private Version latestVersion;
public virtual Version LatestVersion {
get{
if(lastestVersion == null)
{
lastestVersion = GetLatestVersion(this.AllVersions);
}
return latestVersion;
} }
When you change something in AllVersions you should call :
void InvalidateVersions()
{
lastestVersion= null;
}
to map it:
<many-to-one name="LatestVersion" access="nosetter.camelcase"/>
2010/2/23 Chris B <[email protected]>
> Fabio,
>
> I think you are saying I could implement it like this:
>
> public class Header
> {
> public virtual int HeaderId { get; set; }
> public virtual Version LatestVersion { get{ return
> GetLatestVersion(this.AllVersions); } }
> public virtual Version LatestApprovedVersion { get{ return
> GetLatestApprovedVersion(this.AllVersions); } }
> public virtual List<Version> AllVersions { get; set; }
> // other members
> }
>
> I had considered this kind of implementation, but the number of
> version entities can be large and all but two (the latest and latest
> approved) are very rarely used. I am hoping the AllVersions
> collection can be loaded only when viewing version history (rare), and
> not during normal workflow operations (common). I am assuming that
> accessing the AllVersions collection will load all versions, even if
> only one Version is being inquired about. So for example,
>
> Header h = ReadHeader();
> Version v = h.AllVersions[4]; // lazy loads all versions into the
> AllVersions collection, not just the one at index 4
>
> I am also not sure where the reference to Invoice.TotalAmmount came
> from. My entities do not have such a field.
>
> On Feb 23, 4:00 pm, Fabio Maulo <[email protected]> wrote:
> > ok... then is easy
> > You can map the two properties as access="readonly" and in its getter you
> > can read your collection to get LastXYZ.
> > The two properties will be saved as denormalized properties and you can
> use
> > it in any queries.
> >
> > If you want you can map it as access="nosetter.camelcase" and implements
> the
> > getter in order to read from collection when the private field is null
> > (Note: when you change the collection adding, removing or changing a
> member
> > you should "reset" the LastXYZ).
> >
> > In both case what will result "denormalized" is the DB but in your model
> > everything will be auto-protected...
> > in practice the same you are doing with Invoice.TotalAmmount
> >
> > 2010/2/23 Chris B <[email protected]>
> >
> >
> >
> > > There is also a list of all previous versions in the
> > > Header.AllVersions property. I had forgotten that I omitted it in my
> > > original post. The only use case where this is loaded is when a user
> > > requests to view the version history.
> >
> > > The LatestVersion and LatestApprovedVersion references are mainly for
> > > efficiency. Most use cases involve either displaying/mutating the
> > > data of the LatestVersion or reading the data of the
> > > LatestApprovedVersion. It would be great if we could selectively load
> > > those two versions (on demand) without having to load all versions.
> >
> > > Here is an updated entity definition:
> >
> > > public class Header
> > > {
> > > public virtual int HeaderId { get; set; }
> > > public virtual Version LatestVersion { get; set; }
> > > public virtual VersionLatestApprovedVersion { get; set; }
> > > public virtual List<Version> AllVersions { get; set; }
> > > // other members
> > > }
> >
> > > public class Version
> > > {
> > > public virtual int VersionId { get; set; }
> > > public virtual Header Header { get; set; }
> > > // other members
> > > }
> >
> > > Does that help to clarify?
> >
> > > On Feb 23, 11:15 am, Fabio Maulo <[email protected]> wrote:
> > > > you are showing only LatestVersion and LatestApprovedVersion
> > > > where are previous ?
> >
> > > > 2010/2/19 Chris B <[email protected]>
> >
> > > > > Hello,
> >
> > > > > I am trying to create a mapping file for entities which look like
> the
> > > > > following:
> >
> > > > > public class Header
> > > > > {
> > > > > public virtual int HeaderId { get; set; }
> > > > > public virtual Version LatestVersion { get; set; }
> > > > > public virtual VersionLatestApprovedVersion { get; set; }
> > > > > // other members
> > > > > }
> >
> > > > > public class Version
> > > > > {
> > > > > public virtual int VersionId { get; set; }
> > > > > public virtual Header Header { get; set; }
> > > > > // other members
> > > > > }
> >
> > > > > The database looks almost exactly like this, with the obvious
> > > > > difference being that instead of object references there are
> foreign
> > > > > keys for the latest/latest approved versions pointing to the
> VersionId
> > > > > field, and the same for the Header and HeaderId. The table for the
> > > > > header does allow both the latest and latest approved version ids
> to
> > > > > be null to allow the Header records to be inserted before the
> Versions
> > > > > are created. The insert proc for the Version table takes care of
> > > > > updating the Header.LatestVersionId to point at newly inserted
> version
> > > > > record.
> >
> > > > > I have thus far been unsuccessful in creating mapping files for
> this
> > > > > pattern, the sticking point being the LatestVersion and
> > > > > LatestApprovedVersion properties. I'm pretty new to NHibernate, so
> I
> > > > > apologize if this is answered in another thread.
> >
> > > > > Any help is much appreciated. Thanks in advance.
> >
> > > > > --
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> >
> > > <nhusers%[email protected]<nhusers%[email protected]>
> <nhusers%[email protected]<nhusers%[email protected]>
> >
> >
> > > > > .
> > > > > For more options, visit this group at
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> >
> > > > --
> > > > Fabio Maulo
> >
> > > --
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> >
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> >
> > --
> > Fabio Maulo
>
> --
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>
--
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