CODEWITHSUNDEEP
c#nhibernate
panjo
panjo

Reputation: 3515

mapping entity cannot be done cause it cannot find propety

I have Page entity with properties Keyword and Keywords.

Keyword property store one string like string Keyword = "my awesome page, page";

Keyword will store this information inside database.

Keywords on the other hand retrieve this keyword content and separating with commas.

so I have inside my model

public Page : Entity<int>
{
   public virtual string Keyword {get; set;}
   public virtual IList<string> Keywords 
   {
       get { return Keyword.Split(','); }
       set { Keyword = string.Join(",", value); }
   }
   public Page() { Keywords = new List<string>(); }
}

so I tried to map this entity with conformist mapping by code

public class PageMap : ClassMapping<Page>
{
    public PageMap()
    {
       Property(x => x.Keyword);
       Property(x => x.Keywords, m =>
            { 
                m.Access(Accessor.Field);                    
       });
    }
}

but I'm getting expcetion like

NHibernate.MappingException : Could not compile the mapping document: mapping_by_code ----> NHibernate.MappingException : Problem trying to set property type by reflection NHibernate.PropertyNotFoundException : Could not find property nor field 'Keywords' in class 'Model.Page'

Even I understand message that property cannot be found I do not understand why? and how to overcome this.

thanks

Upvotes: 2

Views: 2320

Answers (1)

Radim K&#246;hler
Radim K&#246;hler

Reputation: 123901

There are two issues. First, the Keywords property is "virtual", meaning that it is not persisted, it is calculated/built in runtime. To make it working you do not need to map and therefore to store it. Just remove the Keywords mapping...

The Second thing is the mapping. In case, that Keywords won't be virtual (runtime resolved based ont the Keyword property value), we have to map it as collection. Any collection (e.g. IList<string>) represents one-to-many relation, (in fluent called HasMany):

<bag name="Keywords" table="Keywords">
  <key column="PageId" />
  <element column="Keyword" />
</bag>

This will store all keywords in its own table (e.g. Keywords), referenced by PageId column and persisted in a column (e.g. nvrachar) called Keyword. The Fluent syntax would be like:

HasMany(x => x.Keywords)
    .Table("Keywords")
    .KeyColumn("PageId")
    .Element("Keyword");

But, as already said: if the Keywords is virutal, do not map it.

Upvotes: 1

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