我有一个正在开发的ASP.NET WebApi项目,老板希望返回结果支持“局部响应”,这意味着虽然数据模型可能包含50个字段,但客户端应该能够请求特定字段的响应。原因是如果他们正在实现例如列表,他们只需要50个字段中的姓、名和ID,而不需要所有50个字段的额外负担。目前,我已经通过使用自定义合同解析器(DynamicContractResolver)来实现解决方案。当请求到达时,我通过OnActionExecuting方法中的过滤器(FieldListFilter)查看它,并确定是否存在名为“FieldList”的字段,如果存在,则用新的DynamicContractResolver实例替换当前ContractResolver,并将字段列表传递给构造函数。
一些示例代码:
DynamicContractResolver.cs
我可以发送一个请求,其中json内容负载如下所示:
我会收到以下类似的响应:
我认为使用ContractResolver可能会遇到线程问题。如果我更改它只针对一个请求,那么在此之后的所有请求中它都有效(通过测试似乎是这样)。如果是这种情况,那么我就不认为它对我的目的有用。
总之,我正在寻找一种动态数据模型的方法,以便客户端可以按照请求的方式配置请求的输出。Google在其Web API中实现了这一点,并称其为“部分响应”,效果很好。我的实现在某种程度上可以工作,但我担心它在多个同时请求时会出现问题。
有什么建议?提示?
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);
}
}
我可以发送一个请求,其中json内容负载如下所示:
{
"FieldList":"NameFirst,NameLast,Id",
"Data":[
{
"Id":1234
},
{
"Id":1235
}
]
}
我会收到以下类似的响应:
{
"FieldList":"NameFirst,NameLast,Id",
"Data":[
{
"NameFirst":"Brian",
"NameLast":"Mueller",
"Id":1234
},
{
"NameFirst":"Brian",
"NameLast":"Mueller",
"Id":1235
}
]
}
我认为使用ContractResolver可能会遇到线程问题。如果我更改它只针对一个请求,那么在此之后的所有请求中它都有效(通过测试似乎是这样)。如果是这种情况,那么我就不认为它对我的目的有用。
总之,我正在寻找一种动态数据模型的方法,以便客户端可以按照请求的方式配置请求的输出。Google在其Web API中实现了这一点,并称其为“部分响应”,效果很好。我的实现在某种程度上可以工作,但我担心它在多个同时请求时会出现问题。
有什么建议?提示?
$select
功能支持:https://aspnetwebstack.codeplex.com/wikipage?title=%24select%20and%20%24expand%20support&referringTitle=Specs - KiranDynamicContractResolver
的新实例并将其用作ContractResolver
,那么就不应该出现并发问题。 - muratgu