ASP.NET WebApi和部分响应

Question

我有一个我正在研究的ASP.NET WebApi项目.老板希望返回支持"部分响应",这意味着尽管数据模型可能包含50个字段,但客户端应该能够为响应请求特定字段.原因是如果他们实现例如列表他们根本不需要所有50个字段的开销,他们可能只想要名字,姓氏和Id来生成列表.到目前为止,我已经使用自定义合约解析器(DynamicContractResolver)实现了一个解决方案,这样当请求进入时,我通过OnActionExecuting方法中的过滤器(FieldListFilter)窥视它,并确定是否有一个名为"FieldList"的字段

一些示例代码

DynamicContractResolver.cs

protected override IList<JsonProperty> CreateProperties(Type type, Newtonsoft.Json.MemberSerialization memberSerialization)
    {
        List<String> fieldList = ConvertFieldStringToList();

        IList<JsonProperty> properties = base.CreateProperties(type, memberSerialization);
        if (fieldList.Count == 0)
        {
            return properties;
        }
        // If we have fields, check that FieldList is one of them.
        if (!fieldList.Contains("FieldList"))
            // If not then add it, FieldList must ALWAYS be a part of any non null field list.
            fieldList.Add("FieldList");
        if (!fieldList.Contains("Data"))
            fieldList.Add("Data");
        if (!fieldList.Contains("FilterText"))
            fieldList.Add("FilterText");
        if (!fieldList.Contains("PageNumber"))
            fieldList.Add("PageNumber");
        if (!fieldList.Contains("RecordsReturned"))
            fieldList.Add("RecordsReturned");
        if (!fieldList.Contains("RecordsFound"))
            fieldList.Add("RecordsFound");
        for (int ctr = properties.Count-1; ctr >= 0; ctr--)
        {
            foreach (string field in fieldList)
            {
                if (field.Trim() == properties[ctr].PropertyName)
                {
                    goto Found;
                }
            }
            System.Diagnostics.Debug.WriteLine("Remove Property at Index " + ctr + " Named: " + properties[ctr].PropertyName);
            properties.RemoveAt(ctr);
        // Exit point for the inner foreach.  Nothing to do here.
        Found: { }
        }
        return properties;
    }

FieldListFilter.cs

public override void OnActionExecuting(System.Web.Http.Controllers.HttpActionContext actionContext)
    {
        if (!actionContext.ModelState.IsValid)
        {
            throw new HttpResponseException(HttpStatusCode.BadRequest);
        }
        // We need to determine if there is a FieldList property of the model that is being used.
        // First get a reference to the model.
        var modelObject = actionContext.ActionArguments.FirstOrDefault().Value;
        string fieldList = string.Empty;
        try
        {
            // Using reflection, attempt to get the value of the FieldList property
            var fieldListTemp = modelObject.GetType().GetProperty("FieldList").GetValue(modelObject);
            // If it is null then use an empty string
            if (fieldListTemp != null)
            {
                fieldList = fieldListTemp.ToString();
            }
        }
        catch (Exception)
        {
            fieldList = string.Empty;
        }

        // Update the global ContractResolver with the fieldList value but for efficiency only do it if they are not the same as the current ContractResolver.
        if (((DynamicContractResolver)GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ContractResolver).FieldList != fieldList)
        {
            GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ContractResolver = new DynamicContractResolver(fieldList);
        }
    }

然后,我可以发送带有json内容有效负载的请求,如下所示:

{
  "FieldList":"NameFirst,NameLast,Id",
  "Data":[
    {
      "Id":1234
    },
    {
      "Id":1235
    }
  ]
}

我会收到这样的答复:

{
  "FieldList":"NameFirst,NameLast,Id",
  "Data":[
    {
      "NameFirst":"Brian",
      "NameLast":"Mueller",
      "Id":1234
    },
    {
      "NameFirst":"Brian",
      "NameLast":"Mueller",
      "Id":1235
    }
  ]
}

我相信使用ContractResolver可能会遇到线程问题.如果我为一个请求更改它,它将对所有请求有效,直到有人在另一个请求上更改它(通过测试似乎是这样)如果是这样的话,那么我认为没有用于我的目的.

总之,我正在寻找一种方法来获得动态数据模型,以便客户端可以根据请求来配置请求的输出.Google在他们的网络API中实现了这一点,他们称之为"部分响应"并且效果很好.我的实现工作到了一定程度,但我担心它会因多个同时请求而中断.

建议？提示？

Answer 1

一个可行的简单解决方案.

使用可为空类型的所有50个成员创建一个模型类.将值分配给请求的成员.只需以正常方式返回结果即可.

在WebApiConfig.Register()中,您必须设置空值处理.

   config.Formatters.JsonFormatter.SerializerSettings =
        new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore };