40

使用 ASP.NET Web API。如果参数为空,有没有办法自动返回状态码 400?我发现了这个问题,但这是一个适用于所有方法的全局解决方案,我想在每个方法每个参数的基础上执行此操作。

因此,例如,这就是我目前正在做的事情:

public HttpResponseMessage SomeMethod(SomeNullableParameter parameter)
{
    if (parameter == null)
        throw new HttpResponseException(HttpStatusCode.BadRequest);

    // Otherwise do more stuff.
}

我真的很想做这样的事情(注意 required 属性):

public HttpResponseMessage SomeMethod([Required] SomeNullableParameter parameter)
{
    // Do stuff.
}
4

5 回答 5

23

我最终使用的方法是创建一个我在全球注册的自定义过滤器。过滤器检查所有请求参数RequiredAttribute。如果找到该属性,则检查参数是否随请求一起传递(非空),如果为空,则返回状态代码 400。我还在过滤器中添加了一个缓存来存储每个请求所需的参数,以避免对未来调用的反射命中。我惊喜地发现这也适用于值类型,因为操作上下文将参数存储为对象。

编辑 - 根据 tecfield 的评论更新解决方案

public class RequiredParametersFilter : ActionFilterAttribute
{
    // Cache used to store the required parameters for each request based on the
    // request's http method and local path.
    private readonly ConcurrentDictionary<Tuple<HttpMethod, string>, List<string>> _Cache =
        new ConcurrentDictionary<Tuple<HttpMethod, string>, List<string>>();

    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        // Get the request's required parameters.
        List<string> requiredParameters = this.GetRequiredParameters(actionContext);     

        // If the required parameters are valid then continue with the request.
        // Otherwise, return status code 400.
        if(this.ValidateParameters(actionContext, requiredParameters))
        {
            base.OnActionExecuting(actionContext);
        }
        else
        {
            throw new HttpResponseException(HttpStatusCode.BadRequest);
        }
    }

    private bool ValidateParameters(HttpActionContext actionContext, List<string> requiredParameters)
    {
        // If the list of required parameters is null or containst no parameters 
        // then there is nothing to validate.  
        // Return true.
        if (requiredParameters == null || requiredParameters.Count == 0)
        {
            return true;
        }

        // Attempt to find at least one required parameter that is null.
        bool hasNullParameter = 
            actionContext
            .ActionArguments
            .Any(a => requiredParameters.Contains(a.Key) && a.Value == null);

        // If a null required paramter was found then return false.  
        // Otherwise, return true.
        return !hasNullParameter;
    }

    private List<string> GetRequiredParameters(HttpActionContext actionContext)
    {
        // Instantiate a list of strings to store the required parameters.
        List<string> result = null;

        // Instantiate a tuple using the request's http method and the local path.
        // This will be used to add/lookup the required parameters in the cache.
        Tuple<HttpMethod, string> request =
            new Tuple<HttpMethod, string>(
                actionContext.Request.Method,
                actionContext.Request.RequestUri.LocalPath);

        // Attempt to find the required parameters in the cache.
        if (!this._Cache.TryGetValue(request, out result))
        {
            // If the required parameters were not found in the cache then get all
            // parameters decorated with the 'RequiredAttribute' from the action context.
            result = 
                actionContext
                .ActionDescriptor
                .GetParameters()
                .Where(p => p.GetCustomAttributes<RequiredAttribute>().Any())
                .Select(p => p.ParameterName)
                .ToList();

            // Add the required parameters to the cache.
            this._Cache.TryAdd(request, result);
        }

        // Return the required parameters.
        return result;
    }

}
于 2013-10-11T16:13:53.907 回答
5

在模型中设置[Required]一个属性,然后检查ModelState它是否存在IsValid

这将允许同时测试所有必需的属性。

请参阅“Under-Posting”部分@WebAPI 中的模型验证

于 2013-10-09T18:04:40.307 回答
2

我们可以使用BindRequired来自Microsoft.AspNetCore.Mvc.ModelBinding命名空间的 .

public async Task<ActionResult<IEnumerable<Numbers>>> GetAll([BindRequired, FromQuery]string[] numbers)
        {
            var result = await _service.GetAllDetails(numbers);
            return Ok(result);
        }

之后,您的招摇将如下所示。

在此处输入图像描述

于 2019-11-29T04:20:48.987 回答
2

asp.net core的解决方案...

[AttributeUsage(AttributeTargets.Method)]
public sealed class CheckRequiredModelAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        var requiredParameters = context.ActionDescriptor.Parameters.Where(
            p => ((ControllerParameterDescriptor)p).ParameterInfo.GetCustomAttribute<RequiredModelAttribute>() != null).Select(p => p.Name);

        foreach (var argument in context.ActionArguments.Where(a => requiredParameters.Contains(a.Key, StringComparer.Ordinal)))
        {
            if (argument.Value == null)
            {
                context.ModelState.AddModelError(argument.Key, $"The argument '{argument.Key}' cannot be null.");
            }
        }

        if (!context.ModelState.IsValid)
        {
            var errors = context.ModelState.Values.SelectMany(v => v.Errors).Select(e => e.ErrorMessage);
            context.Result = new BadRequestObjectResult(errors);
            return;
        }

        base.OnActionExecuting(context);
    }
}

[AttributeUsage(AttributeTargets.Parameter)]
public sealed class RequiredModelAttribute : Attribute
{
}

services.AddMvc(options =>
{
    options.Filters.Add(typeof(CheckRequiredModelAttribute));
});

public async Task<IActionResult> CreateAsync([FromBody][RequiredModel]RequestModel request, CancellationToken cancellationToken)
{
    //...
}
于 2017-05-19T13:08:11.283 回答
0

公认的解决方案会自行报告任何错误。MVC5 更合适的方法是让控制器处理(通过模型验证)任何错误的报告,也就是这样:

using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web.Http.Controllers;
using System.Web.Http.Filters;
using System.Web.Http.ModelBinding;

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true)]
public sealed class ValidateParametersAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext context)
    {
        var descriptor = context.ActionDescriptor;
        if (descriptor != null)
        {
            var modelState = context.ModelState;
            foreach (var parameterDescriptor in descriptor.GetParameters())
            {
                EvaluateValidationAttributes(
                    suppliedValue: context.ActionArguments[parameterDescriptor.ParameterName],
                    modelState: modelState,
                    parameterDescriptor: parameterDescriptor
                );
            }
        }

        base.OnActionExecuting(context);
    }

    static private void EvaluateValidationAttributes(HttpParameterDescriptor parameterDescriptor, object suppliedValue, ModelStateDictionary modelState)
    {
        var parameterName = parameterDescriptor.ParameterName;

        parameterDescriptor
            .GetCustomAttributes<object>()
            .OfType<ValidationAttribute>()
            .Where(x => !x.IsValid(suppliedValue))
            .ForEach(x => modelState.AddModelError(parameterName, x.FormatErrorMessage(parameterName)));
    }
}

然后,您可以通过 WebApiConfig.cs 将其普遍插入:

config.Filters.Add(new ValidateParametersAttribute());
于 2018-02-07T19:42:07.647 回答