jquery - 将 JQGrid 与 WCF Web 服务结合使用

Question

我正在尝试从我的 ASP.NET 2.0 WebForms 应用程序中运行的 WCF Web 服务获取 JQGrid 的数据。问题在于 WCF Web 服务期望数据格式化为 JSON 字符串，而 JQGrid 正在执行 HTTP Post 并将其作为 Content-Type: application/x-www-form-urlencoded 传递。

虽然返回到 JQGrid 的数据格式似乎有多种选项(它接受 JSON、XML 等)，但似乎没有办法改变它将输入传递到 Web 服务的方式。

所以我试图找出如何调整 WCF 服务以使其接受

Content-Type: application/x-www-form-urlencoded

而不是

Content-Type:"application/json; charset=utf-8"

当我使用 JQuery 进行测试以使用 url 编码发送 Ajax 请求时(如下所示):

$.ajax({
    type: "POST",
    url: "../Services/DocLookups.svc/DoWork",
    data: 'FirstName=Howard&LastName=Pinsley',
    contentType: "Content-Type: application/x-www-form-urlencoded",
    dataType: "json",
    success: function(msg) {
        alert(msg.d);
    }
});

调用失败。使用Fiddler检查流量，发现服务器返回错误:

{"ExceptionDetail":{"HelpLink":null,"InnerException":null,"Message":
"The incoming message has an unexpected message format 'Raw'. The expected
message formats for the operation are 'Xml', 'Json'. This can be because 
a WebContentTypeMapper has not been configured on the binding. 
See the documentation of WebContentTypeMapper for more details."...

请注意，由于编码不同，此代码确实有效

$.ajax({
    type: "POST",
    url: "../Services/DocLookups.svc/DoWork",
    data: '{"FirstName":"Howard", "LastName":"Pinsley"}',
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function(msg) {
        alert(msg.d);
    }
});

在服务器上，服务如下所示:

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(IncludeExceptionDetailInFaults = true)]
public class DocLookups {
    // Add [WebGet] attribute to use HTTP GET

    [OperationContract]
    public string DoWork(string FirstName, string LastName) {
        return "Your name is " + LastName + ", " + FirstName;
    }
}

我的 web.config 包含:

<system.serviceModel>
  <behaviors>
   <endpointBehaviors>
    <behavior name="DocLookupsAspNetAjaxBehavior">
     <enableWebScript />
    </behavior>
   </endpointBehaviors>
  </behaviors>
  <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
  <services>
   <service name="DocLookups">
    <endpoint address="" behaviorConfiguration="DocLookupsAspNetAjaxBehavior"
     binding="webHttpBinding" contract="DocLookups" />
   </service>
  </services>
</system.serviceModel>

感谢您的帮助!

Answer 1

如果您无法控制 ajax 调用，我建议您创建拦截器来覆盖 Content-Type header 。

public class ContentTypeOverrideInterceptor : RequestInterceptor
{
    public string ContentTypeOverride { get; set; }

    public ContentTypeOverrideInterceptor(string contentTypeOverride) : base(true)
    {
        this.ContentTypeOverride = contentTypeOverride;
    }

    public override void ProcessRequest(ref RequestContext requestContext)
    {
        if (requestContext == null || requestContext.RequestMessage == null)
        {
            return;
        }
        Message message = requestContext.RequestMessage;
        HttpRequestMessageProperty reqProp = (HttpRequestMessageProperty)message.Properties[HttpRequestMessageProperty.Name];
        reqProp.Headers["Content-Type"] = ContentTypeOverride;
    }
}

然后，如果您查看 .svc 文件，您将看到 AppServiceHostFactory 类将其更改为包含拦截器

class AppServiceHostFactory : ServiceHostFactory
{
    protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
    {
        var host = new WebServiceHost2(serviceType, true, baseAddresses);
        host.Interceptors.Add(new ContentTypeOverrideInterceptor("application/json; charset=utf-8"));
        return host;
    }
}

这应该适合你。

更新

正如评论中提到的，上述方法适用于 WCF REST 入门套件。如果您仅使用常规 WCF 服务，则必须创建 IOperationBehavior 并将其附加到您的服务。这是行为属性的代码

public class WebContentTypeAttribute : Attribute, IOperationBehavior, IDispatchMessageFormatter
{
    private IDispatchMessageFormatter innerFormatter;
    public string ContentTypeOverride { get; set; }

    public WebContentTypeAttribute(string contentTypeOverride)
    {
        this.ContentTypeOverride = contentTypeOverride;
    }


    // IOperationBehavior
    public void Validate(OperationDescription operationDescription)
    {

    }

    public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation)
    {
        innerFormatter = dispatchOperation.Formatter;
        dispatchOperation.Formatter = this;
    }

    public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation)
    {

    }

    public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters)
    {

    }

    // IDispatchMessageFormatter
    public void DeserializeRequest(Message message, object[] parameters)
    {
        if (message == null)
            return;

        if (string.IsNullOrEmpty(ContentTypeOverride))
            return;

        var httpRequest = (HttpRequestMessageProperty)message.Properties[HttpRequestMessageProperty.Name];
        httpRequest.Headers["Content-Type"] = ContentTypeOverride;
    }

    public Message SerializeReply(MessageVersion messageVersion, object[] parameters, object result)
    {
        return innerFormatter.SerializeReply(messageVersion, parameters, result);
    }
}

您必须修改您的服务契约(Contract)，使其看起来像这样

[OperationContract]
[WebContentType("application/json; charset=utf-8")]
public string DoWork(string FirstName, string LastName)
{
    return "Your name is " + LastName + ", " + FirstName;
}

链接

根据您的要求，这里有一些描述这些 WCF 扩展的链接

• IOperationBehavior Interface
• IDispatchMessageFormatter Interface
• How to get implementation of IDispatchMessageFormatter
• WCF Extensibility - Plugging in custom message processing logic