\n\u5f02\u5e38\u5904\u7406\u6709\u52a9\u4e8e\u6211\u4eec\u5904\u7406\u7cfb\u7edf\u7684\u610f\u5916\u884c\u4e3a\u3002\u4e3a\u4e86\u5904\u7406\u5f02\u5e38\uff0c\u6211\u4eec\u5728\u4ee3\u7801\u4e2d\u4f7f\u7528 try-catch<\/strong> \u5757\u4ee5\u53ca finally<\/strong> \u5173\u952e\u5b57\u6765\u6e05\u7406\u8d44\u6e90\u3002<\/p>\n
Even though there is nothing wrong with the try-catch blocks in our Actions in the Web API project, we can extract all the exception handling logic into a single centralized place. By doing that, we make our actions cleaner, more readable, and the error handling process more maintainable.
\n\u5c3d\u7ba1 Web API \u9879\u76ee\u4e2d\u7684\u64cd\u4f5c\u4e2d\u7684 try-catch \u5757\u6ca1\u6709\u9519\uff0c\u4f46\u6211\u4eec\u53ef\u4ee5\u5c06\u6240\u6709\u5f02\u5e38\u5904\u7406\u903b\u8f91\u63d0\u53d6\u5230\u4e00\u4e2a\u96c6\u4e2d\u7684\u4f4d\u7f6e\u3002\u901a\u8fc7\u8fd9\u6837\u505a\uff0c\u6211\u4eec\u4f7f\u6211\u4eec\u7684\u64cd\u4f5c\u66f4\u5e72\u51c0\uff0c\u66f4\u5177\u53ef\u8bfb\u6027\uff0c\u5e76\u4e14\u9519\u8bef\u5904\u7406\u8fc7\u7a0b\u66f4\u6613\u4e8e\u7ef4\u62a4\u3002<\/p>\n
In this chapter, we are going to refactor our code to use the built-in middleware and our custom middleware for global error handling to demonstrate the benefits of this approach.
\n\u5728\u672c\u7ae0\u4e2d\uff0c\u6211\u4eec\u5c06\u91cd\u6784\u4ee3\u7801\uff0c\u4ee5\u4f7f\u7528\u5185\u7f6e\u4e2d\u95f4\u4ef6\u548c\u81ea\u5b9a\u4e49\u4e2d\u95f4\u4ef6\u8fdb\u884c\u5168\u5c40\u9519\u8bef\u5904\u7406\uff0c\u4ee5\u6f14\u793a\u6b64\u65b9\u6cd5\u7684\u4f18\u52bf\u3002<\/p>\n
5.1 Handing Errors Globally with Built-In Middleware<\/h2>\n
The UseExceptionHandler<\/strong> middleware is a built-in middleware that we can use to handle exceptions. So, let\u2019s dive into the code to see this middleware in action. We are going to create a new ErrorModel<\/strong> folder in the Entities project, and add the new class ErrorDetails in that folder: We are going to use this class for the details of our error message. To continue, in the Extensions folder in the main project, we are going to add a new static class: ExceptionMiddlewareExtensions.cs<\/strong>. Now, we need to modify it: In the code above, we\u2019ve created an extension method in which we\u2019ve registered the UseExceptionHandler<\/strong> middleware. Then, we\u2019ve populated the status code and the content type of our response, logged the error message, and finally returned the response with the custom created object. 5.2 Starpup Class Modification Finally, let\u2019s remove the try-catch<\/strong> block from our code: And there we go. Our action method is much cleaner now. More importantly, we can reuse this functionality to write more readable actions in the future. To inspect this functionality, let\u2019s add the following line to the GetCompanies<\/strong> action, just to simulate an error: And send a request from Postman: We can check our log messages to make sure that logging is working as well. 5 GLOBAL ERROR HANDLING Exception handling helps us deal with the unexpected behavior of our system. To handle exceptions, we use the try-catch block in our code as well as the finally keyword to clean up our resources afterwards. \u5f02\u5e38\u5904\u7406\u6709\u52a9\u4e8e\u6211\u4eec\u5904\u7406\u7cfb\u7edf\u7684\u610f\u5916\u884c\u4e3a\u3002\u4e3a\u4e86\u5904\u7406\u5f02\u5e38\uff0c\u6211\u4eec\u5728\u4ee3\u7801\u4e2d\u4f7f\u7528 try-catch \u5757\u4ee5\u53ca finally \u5173\u952e\u5b57\u6765\u6e05\u7406\u8d44\u6e90\u3002 Even though there is nothing wrong with the try-catch blocks in […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[23],"class_list":["post-163","post","type-post","status-publish","format-standard","hentry","category-csharp","tag-ultimate-asp-net-core-web-api"],"_links":{"self":[{"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/posts\/163","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/diji.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=163"}],"version-history":[{"count":0,"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/posts\/163\/revisions"}],"wp:attachment":[{"href":"https:\/\/diji.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=163"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/diji.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=163"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/diji.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=163"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nUseExceptionHandler<\/strong> \u4e2d\u95f4\u4ef6\u662f\u4e00\u4e2a\u5185\u7f6e\u7684\u4e2d\u95f4\u4ef6\uff0c\u6211\u4eec\u53ef\u4ee5\u7528\u6765\u5904\u7406\u5f02\u5e38\u3002\u56e0\u6b64\uff0c\u8ba9\u6211\u4eec\u6df1\u5165\u7814\u7a76\u4ee3\u7801\uff0c\u770b\u770b\u8fd9\u4e2a\u4e2d\u95f4\u4ef6\u7684\u5b9e\u9645\u6548\u679c\u3002<\/p>\n
\n\u6211\u4eec\u5c06\u5728Entities<\/strong>\u9879\u76ee\u4e2d\u521b\u5efa\u4e00\u4e2a\u65b0\u7684 ErrorModel<\/strong> \u6587\u4ef6\u5939\u9879\u76ee\uff0c\u5e76\u5728\u8be5\u6587\u4ef6\u5939\u4e2d\u6dfb\u52a0\u65b0\u7c7b ErrorDetails<\/strong>\uff1a<\/p>\n\nusing System.Text.Json;\nnamespace Entities.ErrorModel\n{\n public class ErrorDetails \n { \n public int StatusCode { get; set; } \n public string Message { get; set; } \n public override string ToString() => JsonSerializer.Serialize(this);\n }\n}\n<\/pre>\n
\n\u6211\u4eec\u5c06\u4f7f\u7528\u6b64\u7c7b\u6765\u4e86\u89e3\u9519\u8bef\u6d88\u606f\u7684\u8be6\u7ec6\u4fe1\u606f\u3002<\/p>\n
\n\u4e3a\u4e86\u7ee7\u7eed\uff0c\u5728\u4e3b\u9879\u76ee\u7684\u6269\u5c55\u6587\u4ef6\u5939\u4e2d\uff0c\u6211\u4eec\u5c06\u6dfb\u52a0\u4e00\u4e2a\u65b0\u7684\u9759\u6001\u7c7b\uff1aExceptionMiddlewareExtensions.cs<\/strong>\u3002<\/p>\n
\n\u73b0\u5728\uff0c\u6211\u4eec\u9700\u8981\u4fee\u6539\u5b83\uff1a<\/p>\n\nusing Contracts;\nusing Entities.ErrorModel;\nusing Microsoft.AspNetCore.Builder;\nusing Microsoft.AspNetCore.Diagnostics;\nusing Microsoft.AspNetCore.Http;\nusing System.Net;\n\nnamespace CompanyEmployees.Extensions\n{\n public static class ExceptionMiddlewareExtensions {\n public static void ConfigureExceptionHandler(this IApplicationBuilder app, ILoggerManager logger) \n { \n app.UseExceptionHandler(appError => \n { \n appError.Run(async context => {\n context.Response.StatusCode = (int)HttpStatusCode.InternalServerError; \n context.Response.ContentType = "application\/json"; \n var contextFeature = context.Features.Get<IExceptionHandlerFeature>(); \n if (contextFeature != null) \n { \n logger.LogError($"Something went wrong: {contextFeature.Error}"); \n await context.Response.WriteAsync(new ErrorDetails() \n { \n StatusCode = context.Response.StatusCode, \n Message = "Internal Server Error." \n }.ToString()); \n } \n }); \n }); \n } \n }\n}\n<\/pre>\n
\n\u5728\u4e0a\u9762\u7684\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u6269\u5c55\u65b9\u6cd5\uff0c\u5728\u8be5\u65b9\u6cd5\u4e2d\u6ce8\u518c\u4e86 UseExceptionHandler<\/strong> \u4e2d\u95f4\u4ef6\u3002\u7136\u540e\uff0c\u6211\u4eec\u586b\u5145\u4e86\u54cd\u5e94\u7684\u72b6\u6001\u4ee3\u7801\u548c\u5185\u5bb9\u7c7b\u578b\uff0c\u8bb0\u5f55\u4e86\u9519\u8bef\u6d88\u606f\uff0c\u6700\u540e\u8fd4\u56de\u4e86\u5e26\u6709\u81ea\u5b9a\u4e49\u521b\u5efa\u5bf9\u8c61\u7684\u54cd\u5e94\u3002<\/p>\n
\nTo be able to use this extension method, let\u2019s modify the Configure<\/strong> method inside the Startup<\/strong> class:
\n\u4e3a\u4e86\u80fd\u591f\u4f7f\u7528\u6b64\u6269\u5c55\u65b9\u6cd5\uff0c\u8ba9\u6211\u4eec\u4fee\u6539Configure<\/strong> Startup<\/strong> \u7c7b\u4e2d\u7684\u65b9\u6cd5\uff1a<\/p>\n\npublic void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILoggerManager logger)\n {\n if (env.IsDevelopment())\n {\n app.UseDeveloperExceptionPage();\n }\n else\n {\n app.UseHsts();\n }\n\n app.ConfigureExceptionHandler(logger);\n app.UseHttpsRedirection();\n app.UseStaticFiles();\n\n app.UseCors("CorsPolicy");\n app.UseForwardedHeaders(new ForwardedHeadersOptions\n {\n ForwardedHeaders = ForwardedHeaders.All\n });\n\n app.UseRouting();\n\n app.UseAuthorization();\n\n app.UseEndpoints(endpoints =>\n {\n endpoints.MapControllers();\n });\n }\n<\/pre>\n<\/p>\n
\n\u6700\u540e\uff0c\u8ba9\u6211\u4eec\u4ece\u4ee3\u7801\u4e2d\u5220\u9664 try-catch<\/strong> \u5757\uff1a<\/p>\n\nusing AutoMapper;\nusing Contracts;\nusing Entities.DataTransferObjects;\nusing Microsoft.AspNetCore.Mvc;\nusing System;\nusing System.Collections.Generic;\n\nnamespace CompanyEmployees.Controllers\n{\n [Route("api\/companies")]\n [ApiController]\n public class CompaniesController : ControllerBase\n {\n private readonly IRepositoryManager _repository; \n private readonly ILoggerManager _logger; \n private readonly IMapper _mapper; \n public CompaniesController(IRepositoryManager repository, ILoggerManager logger, IMapper mapper) \n { \n _repository = repository; \n _logger = logger; \n _mapper = mapper;\n }\n\n [HttpGet]\n public IActionResult GetCompanies()\n {\n \/\/try\n \/\/{\n \/\/ var companies = _repository.Company.GetAllCompanies(trackChanges: false);\n \/\/ var companiesDto = _mapper.Map<IEnumerable<CompanyDto>>(companies);\n \/\/ return Ok(companiesDto);\n \/\/}\n \/\/catch (Exception ex)\n \/\/{\n \/\/ _logger.LogError($"Something went wrong in the {nameof(GetCompanies)} action {ex}");\n \/\/ return StatusCode(500, "Internal server error");\n \/\/}\n\n var companies = _repository.Company.GetAllCompanies(trackChanges: false); \n var companiesDto = _mapper.Map<IEnumerable<CompanyDto>>(companies); \n return Ok(companiesDto);\n }\n }\n}\n<\/pre>\n
\n\u6211\u4eec\u5c31\u8fd9\u6837\u5427\u3002\u6211\u4eec\u7684\u884c\u52a8\u65b9\u6cd5\u73b0\u5728\u66f4\u5e72\u51c0\u4e86\u3002\u66f4\u91cd\u8981\u7684\u662f\uff0c\u6211\u4eec\u53ef\u4ee5\u91cd\u7528\u6b64\u529f\u80fd\uff0c\u4ee5\u4fbf\u5728\u5c06\u6765\u7f16\u5199\u66f4\u5177\u53ef\u8bfb\u6027\u7684\u64cd\u4f5c\u3002<\/p>\n5.3 Testing the Result<\/h2>\n
\n\u8981\u68c0\u67e5\u6b64\u529f\u80fd\uff0c\u8ba9\u6211\u4eec\u5c06\u4ee5\u4e0b\u884c\u6dfb\u52a0\u5230GetCompanies<\/strong> \u64cd\u4f5c\uff0c\u53ea\u662f\u4e3a\u4e86\u6a21\u62df\u9519\u8bef\uff1a<\/p>\n\nthrow new Exception("Exception");\n<\/pre>\n
\n\u5e76\u53d1\u9001\u90ae\u9012\u5458\u7684\u8bf7\u6c42\uff1a
\nhttps:\/\/localhost:5001\/api\/companies<\/a><\/a><\/a><\/p>\n![\"alt\"](\"\/img\/20220824-ultimate-asp-net-core-web-api\/Image_5001.jpg\")
<\/p>\n
\n\u6211\u4eec\u53ef\u4ee5\u68c0\u67e5\u65e5\u5fd7\u6d88\u606f\uff0c\u4ee5\u786e\u4fdd\u65e5\u5fd7\u8bb0\u5f55\u4e5f\u6b63\u5e38\u5de5\u4f5c\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"