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ASP.NET Core–Open API–Possible parameter values

I’m currently building an ASP.NET Core API used to convert between document formats. You can upload a document, specify the from and to format and get a converted document back.

The list of supported conversions is dynamically determined based on a list of format providers loaded through a plugin architecture.

To help developers in getting to know the API, I created Open API documentation using Swagger. Unfortunately the generated Open API documentation wasn’t that useful out-of-the-box as you get no hint on the possible “from” and “to” values.

My first idea would be to change the string value to an enum but this would require a recompile every time a new document format is introduced(and make my plugin architecture obsolete). My second idea was to just update the documentation, but in fact this was even worse than my first idea.

Time to find a better solution: I created a custom ParameterFilter that dynamically generates a list of available values based on the loaded plugins.

Here is the ParameterFilter:

And here is the updated Swagger registration:

My Open API documentation now looks like this:

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