Ayende @ Rahien

Hi!
My name is Ayende Rahien
Founder of Hibernating Rhinos LTD and RavenDB.
You can reach me by phone or email:

ayende@ayende.com

+972 52-548-6969

, @ Q c

Posts: 5,949 | Comments: 44,547

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Searching for a lease in time & space


For some reason, there are a lot of real estate / rental people using RavenDB. I can tell you that I did not see that coming. However, that does bring us some interesting decisions.

In particular, at one client, we had the need to search for a lease. Searching for a lease can be done on one of many interesting properties. For example, the unit number, or internal code, or by the leaser name.

And here we got an interesting bug report.

Jane Smith leased an apartment from us at Dec 2012. At Feb 2013, she got married and changed her name to Jane Smith-Smyth. We need to allow searches on both names to find the appropriate lease.

Now, remember, you can’t go and change the lease document. That is a legal document that is frozen. Any change to that would invalidate it. (To be rather more accurate, you can modify the document, but there are certain fields that are frozen after the lease is signed.)

Luckily, this was really easy to do, using RavenDB’s referenced document feature:

   1: from lease in docs.Leases
   2: select new
   3: {
   4:    Leasers = lease.Leasers.Select(x=>x.Name)
   5:               .Union(lease.Leasers.Select(x=>LoadDocument(x.Id).Name))
   6:               .Distinct()
   7: }

And now we can support changes in the names, while maintaining the sanctity of the frozen fields.

Sadly, this is still not enough. And we actually need to keep track of all of the names that the leaser had during the leasing period.

Jane Smith-Smyth decided that it is a stupid name and changed her name to Jane Smite.

Now we need to support multiple names per leaser, while at the same time we have the current name for the lease. It looks like this:

   1: from lease in docs.Leases
   2: select new 
   3: {
   4:     Leasers = lease.Leasers.Select(x=>x.Name)
   5:     .Union(lease.Leasers.SelectMany(x=>LoadDocument(x.Id).Names))
   6:     .Distinct()  
   7: }

I highlighted the required changes Smile.


Comments

Grastveit

.Distinct() can be removed, right? .Union() already does it. Even nicer then.

Ayende Rahien

Grastveit, Correct, I assumed that this is like Concat

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