Is there a way to get Swashbuckle to add OData parameters to Web API 2 IQueryable<T> endpoint?

Question

I have an ASP.Net Web API 2 endpoint that supports OData queries. It is as such:

[HttpGet, Route("")]
public IQueryable<Thing> Get()
{
    return _thingsRepository.Query();
}

The OData $filter parameter and such work great. I just wish they would show up in Swagger like they do for actual OData controllers.

I am using Swashbuckle.OData ... but I'm really not sure that it's buying me anything in this case.

Answer 1

It turns out it's pretty easy to add whatever parameters you want to Swagger using SwashBuckle using an IOperationFilter. You can add it in your Swagger Configuration using c.OperationFilter<ODataParametersSwaggerDefinition>();. I created one that adds some OData Parameters to all IQueryable endpoints in my API:

/// <summary>
///     Add the supported odata parameters for IQueryable endpoints.
/// </summary>
public class ODataParametersSwaggerDefinition : IOperationFilter
{
    private static readonly Type QueryableType = typeof(IQueryable);

    /// <summary>
    ///     Apply the filter to the operation.
    /// </summary>
    /// <param name="operation">The API operation to check.</param>
    /// <param name="schemaRegistry">The swagger schema registry.</param>
    /// <param name="apiDescription">The description of the api method.</param>
    public void Apply(Operation operation, SchemaRegistry schemaRegistry, ApiDescription apiDescription)
    {
        var responseType = apiDescription.ResponseType();

        if (responseType.GetInterfaces().Any(i => i == QueryableType))
        {
            operation.parameters.Add(new Parameter
            {
                name = "$filter",
                description = "Filter the results using OData syntax.",
                required = false,
                type = "string",
                @in = "query"
            });

            operation.parameters.Add(new Parameter
            {
                name = "$orderby",
                description = "Order the results using OData syntax.",
                required = false,
                type = "string",
                @in = "query"
            });

            operation.parameters.Add(new Parameter
            {
                name = "$skip",
                description = "The number of results to skip.",
                required = false,
                type = "integer",
                @in = "query"
            });

            operation.parameters.Add(new Parameter
            {
                name = "$top",
                description = "The number of results to return.",
                required = false,
                type = "integer",
                @in = "query"
            });

            operation.parameters.Add(new Parameter
            {
                name = "$count",
                description = "Return the total count.",
                required = false,
                type = "boolean",
                @in = "query"
            });
        }
    }
}