Dojo Error Handling
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Introduction¶ The dojo.xhrGet() function is the cornerstone function of AJAX development. Its purpose is to provide an easy to use and consistent interface to making asynchronous calls to retrieve data. This API is an abstraction atop the
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browser's XMLHttpRequest object and makes usage the same regardless of which browser your application ajax error handling is running on. This makes it much simpler to write cross-browser compatible AJAX style applications. This function, in essence, implements making an
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HTTP ‘GET' call. The following information should get you up and going with dojo.xhrGet(). As with all dojo functions, always refer to the API docs for detailed information. Limitations¶ dojo.xhrGet (and other functions in the same dojo xhrpost error handling line: dojo.xhrPost, dojo.xhrDelete, dojo.xhrPut), are bound by the ‘same domain' security policy of the browser. This means that they can only establish a connection back to the same server that served the HTML page. If you wish to use this API to talk to servers other than the one that originated your page, then you will have to use a proxy on your originating server and have it forward the requests. The dgrid error handling only other solution to working around the same domain restriction is to use alternate IO methods, such as dojo.io.script. Usage¶ The xhrGet() function takes an object as its parameter. This object defines how the xhrGet should operate. Minimally, this object must contain a ‘url' attribute so that the function knows where to send the request. Having just a ‘url' attribute isn't the most useful approach to calling the function, though. You can also embed information such as how to handle the return data (As XML, JSON, or text), and what do do when it completes. It also accepts other useful parameters such as ‘preventCache', and ‘sync', which alter its behavior slightly. For a reasonable list of all the options it supports, see the following table: dojo.xhrGet supported object properties¶ url The URL to request data from. This URL must go to the same server that originated the page or it will fail the load. This is due to the same domain browser security restriction. handleAs This parameter specifies how to handle the data returned from the server. It usually takes values of ‘text', ‘xml', or ‘json'. What those values do is instruct it to try and hand the data to the asynchronous callback functions in that format. Naturally if you specify a format that
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Dojo Xhr Error Handling
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helping each other. Join them; it only takes a minute: Sign up Dojo error handling in ajax methods up vote 3 down vote favorite Under what conditions does error of xhr methods get called? Even when the response http://dojotoolkit.org/reference-guide/dojo/xhrGet.html is 200, the code in error is called. I'm using the xhrPost method. Update: dojo.xhrPost({ url: url, handleAs: respType /* json */, content: data, load: onServerResponse, error: onHttpError }) function onServerResponse(response, ioArgs) { if(onResponse !== null) { onResponse(response); } } function onHttpError(error, ioArgs) { if (showHttpError === true) { var errMsg = ""; switch (ioArgs.xhr.status) { case 0: errMsg = "Please check Web Server status."; break; case 404: errMsg = "HTTP (404): Requested Page Not Found"; break; http://stackoverflow.com/questions/8553590/dojo-error-handling-in-ajax-methods case 500: errMsg = "HTTP (500): The server reported an Error"; break; default: errMsg = "Unhandled HTTP error - " + ioArgs.xhr.status; } ConsoleUtils.showNotificationAlertDialog(errMsg, ConsoleConstants.INFORMATION); } } These are the response headers from Firebug: Server Apache-Coyote/1.1 Content-Type application/json;charset=UTF-8 Transfer-Encoding chunked Date Sun, 18 Dec 2011 18:06:54 GMT The response body {"message":"Kiosk successfully deleted","success":true} Despite a return status of 200, the alert dialog is called. dojo share|improve this question edited Oct 14 '13 at 12:38 Danubian Sailor 14.2k1993164 asked Dec 18 '11 at 17:57 Deepak Marur 241823 possible duplicate of What is considered and AJAX request error (in Dojo)? –hugomg Dec 18 '11 at 18:00 Thanks for the info. I've updated my question with the code snippets and firebug contents. –Deepak Marur Dec 18 '11 at 18:51 Can you post your onResponse method ? –Philippe Dec 19 '11 at 11:15 Check that your onServerResponse method doesn't throw an error. –McDowell Dec 19 '11 at 11:22 1 I guess the error comes after the first 200 status... when you invoke onResponse(response); –Philippe Dec 19 '11 at 18:41 | show 2 more comments 2 Answers 2 active oldest votes up vote 0 down vote in your onServerResponse function you use a var called onResponse. Since you're doing : onResponse() i can only guess onResponse is a function. Then your test if(onRespon
10:10 am A common scenario with web applications is accessing protected resources, which require authentication with the server in order to proceed. A common flow is as https://www.sitepen.com/blog/2015/01/21/faq-how-can-i-handle-recoverable-server-errors-transparently-with-dojorequest/ follows: User opens web site Web site presents authentication screen User enters http://earlhood.blogspot.com/2009/08/providing-meaningful-errors-in-dojoxhr.html credentials Web site presents protected information Authentication workflows This is simple enough to begin with, but what happens when the session times out? Or perhaps the application does not require authentication initially, but once the user initiates an action to access protected resources authentication is required? A common approach error handling is to use redirects to an authentication page: User's authentication session times out Any action on user's part redirects to authentication screen After successful authentication, user is redirected to the results of the initial action This model works well enough with applications architected around the full page request-response model, but becomes less pleasant with single-page applications that provide a persistent and responsive dojo error handling user interface. A solution that provides a better end-user experience is to mimic the general approach above without the actual page redirects. The authentication can be performed without causing a full page reload: User's authentication session times out (assume client-side application code has no knowledge of session status) User initiates an action which is handled normally by the application code and makes an XHR request to the server The server detects that the session has timed out and instead of returning the requested resource it returns a 403 (Forbidden) status code Client-side application code has been configured to intercept all 403 responses and present an authentication dialog User provides credentials and re-authenticates Initial request is repeated; server returns appropriate resource; application flow continues as normal Emulating redirects client-side The challenge is, how can step #4 be implemented using dojo/request? By creating your own request provider you can set up a robust system that works across your application without having to update code in individual application components. Let's look at what we need to do in a little more detail. The goal is to provid
dojo.xhr calls I've been working with Dojo lately, and one problem is the useless error messages one gets back from the server, especially when using dojo.xhr. The problem is that the response body from the server is generally some large HTML message that may not be useful for display purposes in an AJAX-based calling environment.To remedy this, I made some modifications to the server-side (implemented in Java servlets) to capture exceptions and return a JSON structure if the request is an AJAX request. This makes it easier for the Javascript code to process error text more easily.On the client-side, I have some basic utility functions to facilitate capturing/reporting errors from dojo.xhr calls.First, the server-side:Before I Start:Before providing detail, I should note that I've created a base servletclass that all my servlets sub-class. This allows me to centralizeoperations and services for all my servlets. In the context of this post,this becomes useful for the purposes of exception handling. The baseclass checks all exceptions from sub-classes allowing centralizationof error handling based upon the type of exception that occurred.I also have a custom request object to encapsulate the HttpServletRequestand HttpServletResponse objects. This encapsulation allows me to addsupport for additional capabilities beyond the standard servlet APIrelated to request/response. For example, I provide file-upload supportand still provide a single consistent interface for servlets to accessrequest parameters.Some of the code provided here may contain references to custom classes Iuse, but I believe they are self-explanatory.How to detect an AJAX request: public boolean isAjaxRequest() { String reqwith = req.getHeader("x-requested-with"); if (StringUtil.isBlank(reqwith)) return false; if (reqwith.toLowerCase().equals("xmlhttprequest")) return true; return false; }The above works for most cases, and wrt Dojo, definitely workssince Dojo sets the proper request headers.Capturing Servlet Exceptions:In my base servlet class, I catch all exceptions: } catch (Exception e) { if (r.isAjaxRequest()) { log.error("Exception caught for AJAX request: "+e, e); sendJSONError(resp, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e.getMessage()); } else { if (e instanceof ServletException) { throw (ServletException)e; } throw new ServletException(e.getMessage(), e); } }I check if the request in an AJAX request, and if so, utilize the sendJSONE