用法:[HttpPost]public async Task<IActionResult> Post( [FromQuery, RequiredParm] int? Id, [FromQuery] string Company) ActionFilterAttribute:[AttributeUsage(AttributeTargets.Method)]public sealed class CheckRequiredParmAttribute : ActionFilterAttribute{ public override void OnActionExecuting(ActionExecutingContext context) { var requiredParameters = context.ActionDescriptor.Parameters.Where( p => ((ControllerParameterDescriptor)p).ParameterInfo.GetCustomAttribute<RequiredParmAttribute>() != null).Select(p => p.Name); foreach (var parameter in requiredParameters) { if (!context.ActionArguments.ContainsKey(parameter)) { context.ModelState.AddModelError(parameter, $"The required argument '{parameter}' was not found."); } else { foreach (var argument in context.ActionArguments.Where(a => parameter.Equals(a.Key))) { if (argument.Value == null) { context.ModelState.AddModelError(argument.Key, $"The requried argument '{argument.Key}' cannot be null."); } } } } if (!context.ModelState.IsValid) { context.Result = new BadRequestObjectResult(context.ModelState); return; } base.OnActionExecuting(context); }}/// <summary>/// Use this attribute to force a [FromQuery] parameter to be required. If it is missing, or has a null value, model state validation will be executed and returned throught the response./// </summary>[AttributeUsage(AttributeTargets.Parameter)]public sealed class RequiredParmAttribute : Attribute{}Is it possible to validate query parameters on an action without using a model? A lot of the calls in my API are one-offs and I don't see a point in making models for them if they will only be used one time.I saw the following article, which seemed like it was exactly what I needed, except I don't want it to return a 404 if the required parm doesn't exist, I want it to return an object of error messages similar to the baked in model validation - really, I just want the parameters to be treated like a model, without actually having to make a model.https://www.strathweb.com/2016/09/required-query-string-parameters-in-asp-net-core-mvc/[HttpPost]public async Task<IActionResult> Post( [FromQueryRequired] int? Id, [FromQuery] string Company)EDIT:The [FromQueryRequired] is a custom ActionConstraint that throws a 404 if the ID parm is missing (this was taken directly from the article). However I don't want the 404, I want an object that has a message that says {MESSAGE: "ID is required"}. I think the issue is that i can't access the Response context from within an Action Constraint. 解决方案 Here is the solution I ended up using. Add an Attribute to the parms named [RequiredParm]. I loosely based it on someone else's answer for a different question, but I can't seem to find it at the moment, apologies to whoever you are, if I can find it I'll update this answer for credit.EDIT: Found it, answered by @James Law - Web Api Required ParameterUsage:[HttpPost]public async Task<IActionResult> Post( [FromQuery, RequiredParm] int? Id, [FromQuery] string Company)ActionFilterAttribute:[AttributeUsage(AttributeTargets.Method)]public sealed class CheckRequiredParmAttribute : ActionFilterAttribute{ public override void OnActionExecuting(ActionExecutingContext context) { var requiredParameters = context.ActionDescriptor.Parameters.Where( p => ((ControllerParameterDescriptor)p).ParameterInfo.GetCustomAttribute<RequiredParmAttribute>() != null).Select(p => p.Name); foreach (var parameter in requiredParameters) { if (!context.ActionArguments.ContainsKey(parameter)) { context.ModelState.AddModelError(parameter, $"The required argument '{parameter}' was not found."); } else { foreach (var argument in context.ActionArguments.Where(a => parameter.Equals(a.Key))) { if (argument.Value == null) { context.ModelState.AddModelError(argument.Key, $"The requried argument '{argument.Key}' cannot be null."); } } } } if (!context.ModelState.IsValid) { context.Result = new BadRequestObjectResult(context.ModelState); return; } base.OnActionExecuting(context); }}/// <summary>/// Use this attribute to force a [FromQuery] parameter to be required. If it is missing, or has a null value, model state validation will be executed and returned throught the response./// </summary>[AttributeUsage(AttributeTargets.Parameter)]public sealed class RequiredParmAttribute : Attribute{} 这篇关于在.netcore api中不使用模型的情况下验证查询参数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！
