Update existing documents with new (c# read-only) property

[Trygve Lorentzen]

What is the best approach for updating existing documents with the value of a get-only (read-only) property in the C# class? Basically all I need is to load all documents and SaveOrUpdate them for the new (calculated) property to be stored in the document. If using the patching API, would I need to implement the same logic in javascript that I do in C# to calculate the value?

[Michael Yarichuk]

If the logic for calculated property is not too complicated, I would go for implementing it in javascript and use it in patching requests. More efficient this way.

On Wed, Mar 25, 2015 at 3:11 PM, Trygve Lorentzen <try...@lorentzenconsult.com> wrote:

What is the best approach for updating existing documents with the value of a get-only (read-only) property in the C# class? Basically all I need is to load all documents and SaveOrUpdate them for the new (calculated) property to be stored in the document. If using the patching API, would I need to implement the same logic in javascript that I do in C# to calculate the value?

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[Daniel Lidström]

It depends on the amount of documents. One simple approach for a relatively small number of documents is to simply migrate them all:

var query = DocumentSession.Query<YourModel, YourModelIndex>();

var current = 0;

while (true)

{

    var results = query.Skip(current)

                       .Take(128)

                       .ToArray();

    if (results.Length == 0) break;

    foreach (var result in results)

    {

        // do anything with result, or just wait for SaveChanges...

    }

    current += results.Length;

}

If you have a large amount of documents you may have to create new document sessions for every x items.

See https://github.com/ayende/RaccoonBlog/blob/master/RaccoonBlog.Migrations/Program.cs

Don't make this any more complex (i.e. JavaScript) than it needs to be!

[Grisha Kotler]

If you want to iterate over the entire set of a query result, you should use the Streaming API.

http://ravendb.net/docs/article-page/2.5/csharp/client-api/advanced/unbounded-results

And saving the documents using bulk insert.

Hibernating Rhinos Ltd  

Grisha Kotler l RavenDB Core Team Developer l Mobile: +972-54-586-8647

Office: +972-4-622-7811 l Fax: +972-153-4-622-7811

RavenDB paving the way to "Data Made Simple" http://ravendb.net/

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[Chris Marisic]

In situations like this I would always choose to use the patch api first. I would create the property in C# and then use the patch api to update existing documents.

If the property was hard to reproduce in the patch api I would load and save all the documents. For this scenario I preferred using Advanced.LoadStartingWith, at this point it's probably easier to use the document streaming