The length of the string value exceeds the length configured in the mapping/parameter

Question

I am trying to insert some very long text into a string prop - it worked perfectly fine with LinqToSql, now I have switched over to NHibernate and want to save the same enti

Answer 1

Default maximum string length in NHibernate is 4000 characters.

Answer 2

This is a well known issue with NHibernate handling nvarchar(max), see :

http://geekswithblogs.net/lszk/archive/2011/07/11/nhibernatemapping-a-string-field-as-nvarcharmax-in-sql-server-using.aspx

For some years now, I have been file mapping nvarchar(max) columns to StringClob without encountering any problem :

<property name="myProp" column="MY_PROP" not-null="true" type="StringClob" access="property"></property>   

This link (from the comments) describes the fluent mapping required to fix this issue:

https://www.tritac.com/nl/blog/fluent-nhibernate-nvarchar-max-fields-truncated-to-4000-characters/

Map(x => x.Description).CustomType("StringClob").CustomSqlType("nvarchar(max)");

Answer 3

If you use nHibernate Mapping By Code (Not Fluent) I found here the solution:

https://groups.google.com/forum/#!topic/nhusers/uDAcP4BqFUU

Property(x => x.Description, c =>
   {
      c.Column("Product");
      c.Type(NHibernateUtil.StringClob);
   }
);

Answer 4

It's quite an old question and it seems there is a more straightforward solution now. I had the same issue and setting the length of the column to Int32.MaxValue in the mapping solved the problem :

Map(_ => _.Body).Length(Int32.MaxValue);

Answer 5

I hit a similar problem but using a CustomType (derived from IUserType). It turns out to be easier to fix than without a custom type. All you need to do is define SqlTypes to explicitly return the longer string length type you want.

public SqlType[] SqlTypes
{
    get
    {
        // Explicitly specify the string max length 
        return new SqlType[] { SqlTypeFactory.GetString(Int32.MaxValue / 2) };
    }
}

This solved the problem for us quite nicely.