Feature/input dtos

[jhoogstraat]

Provide a way to define the layout of request bodies and how the data is processed.

Description

Adds two Modifiers (SaveDTOModifier and UpdateDTOModifier) which require the programmer to define a struct conforming to either SaveDTOor UpdateDTO. These types are then decoded from the request body and used to save or update a model to the database.

Ideas

• Use Validations if present
• use OperationType .patch for updating, because of its 'partial updating' nature.

Related Issue

Fixes 50% of #3

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• SwiftLint throws no warnings or errors.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[jhoogstraat]

I’d like to emphasize that this solution does not allow the DTOs to grab information from other parts of the request than the request body (e.g. path components, query string or headers) in a very type safe manner. It is recommended to require requests to provide all information necessary to create the database item in the request body. That being said the DTOs still have access to the Request object, so no hard limitations there.

[bmikaili]

Looks nice overall! Just some questions for my understanding left as comments.

[jhoogstraat]

Before we merge, i think it should be discussed if this solution provides enough flexibility and performance (uses Mirror multiple times currently). I am currently working on supporting Enums and Parent/Sibling relations.

[bmikaili]

I think it's fine, performance isn't that big a priority, and it's flexible enough for what it needs to do.

[bmikaili]

@jhoogstraat Can you merge develop into this, then I would approve and merge the PR. You can use your CreateEndpoint, the implementations in develop only require that the protocol exists.

[jhoogstraat]

Changes are currently untested. Feedback welcome.

[PSchmiedmayer]

We will archive Corvus in favor of Apodini as a worthy successor.