Web Api How to add a Header parameter for all API in Swagger

Question

I searched for possible ways to add a request header parameter that would be added automatically to every method in my web-api but I couldn't find a clear one.

While searching I found that the method OperationFilter() has something to do with it.

Answer 1

Yes you can do it via inheriting from IOperationFilter

You can find the answer on GitHub here: AddRequiredHeaderParameter

using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc.ApiExplorer;
using Swashbuckle.AspNetCore.Swagger;
using Swashbuckle.AspNetCore.SwaggerGen;

public class AddRequiredHeaderParameter : IOperationFilter
{
    public void Apply(Operation operation, OperationFilterContext context)
    {
        if (operation.Parameters == null)
            operation.Parameters = new List<IParameter>();

        operation.Parameters.Add(new NonBodyParameter
            {
                Name = "X-User-Token",
                In = "header",
                Type = "string",
                Required = false
            });
    }
}

Then you go to your SwaggerConfig.cs file and add the following in the AddSwaggerGen section:

c.OperationFilter<AddRequiredHeaderParameter>();

Rebuild, and enjoy.