NHibernate - is there any point in setting length attribute for properties/columns?

Question

typically definition of property/column looks like this:

<property name="DocumentSummary" column="DocumentSummary" length="100" type="String">
   <column name="DocumentSummary" />
</property>

I was assuming that NHibernate will validate data using length attribute before inserting/updating a row. Unfortunately it seems to be invalid assumption. So question is if NHibernate is using length attribute for anything? Does it make sense to set it for each property?

score 4 · Accepted Answer · answered Mar 10 '09 at 20:27

4

It using it to create database definition sql. Look at SchemaExport class.

answered Mar 10 '09 at 20:27

Alex Reitbort

13,504
1
40
61

score 1 · Answer 2 · edited May 23 '17 at 10:33

1

Also you might be able to programmically pull the lengths from the mappings, see this question. Note that that is for Java Hibernate, but I believe you might be able to translate that to NHibernate.

edited May 23 '17 at 10:33

Community

1
1

answered Mar 10 '09 at 20:30

James McMahon

48,506
64
207
283

score 0 · Answer 3 · answered Jun 09 '17 at 04:08

Yes, setting the Length property makes a different where you have string columns with a length that exceeds the default maximum length.

We have a column of type NVARCHAR(MAX). If we didn't set the length property, NHibernate would fail to set the string value if the value had a length greater than 4096 characters.

(This example uses Mapping-By-Code, because we're in 2017 :-)

classMapper.Property(
                        tickerFeed => tickerFeed.StaticTickerText,
                        propertyMapper =>
                        {
                             propertyMapper.Column("StaticTickerText");
                             propertyMapper.Length(int.MaxValue);
                        }
                    );

However, we found we could achieve the same result using IPropertyMapper.Type to stipulate that it was a large string.

classMapper.Property(
                        tickerFeed => tickerFeed.StaticTickerText,
                        propertyMapper =>
                        {
                             propertyMapper.Column("StaticTickerText");
                             propertyMapper.Type(NHibernateUtil.StringClob);
                        }
                    );

We ended up going with the propertyMapper.Type option, as it is more explicit.

NHibernate - is there any point in setting length attribute for properties/columns?

3 Answers3