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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> > > --
> > > Fabio Maulo
>
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> Fabio Maulo
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