How to disable AdditionalProperties being generated in Swagger

[nitinpasula]

Hi, We are using RestEasy to build our rest services and swagger annotations for documentation. We are upgrading from a very old version of swagger UI 2.x to 4.10.3. Seeing below in few object responses, which were not showing before, Is there any way to disable them being generated.

{
"additionalProp1": {},
"additionalProp2": {},
"additionalProp3": {}
}

[Lukas-Pacl]

I had the same problem with using the .NET 6 Swashbuckle package and solved it by creating a custom schema filter that disabled additional properties. From research, I found out that since some version of swagger AdditionalProperties is set globally to True instead of False for some reason.

Here is my schema filter implementation

public class AdditionalPropertiesSchemaFilter : ISchemaFilter
{
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        schema.AdditionalPropertiesAllowed = false;
    }
}

and here how to use it with swagger in .NET 6

services.AddSwaggerGen(c =>
{
    ...
    c.SchemaFilter<AdditionalPropertiesSchemaFilter>();
});

I hope this will at least help point you in the right direction

[kjkrum]

Note that OpenApiSchema has two related properties: AdditionalPropertiesAllowed and AdditionalProperties. If you just don't want to see "additionalProperty1" etc. in the Swagger UI, leave AdditionalPropertiesAllowed true and set AdditionalProperties to null. I think AdditionalPropertiesAllowed allows for future changes, while AdditionalProperties tells the consumer to expect additional properties, for example with types like ProblemDetails.