从包含冒号 (:) 的查询参数名称中读取值

Question

我收到在 .NET 应用程序中创建新 REST API 的请求，但我不知道如何实现其中一个参数。

我得到了一个Swagger定义，参数定义如下：

如果它只是 eventCreatedDateTime=2021-04-01T14:12:56+01:00 没问题，但它正在获取冒号和等号之间的部分，我不知道如何获取。

基本上，我可以获得 eventCreatedDateTime:gte=2021-04-01T14:12:56+01:00 作为查询字符串参数，我必须阅读 gte 部分并且还能够验证它是否是允许的后缀之一。后缀不是强制性的，因此 eventCreatedDateTime=2021-04-01T14:12:56+01:00 也应该有效。

为了澄清，这是一个查询字符串参数，所以是 URL 的一部分。例如https://example.com/api/mycontroller?param1=value&param2=value&eventCreatedDateTime:gte=2021-04-01T14:12:56+01:00&param4=value

知道如何在 .NET 中执行此操作吗？

Answer 1

为此，我将使用自定义类型，例如：

public class EventCreatedDateTime
{
    public string Operator { get; set; }
    public string Value { get; set; }
}

接下来我将创建一个自定义模型活页夹：

public class EventCreatedDateTimeModelBinderProvider : IModelBinderProvider
{
    public IModelBinder GetBinder(ModelBinderProviderContext context)
    {
        if(context.Metadata.ModelType == typeof(EventCreatedDateTime))
        {
            return new EventCreatedDateTimeModelBinder();
        }
        return null;
    }
}

public class EventCreatedDateTimeModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        foreach(var kvp in bindingContext.HttpContext.Request.Query)
        {
            if (kvp.Key.StartsWith("eventCreatedDateTime:"))
            {
                bindingContext.Result = ModelBindingResult.Success(
                    new EventCreatedDateTime {
                        Operator = kvp.Key.Substring("eventCreatedDateTime:".Length),
                        Value = kvp.Value.First()
                });
            }
        }
        return Task.CompletedTask;
    }
}

我在启动中添加：

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers(options => 
            options.ModelBinderProviders.Insert(0, new EventCreatedDateTimeModelBinderProvider())
        );
        ...
    }
}

那么动作就是：

[HttpGet]
public IActionResult Get(
    string param1,
    string param2,
    EventCreatedDateTime eventCreatedDateTime)
{...}

Answer 2

请参阅 vernou 对 .NET Core 方法的回应。我的环境仍然是框架，所以这是解决方案。

我的自定义类型有点不同，有一个 DateTime 和一个枚举器属性，这当然也可以在 Core 中使用：

public enum Operator
{
    Equals,
    GreaterThenEquals,
    GreaterThen,
    LesserThenEquals,
    LesserThen
}
public class DateTimeFilter
{
    public DateTime? Date { get; set; }
    public Operator Operator { get; set; }
}

框架中的自定义模型绑定器有点不同：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http;
using System.Web.Http.Controllers;
using System.Web.Http.ModelBinding;
using System.Web.Http.ModelBinding.Binders;

namespace CustomModelBinders
{
    public class DateTimeFilterModelBinderProvider : ModelBinderProvider
    {
        private CollectionModelBinderProvider originalProvider = null;

        public DateTimeFilterModelBinderProvider(CollectionModelBinderProvider originalProvider)
        {
            this.originalProvider = originalProvider;
        }

        public override IModelBinder GetBinder(HttpConfiguration configuration, Type modelType)
        {
            IModelBinder originalBinder = originalProvider.GetBinder(configuration, modelType);

            if (originalBinder != null && modelType == typeof(DateTimeFilter))
            {
                return new DateTimeFilterModelBinder();
            }
            return null;
        }
    }

    public class DateTimeFilterModelBinder : IModelBinder
    {
        public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext)
        {
            if (bindingContext.ModelType != typeof(DateTimeFilter))
            {
                return false;
            }
            //Get's the correct key/value from the querystring based on your receiving paramter name.
            //note: you can't use [FromUri(Name = "customName")] with the custom binder so the have to match (partially)
            var query = actionContext.Request.Properties["MS_QueryNameValuePairs"] as ICollection<KeyValuePair<string, string>>;
            KeyValuePair<string, string> kvp = query.First(q => q.Key.Contains(bindingContext.ModelName));
            if (kvp.Key.Contains(":"))
            {
                bindingContext.Model =
                    new DateTimeFilter
                    {
                        Operator = ConvertOperator(kvp.Key.Substring(kvp.Key.IndexOf(":")+1)),
                        Date = ConvertDate(kvp.Value)
                    };
            }
            else
            {
                bindingContext.Model =
                    new DateTimeFilter
                    {
                        Operator = Operator.Equals,
                        Date = ConvertDate(kvp.Value)
                    };
            }
            return true;
        }

        private DateTime? ConvertDate(string str)
        {
            DateTime result;
            DateTimeOffset resultOffset;
            if (DateTime.TryParse(str, out result))
                return result;
            //Apparently the + gets converted into a space, so we need to revert that to have a valid offset
            else if (DateTimeOffset.TryParse(str.Replace(' ', '+'), out resultOffset))
                return resultOffset.ToLocalTime().DateTime;
            else
                return null;
        }

        private Operator ConvertOperator(string str)
        {
            switch (str.ToLowerInvariant())
            {
                case "gte": return Operator.GreaterThenEquals;
                case "gt": return Operator.GreaterThen;
                case "lte": return Operator.LesserThenEquals;
                case "lt": return Operator.LesserThen;
                case "eq": return Operator.Equals;
                default: throw new ArgumentException("Invalid operator");
            }
        }
    }
}

转换方法非常适合在核心应用程序中使用

Framework 中没有启动，参数必须通过属性耦合到绑定器：

[HttpGet]
public IHttpActionResult Get(string param1 = null, string param2 = null, [ModelBinder(typeof(DateTimeFilterModelBinder))] DateTimeFilter eventCreatedDateTime = null, string param3 = null)
{
     //Do Logic
}

以上对于 eventCreatedDateTime=2021-04-01T14:12:56+01:00 按预期工作

例如 eventCreatedDateTime:gte=2021-04-01T14:12:56+01:00

从包含冒号 (:) 的查询参数名称中读取值

Reading a value from a Query parameter name containing a colon (:)

.net

c#

rest

asp.net-web-api