skaempfer / example-required-nonnullable-webapi

Example project for trying out ways to harmonize 'required' validations with value-type and non-nullable model properties.

Force a required predicate on model properties with default values

Problem statement

Making a model property 'required' when it has a default value (value types) can be tricky because a model object's property will always have a value no matter if the data from the request to be bound to the model object contains a value for said property or not.

Solution shown here

The solution shown here makes use of the Newtonsoft.Json serializer's ability to mark an expected property as required before it is even bound to the C# object model. With this approach you can check for the availability of non-null data types during model binding.

How to start

• Execute dotnet run inside the project directory
• Execute Invoke-WebRequest -Uri http://localhost:5137/weatherforecast -Method Post -ContentType 'application/json' -Body '{}'
• You will receive a validation error on a value-type model property
• Execute Invoke-WebRequest -Uri http://localhost:5137/weatherforecast -Method Post -ContentType 'application/json' -Body '{"temperatureC": 25}'
• You will receive a 204 NoContent result since validation has passed