Fluent-NHibernate – Smooth NHibernate and calculation properties

public virtual DateTime? LastActionTimeStamp
{
 get {
 return Actions.Count == 0? null: Actions.OrderByDescending(
 a => a.TimeStamp) .ElementAt(0).TimeStamp;
 }
}

private int _postCount = 0;
public virtual int PostCount
{
 get< br /> {
 return _postCount;
 }
}

(SELECT count(p. ID) FROM BlogPost p WHERE p.BlogID = ID and p.IsDeleted = 0)

* property
* field
* field.camelcase
* field.camelcase-underscore
* field.pascalcase-m-underscore
* field.lowercase-underscore
* nosetter.camelcase
* nosetter.camelcase-underscore
* nosetter.pascalcase-m-underscore
* nosetter.lowercase-underscore

I am using Fluent NHibernate and automatically map the class.

I have a calculated attribute in a class< /p>

public virtual DateTime? Las tActionTimeStamp
{
 get {
 return Actions.Count == 0? null: Actions.OrderByDescending(
 a => a.TimeStamp).ElementAt(0).TimeStamp;< br /> }
}

This is not mapped with other properties, so I cannot use it in ICriteria restrictions. I added an empty setter (because I read somewhere to do Will include it in the mapping, it does), but now I receive an N​​Hibernate error:

could not execute query… Invalid column name ‘LastActionTimeStamp’.

So my question is: how do I tell Fluent NHibernate to tell NHibernate to ignore the database of this attribute, but still return the calculated value from the attribute get?

You can associate a formula with an attribute, and use the formula instead of c# code. For example,

Attribute:< /p>

private int _postCount = 0;
public virtual int PostCount
{
 get
 {
 return _postCount;< br /> }
}

Formula:

(SELECT count(p.ID) FROM BlogPost p WHERE p.BlogID = ID and p.IsDeleted = 0)

Then you can use PostCount in the expression as usual. Remember to set the access modifier on the attribute in FluentMapping. Not sure what Fluent supports, but the normal mapping I found The options are:

* property
* field
* field.camelcase
* field.camelcase-underscore
* field. pascalcase-m-underscore
* field.lowercase-underscore
* nosetter.camelcase
* nosetter.camelcase-underscore
* nosetter.pascalcase-m-underscore
* nosetter.lowercase-underscore

It may be best to check the NHibernate document of the official list Access Strategies in order to combine the access strategy with the naming strategy, for example: “field.lowercase underscore”