dbParam.Size = MaxStringClobSize;
else
dbParam.Size = sqlType.Length;
}

if (sqlType.PrecisionDefined)
{
dbParam.Precision = sqlType.Precision;
dbParam.Scale = sqlType.Scale;
}
}

I'm actually using this modified SqlClinetDriver without any issues...I've also tested it against the whole NHibernate Test Suite and all tests passed.
I'll write a blog post about this in the close future too.

To manage it as we properly, we should add a reference to Microsoft.SqlServer.Management (for example to use SqlDataType.NVarCharMax).
We can't.

We have to found a workaround.