CODEWITHSUNDEEP
c#databaseravendb
Zane Kaminski
Zane Kaminski

Reputation: 539

RavenDB polymorphic Index

I'm working with RavenDB, and I'm trying to do something. I have a base type, Principal, from which two classes are derived: User and ApplicationInstance. In my application, instances of User and ApplicationInstance must be created and stored frequently. The thing is, though, that I need to also be able to query all of the Principal objects stored in the database at once, determine whether a given Principal is a User or an ApplicationInstance, and then query for the entire User or ApplicationInstance object.

How can I do this?

Upvotes: 1

Views: 417

Answers (2)

Cristian Lupascu
Cristian Lupascu

Reputation: 40596

You can define a Multi Map Index that uses as source both the User and ApplicationInstance collections.

If you define your index using C# code (by implementing AbstractMultiMapIndexCreationTask<>), you'll have to call AddMap twice to achieve that (as illustrated in the blog post link above)

If you define the index using Raven Studio, simply click the Add Map button and you'll get a new text area which allows you to define an additional Map.

Note, however, that the output structure of both maps must have the same properties (pretty much as you would do with UNION in SQL).

Upvotes: 2

Judah Gabriel Himango
Judah Gabriel Himango

Reputation: 60061

What are you trying to do? If the end result is to query all Principals, then load the entire User or AppInstance, why not just go straight for querying all Users or all AppInstances?

Raven won't store base classes; it will only store the most derived type (User or AppInstance, in your case). So you'll have a collection of Users and a collection of AppInstances.

If you really need to query both at once, you can use Multi Map indexes. You can also change the entity name and store both in a single Principal collection.

But it's difficult to recommend a solution without knowing what you're trying to do. Explain what you're trying to do and we'll tell you the proper way to get there.

Upvotes: 1

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