Selecting the right information in the right format

Hey,

I'm doing many coaching projects right now, and there's one question that repeatedly pops up:

"What kind of projection should we best use for our queries?"

The answer to that question is simple:

If you want to change the information you select, use an entity projection. In all other cases, an unmanaged DTO projection provides better performance.

(I explain all of that in more detail in this article.)

The next question is then usually:

"Do we really need to create a new DTO projection for every use case?"

No, you don't need to use a use case-specific projection.

If multiple use cases require the exact same information, you can define 1 projection and reuse it. In most cases, that also means you can reuse the query statement.

But please don't create a DTO that matches your entity class. DTO projections provide better performance because they avoid entities' management overhead and only include the information you need. And that means they almost always can be much smaller than your entity classes.

Speak soon,

Thorben

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