5.0.1 - XML documentation parser not very forgiving with param comment for missing parameter

[latenightcoder]

Hi again,

Turns out if the XML documentation has a param element specified but there are no parameters defined in the action, it blows up.

Example :-

        /// <summary>
        /// Gets basic profile data of logged-in user
        /// </summary>
        /// <param></param>
        /// <returns></returns>
        [HttpGet]
        public async Task<ApiResponse<VM.UserInfo>> Info()

Exception :-

Value cannot be null. Parameter name: source ---> System.ArgumentNullException: Value cannot be null. Parameter name: source

at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source, Func`2 predicate)
at Swashbuckle.Swagger.Filters.ApplyXmlActionComments.ApplyParamComments(Operation operation, XPathNavigator methodNode) in c:\Users\Joel\Documents\GitHub\Swashbuckle\Swashbuckle.Core\Swagger\Filters\ApplyXmlActionComments.cs:line 70
at Swashbuckle.Swagger.Filters.ApplyXmlActionComments.Apply(Operation operation, SchemaRegistry schemaRegistry, ApiDescription apiDescription) in c:\Users\Joel\Documents\GitHub\Swashbuckle\Swashbuckle.Core\Swagger\Filters\ApplyXmlActionComments.cs:line 40
at Swashbuckle.Swagger.SwaggerGenerator.CreateOperation(ApiDescription apiDescription, SchemaRegistry schemaRegistry) in c:\Users\Joel\Documents\GitHub\Swashbuckle\Swashbuckle.Core\Swagger\SwaggerGenerator.cs:line 153
at Swashbuckle.Swagger.SwaggerGenerator.CreatePathItem(IEnumerable`1 apiDescriptions, SchemaRegistry schemaRegistry) in c:\Users\Joel\Documents\GitHub\Swashbuckle\Swashbuckle.Core\Swagger\SwaggerGenerator.cs:line 97
at Swashbuckle.Swagger.SwaggerGenerator.<>c__DisplayClass7.<GetSwagger>b__4(IGrouping`2 group) in c:\Users\Joel\Documents\GitHub\Swashbuckle\Swashbuckle.Core\Swagger\SwaggerGenerator.cs:line 48
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
at Swashbuckle.Swagger.SwaggerGenerator.GetSwagger(String rootUrl, String apiVersion) in c:\Users\Joel\Documents\GitHub\Swashbuckle\Swashbuckle.Core\Swagger\SwaggerGenerator.cs:line 44
at Swashbuckle.Application.SwaggerDocsHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) in c:\Users\Joel\Documents\GitHub\Swashbuckle\Swashbuckle.Core\Application\SwaggerDocsHandler.cs:line 32
at System.Net.Http.HttpMessageInvoker.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Web.Http.Dispatcher.HttpRoutingDispatcher.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Web.Http.HttpServer.<SendAsync>d__0.MoveNext()

Joel

[latenightcoder]

Removing the param element fixes things but it seems like a null check on operation.parameters would be handy.

private static void ApplyParamComments(Operation operation, XPathNavigator methodNode)
        {
            var paramNodes = methodNode.Select(ParameterExpression);
            while (paramNodes.MoveNext())
            {
                var paramNode = paramNodes.Current;
                var parameter = operation.parameters.SingleOrDefault(param => param.name == paramNode.GetAttribute("name", ""));
                if (parameter != null)
                    parameter.description = paramNode.Value.Trim();
            }
        }