asp.net mvc3 利用ajax实现局部刷新,Asp.net MVC3扩展之Ajax异常处理特性
在Asp.net MVC 3 Web开发中，我们会大量使用各种ajax请求，针对ajax请求如何结何server端如何做异常处理呢？我们可以扩展ActionFilterAttribute，实现一个Ajax异常处理特性。假设您是使用JQuery脚本开发来实现Ajax，看代码:
#region AjaxExceptionAttribute
/// ///Ajax Exception Handle Attribute/// [AttributeUsage(AttributeTargets.Method | AttributeTargets.Class)]
public class AjaxExceptionAttribute : ActionFilterAttribute, IExceptionFilter
{
/// ///Called when an exception occurs./// /// The filter context. public void OnException(ExceptionContext filterContext)
{
if (!filterContext.HttpContext.Request.IsAjaxRequest())
return;
filterContext.Result = AjaxError(filterContext.Exception.Message, filterContext);
//Let the system know that the exception has been handled filterContext.ExceptionHandled = true;
}
/// ///Ajaxes the error./// /// The message./// The filter context./// JsonResult protected JsonResult AjaxError(string message, ExceptionContext filterContext)
{
//If message is null or empty, then fill with generic message if (String.IsNullOrEmpty(message))
message = "Something went wrong while processing your request. Please refresh the page and try again.";
//Set the response status code to 500 filterContext.HttpContext.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
//Needed for IIS7.0 filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
return new JsonResult
{
//can extend more properties Data = new AjaxExceptionModel () { ErrorMessage = message },
ContentEncoding = System.Text.Encoding.UTF8,
JsonRequestBehavior = JsonRequestBehavior.DenyGet
};
}
}
#endregion
/// ///AjaxExceptionModel/// public class AjaxExceptionModel
{
/// ///Gets or sets the error message./// /// ///The error message./// public string ErrorMessage { get; set; }
}
代码已有相关注释。AjaxExceptionModel您完全可以自定义更多的属性，然后在Controller或Action上增加这个特性。 像下面这个HomeController有一个YouKnow的Action，这里为演示我们故意throw一个Exception:
[AjaxException]
public class HomeController : BaseController
{
[HttpPost]
public ActionResult YouKnow(FormCollection fc)
{
throw new ArgumentNullException("YouKnow method: fc should not be null");
}
}
接下来看HTML与JQuery:
ajax post
JQuery的全局AjaxError配置，可参考官方
$("#errorh3info").ajaxError(function (event, request, settings) {
$(this).append("
settings.url:" + settings.url + "");$(this).append("
request.status:" + request.status + "");$(this).append("
request.statusText:" + request.statusText + "");//request.responseText if (request.responseText != "") {
var jsonValue = jQuery.parseJSON(request.responseText);
$(this).append("
ErrorMessage:" + jsonValue.ErrorMessage + "");}
});
给button增加一个Post请求：
$('#inputajax1').click(function () {
$.post('/Home/YouKnow/'
, { id: 1 }
, function (data) {
$('div#right-box.data').html(data);
});
});
这时View上将显示, 我们将看到ErrorMessage是JSON对象的属性：
settings.url:/Home/YouKnow/
request.status:500
request.statusText:error
ErrorMessage:Value cannot be null. Parameter name: YouKnow method: fc should not be null
当然也可以这样:
//ajax post when throw an exception at server side$('#inputajax2').click(function () {
$.ajax({
type: "POST",
url: "/Home/YouKnow2",
data: "fail=1",
dataType: "json",
error: function (xhr, status, error) {
//Show the error $('#lblMethodError').append(xhr.responseText);
$('#lblMethodError').show();
},
success: function (data, textSuccess) {
//show the success message $('#lblMethodSuccess').show();
}
});
});
这时View上，比上面那个请求多显示一条信息, 这是因为我们这里定义了自己error处理callback
{"ErrorMessage":"Value cannot be null.\r\nParameter name: YouKnow method: fc should not be null"}
当我们请求一个不存在Action时呢:
//request undefined url$('#inputajax3').click(function () {
$.post('/Home/YouKnow2233/'
, { id: 1 }
, function (data) {
$('div#right-box.data').html(data);
});
});
页面上将显示：
settings.url:/Home/YouKnow2233/
request.status:0
request.statusText:error
最后我们来看这个ActionFilter的单元测试，这里使用Moq类库:
[TestMethod]
public void Test_Native_AjaxExceptionAttribute()
{
//arrange var header = new System.Collections.Specialized.NameValueCollection();
header.Add("X-Requested-With", "XMLHttpRequest");
var mockRequest = new Mock();
mockRequest.SetupGet(http => http.Headers).Returns(header);
var mockResponse = new Mock();
var mockHttpContext = new Mock();
mockHttpContext.SetupGet(c => c.Request).Returns(mockRequest.Object);
mockHttpContext.SetupGet(c => c.Response).Returns(mockResponse.Object);
var context = mockHttpContext.Object;
var exceptonContextMock = new Mock();
exceptonContextMock.SetupGet(ac => ac.HttpContext).Returns(context);
string errorStr="error";
exceptonContextMock.SetupGet(ec => ec.Exception).Returns(new AggregateException(errorStr));
//act var ajaxAttribute = new AjaxExceptionAttribute();
var exceptionContext = exceptonContextMock.Object;
ajaxAttribute.OnException(exceptionContext);
//verify mockRequest.VerifyAll();
mockResponse.VerifyAll();
mockHttpContext.VerifyAll();
exceptonContextMock.VerifyAll();
//assert var jsonResult = exceptionContext.Result as JsonResult;
Assert.IsNotNull(jsonResult.Data);
Assert.IsTrue(exceptionContext.HttpContext.Request.IsAjaxRequest());
Assert.AreEqual((jsonResult.Data as AjaxExceptionModel).ErrorMessage, errorStr);
Assert.AreEqual(JsonRequestBehavior.DenyGet, jsonResult.JsonRequestBehavior);
Assert.AreEqual(typeof(AggregateException), exceptionContext.Exception.GetType());
}
上面的UnitTest我们Mock HttpContext,HttpRequest,HttpResponse来实现对ActionFilter的测试。
希望您Web开发有帮助。