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Comment by nightpool | Hacker News Reader

I'm not sure how you're blaming JSONSchema for "Half the fields in the type will be required … and the schema will say they're optional". But JSONSchema has plenty of ways to define sum types: http://json-schema.org/understanding-json-schema/reference/c...

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Am I right to call out most of this problem is caused by incessantly reusing types (because defining an additional type for i.e. CREATE vs PUT actions is soooo hard.

If you've already gone to the length of defining your DTO with 20+ typed fields including comments/annotations etc., why should you need to duplicate it between CREATE and PUT types? PATCH is probably the trickiest one to do cleanly - while I've used the model of "re-use the CREATE type, but all fields are now optional" in the past, I wouldn't actually recommend it, and probably promote proper JSONPatch format instead, the only real disadvantage being that it's a harder to manually construct the request body, which isn't something you should be too concerned about end-users having to spend time doing.

> gone to the length

Right there. Because typing 20 lines of source code should not be an argument for weakening your model layer. Re-use would be great if types were identical between actions, but in the real-world they're not and they accrue subtle differences over time.

Hmm. Thank you for that, I seem to be mistaken there. I wonder if that was added after I acquired my knowledge of JSONSchema? Or if it was some weird thing w/ Swagger where it wasn't supported there.

Swagger (OpenAPI 2) and OpenAPI 3 never supported JSON Schema. They support a subset of the draft 4 with custom additions. OpenAPI 3.1 added support for additional schemas where you can use whichever draft you want.

Might just be confusion with swagger / openapi, which is a complete mess of procedural constraints reminiscent of XML Schemas.

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