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  • Can someone explain this block of ASP.NET MVC code to me, please?

    - by Pure.Krome
    Hi folks, this is the current code in ASP.NET MVC2 (RTM) System.Web.Mvc.AuthorizeAttribute class :- public virtual void OnAuthorization(AuthorizationContext filterContext) { if (filterContext == null) { throw new ArgumentNullException("filterContext"); } if (this.AuthorizeCore(filterContext.HttpContext)) { HttpCachePolicyBase cache = filterContext.HttpContext.Response.Cache; cache.SetProxyMaxAge(new TimeSpan(0L)); cache.AddValidationCallback( new HttpCacheValidateHandler(this.CacheValidateHandler), null); } else { filterContext.Result = new HttpUnauthorizedResult(); } } so if i'm 'authorized' then do some caching stuff, otherwise throw a 401 Unauthorized response. Question: What does those 3 caching lines do? cheers :)

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  • Problem with update sql with excel

    - by phenevo
    Hi, I have a problem with this query: Update Provinces Set Provinces.DefaultName=T2.Defaultname from Provinces inner join OPENROWSET('Microsoft.Jet.OLEDB.4.0', 'Excel 8.0;Database=C:\provinces.xlsx;HDR=YES', 'SELECT Code, Defaultname FROM [Arkusz1$]') T2 On Provinces.Code = t2.Code where Provinces.Code = T2.Code I get error: Msg 7399, Level 16, State 1, Line 1 The OLE DB provider "Microsoft.Jet.OLEDB.4.0" for linked server "(null)" reported an error. The provider did not give any information about the error. Msg 7303, Level 16, State 1, Line 1 Cannot initialize the data source object of OLE DB provider "Microsoft.Jet.OLEDB.4.0" for linked server "(null)". What is a reason of this unpleasent situation ?

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  • AJAX Issue, Works in all browsers except IE

    - by Nik
    Alright, this code works in Chrome and FF, but not IE (which is to be expected). Does anyone see anything wrong with this code that would render it useless in IE? var waittime=400; chatmsg = document.getElementById("chatmsg"); room = document.getElementById("roomid").value; sessid = document.getElementById("sessid").value; chatmsg.focus() document.getElementById("chatwindow").innerHTML = "loading..."; document.getElementById("userwindow").innerHTML = "Loading User List..."; var xmlhttp = false; var xmlhttp2 = false; var xmlhttp3 = false; function ajax_read() { if(window.XMLHttpRequest){ xmlhttp=new XMLHttpRequest(); if(xmlhttp.overrideMimeType){ xmlhttp.overrideMimeType('text/xml'); } } else if(window.ActiveXObject){ try{ xmlhttp=new ActiveXObject("Msxml2.XMLHTTP"); } catch(e) { try{ xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } catch(e){ } } } if(!xmlhttp) { alert('Giving up :( Cannot create an XMLHTTP instance'); return false; } xmlhttp.onreadystatechange = function() { if (xmlhttp.readyState==4) { document.getElementById("chatwindow").innerHTML = xmlhttp.responseText; setTimeout("ajax_read()", waittime); } } xmlhttp.open('GET','methods.php?method=r&room=' + room +'',true); xmlhttp.send(null); } function user_read() { if(window.XMLHttpRequest){ xmlhttp3=new XMLHttpRequest(); if(xmlhttp3.overrideMimeType){ xmlhttp3.overrideMimeType('text/xml'); } } else if(window.ActiveXObject){ try{ xmlhttp3=new ActiveXObject("Msxml2.XMLHTTP"); } catch(e) { try{ xmlhttp3=new ActiveXObject("Microsoft.XMLHTTP"); } catch(e){ } } } if(!xmlhttp3) { alert('Giving up :( Cannot create an XMLHTTP instance'); return false; } xmlhttp3.onreadystatechange = function() { if (xmlhttp3.readyState==4) { document.getElementById("userwindow").innerHTML = xmlhttp3.responseText; setTimeout("user_read()", 10000); } } xmlhttp3.open('GET','methods.php?method=u&room=' + room +'',true); xmlhttp3.send(null); } function ajax_write(url){ if(window.XMLHttpRequest){ xmlhttp2=new XMLHttpRequest(); if(xmlhttp2.overrideMimeType){ xmlhttp2.overrideMimeType('text/xml'); } } else if(window.ActiveXObject){ try{ xmlhttp2=new ActiveXObject("Msxml2.XMLHTTP"); } catch(e) { try{ xmlhttp2=new ActiveXObject("Microsoft.XMLHTTP"); } catch(e){ } } } if(!xmlhttp2) { alert('Giving up :( Cannot create an XMLHTTP instance'); return false; } xmlhttp2.open('GET',url,true); xmlhttp2.send(null); } function submit_msg(){ nick = document.getElementById("chatnick").value; msg = document.getElementById("chatmsg").value; document.getElementById("chatmsg").value = ""; ajax_write("methods.php?method=w&m=" + msg + "&n=" + nick + "&room=" + room + "&sessid=" + sessid + ""); } function keyup(arg1) { if (arg1 == 13) submit_msg(); } var intUpdate = setTimeout("ajax_read()", waittime); var intUpdate = setTimeout("user_read()", 0);

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  • Combine query results from one table with the defaults from another

    - by pulegium
    This is a dumbed down version of the real table data, so may look bit silly. Table 1 (users): id INT username TEXT favourite_food TEXT food_pref_id INT Table 2 (food_preferences): id INT food_type TEXT The logic is as follows: Let's say I have this in my food preference table: 1, 'VEGETARIAN' and this in the users table: 1, 'John', NULL, 1 2, 'Pete', 'Curry', 1 In which case John defaults to be a vegetarian, but Pete should show up as a person who enjoys curry. Question, is there any way to combine the query into one select statement, so that it would get the default from the preferences table if the favourite_food column is NULL? I can obviously do this in application logic, but would be nice just to offload this to SQL, if possible. DB is SQLite3...

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  • How to load a configuration file at startup within tomcat

    - by Alex
    I want to be able to load my configuration for the webapp at startup of tomcat (apache commons configuration library) is this a possible way: public class MyAppCfg implements javax.servlet.ServletContextListener { private ServletContext context = null; @Override public void contextInitialized(ServletContextEvent event) { try{ this.context = event.getServletContext(); XMLConfiguration config = new XMLConfiguration("cfg.xml"); config.setReloadingStrategy(new FileChangedReloadingStrategy()); this.context.setAttribute("mycfg", config); } catch (Exception e) { e.printStackTrace(); } } @Override public void contextDestroyed(ServletContextEvent arg0) { this.context = null; } } web.xml <listener> <listener-class>mypackage.MyAppCfg</listener-class> </listener> and later acces them in the webapp via this.cfg = (XMLConfiguration) servletRequest.getAttribute("mycfg");

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  • Why is NavigationHandler.handleNavigation() not forwarding to view ID?

    - by Erik Hermansen
    Inside of a phase listener class that runs during the "RESTORE_VIEW" phase, I have some code like this: public void afterPhase(PhaseEvent event) { FacesContext fc = event.getFacesContext(); NavigationHandler nh = fc.getApplication().getNavigationHandler(); nh.handleNavigation(fc, null, "/a/specific/path/to/a/resource.jspx"); } Navigation to the new URL doesn't work here. The request made will just receive a response from the original JSPX that was navigated to. Code like this works fine: public void afterPhase(PhaseEvent event) { FacesContext fc = event.getFacesContext(); NavigationHandler nh = fc.getApplication().getNavigationHandler(); nh.handleNavigation(fc, null, "OUTCOME_DEFINED_IN_FACES_CONFIG_XML"); } Also the first snippet will work with an IceFaces Faces provider, but not Sun JSF 1.2 which is what I need to use. Is there something I can do to fix the code so it is possible to forward to specific URLs?

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  • Best practice with respect to NPE and multiple expressions on single line

    - by JRL
    I'm wondering if it is an accepted practice or not to avoid multiple calls on the same line with respect to possible NPEs, and if so in what circumstances. For example: getThis().doThat(); vs Object o = getThis(); o.doThat(); The latter is more verbose, but if there is an NPE, you immediately know what is null. However, it also requires creating a name for the variable and more import statements. So my questions around this are: Is this problem something worth designing around? Is it better to go for the first or second possibility? Is the creation of a variable name something that would have an effect performance-wise? Is there a proposal to change the exception message to be able to determine what object is null in future versions of Java ?

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  • Serelization of a class and its sub-class....

    - by Amit
    There is a main class having 2 subClasses(each represent separate entity) and all classes needs to be serialized.. how should I proceed ? My requirement is when I serelize MainClass, I should get the xml for each sub class and main class as well. Thanks in advance... and if my approach is incorrect... correct that as well.. Ex given below... class MainClass { SubClass1 objSubclass1 = null; SubClass2 objSubclass2 = null; public MainClass() { objSubclass1 = new SubClass1(); objSubclass2 = new SubClass2(); } [XmlElement("SubClass1")] public SubClass1 SubClass1 {get {return objSubclass1;} } [XmlElement("SubClass2")] public SubClass2 SubClass2 {get {return objSubclass2;} } } Class SubClass1 { Some properties here... } Class SubClass2 { Some properties here... }

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  • Data not displayed first time in android after copying the file from assets to data folder

    - by Thinkcomplete
    Description I have used the code tip from http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/ to copy a pre-filled data file to the target and handled this in a asynch task Problem : On starting the application it gives error and shuts down first time, starting again without any change it works perfectly fine. So first time after the file is copied, the error comes but after that no issues. Please help Code attached:.. private class CopyDatabase extends AsyncTask<String, Void, Boolean> { private final ProgressDialog dialog = new ProgressDialog(BabyNames.this); protected void onPreExecute() { this.dialog.setMessage("Loading..."); this.dialog.show(); } @Override protected Boolean doInBackground(String... params) { // TODO Auto-generated method stub try { namesDBSQLHelper.createDatabase(); return null; } catch(IOException ioe){ ioe.printStackTrace(); } return null; } protected void onPostExecute(final Boolean success){ if (this.dialog.isShowing()){ this.dialog.dismiss(); } } }

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  • How to handle Application_BeginRequest using a custom filter in asp.net mvc?

    - by denis_n
    How to handle Application_BeginRequest using a custom filter in asp.net mvc? I want to restore session only for one route (~/my-url). I would be cool, if I could create a custom filter and handle that. protected void Application_BeginRequest(object sender, EventArgs e) { var context = HttpContext.Current; if (string.Equals("~/my-url", context.Request.AppRelativeCurrentExecutionFilePath, StringComparison.OrdinalIgnoreCase)) { string sessionId = context.Request.Form["sessionId"]; if (sessionId != null) { HttpCookie cookie = context.Request.Cookies.Get("ASP.NET_SessionId"); if (cookie == null) { cookie = new HttpCookie("ASP.NET_SessionId"); } cookie.Value = sessionId; context.Request.Cookies.Set(cookie); } }

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  • Programming style: should you return early if a guard condition is not satisfied?

    - by John Topley
    One thing I've sometimes wondered is which is the better style out of the two shown below (if any)? Is it better to return immediately if a guard condition hasn't been satisfied, or should you only do the other stuff if the guard condition is satisfied? For the sake of argument, please assume that the guard condition is a simple test that returns a boolean, such as checking to see if an element is in a collection, rather than something that might affect the control flow by throwing an exception. // Style 1 public SomeType aMethod() { SomeType result = null; if (!guardCondition()) { return result; } doStuffToResult(result); doMoreStuffToResult(result); return result; } // Style 2 public SomeType aMethod() { SomeType result = null; if (guardCondition()) { doStuffToResult(result); doMoreStuffToResult(result); } return result; }

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  • Sending JSON collection to ASMX webservice

    - by Mironline
    I have got this json collection in page : var json= { "Elements": [ {"Alignment":null,"Bold":false}, {"Alignment":null,"Bold":false} ], "Front":true, "ThemeID":"9" }; I've generated this JSON in run-time & posted to page. my question is , What is the best solution to send this json to web-service using jQuery. should I use the JSON.stringify method and sent it as as string ? if yes what is the input type in web-service ? can I send it as an object to web-service and set the List<CusomeObject> as input ? in this case how can I implement that ?

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  • [Java] Send cookie with http request problem

    - by nkr1pt
    I'm trying to get a certain cookie in a java client by creating a series of Http requests. It looks like I'm getting a valid cookie from the server but when I'm sending out a request to the fnal url with the seemingly valid cookie I should get some lines of xml in the response but the response is blank because the cookie isw rong or is invalidated because a session has closed or an other problem which I can't figure out. The cookie handed out by the server expires at the end of the session. It seems to me the cookie is valid because when I do the same calls in firefox, a similar cookie with the same name and starting with the 3 first same letters and of the same length is stored in firefox, also expiring at the end of the session. If I then make a request to the final url with only this particular cookie stored in firefox (removed all other cookies), the xml is nicely rendered on the page. Any ideas about what I am doing wrong in this piece of code? One other thing, when I use the value from the very similar cookie generated and strored in firefox in this piece of code, the last request does give xml feedback in the http response! // Validate url = new URL(URL_VALIDATE); conn = (HttpURLConnection) url.openConnection(); conn.setRequestProperty("Cookie", cookie); conn.connect(); String headerName = null; for (int i = 1; (headerName = conn.getHeaderFieldKey(i)) != null; i++) { if (headerName.equals("Set-Cookie")) { if (conn.getHeaderField(i).startsWith("JSESSIONID")) { cookie = conn.getHeaderField(i).substring(0, conn.getHeaderField(i).indexOf(";")).trim(); } } } // Get the XML url = new URL(URL_XML_TOTALS); conn = (HttpURLConnection) url.openConnection(); conn.setRequestProperty("Cookie", cookie); conn.connect(); // Get the response StringBuffer answer = new StringBuffer(); BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); String line; while ((line = reader.readLine()) != null) { answer.append(line); } reader.close(); //Output the response System.out.println(answer.toString())

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  • Conflicting return types

    - by Adi
    I am doing a recursive program and I am getting an error about conflicting types: void* buddyMalloc(int req_size) { // Do something here return buddy_findout(original_index,req_size); // This is the recursive call } void *buddy_findout(int current_index,int req_size) { char *selected = NULL; if(front!=NULL) { if(current_index==original_index) { // Do something here return selected; } else { // Do Something here return buddy_findout(current_index+1,req_size); } } else { return buddy_findout(current_index-1,req_size); } } Error: buddy.c: At top level: buddy.c:76: error: conflicting types for ‘buddy_findout’ buddy.c:72: note: previous implicit declaration of ‘buddy_findout’ was here Please note the file buddy.c in which I am defining this does not contain main and is linked with several other .c files.

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  • SQL syntax problem (multiple selects)

    - by user279521
    I am having problems retrieving accurate data values with my stored proc query below: CREATE PROCEDURE usp_InvoiceErrorLog @RecID int AS DECLARE @ErrorString as varchar(1000), @ErrorCode as int; Select @ErrorCode = ErrorCode from tbl_AcctRecv_WebRpt Where RecID = @RecID; IF NOT(@ErrorCode = NULL) Begin Select @ErrorString = ErrorDesc from tbl_ErrDesc Where ErrorCode = @ErrorCode End Select RecID, VendorNum, VendorName, InvNum, InvTotal, (SELECT CONVERT(VARCHAR(11), InvDate, 106) AS [DD MON YYYY]) As InvDate, TicketRequestor, ErrorCode, @ErrorString as ErrorDesc from tbl_AcctRecv_WebRpt Where RecID = @RecID The ErrorDesc column (in the final select statement at the bottom) returns a NULL value, when it should return a valid string data. Any ideas?

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  • How can I get to the value of my WPF UserControl DependencyProperty from UI Automation Framework?

    - by Surfbutler
    Hi, I'm having trouble getting access to my WPF UserControl DependencyProperty values through the UI Automation Framework. I've used James McCaffreys article in MSDN as a starting point (Automating IO Tests in WPF Applications, MSDN March 2009), but I can only see properties etc in standard controls such as buttons. I'm assuming there's some Automation interface I have to implement on my UserControl, but what and how? I can already see my control fine e.g. in UISpy, but I can't see the dependency properties within it. Here's what my usercontrol looks like currently in UISpy: AutomationElement General Accessibility AccessKey: "" AcceleratorKey: "" IsKeyboardFocusable: "False" LabeledBy: "(null)" HelpText: "Switches 48v Phantom Power On/Off (for Mic inputs only)." State IsEnabled: "True" HasKeyboardFocus: "False" Identification ClassName: "" ControlType: "ControlType.Custom" Culture: "(null)" AutomationId: "V48SwL" LocalizedControlType: "custom" Name: "" ProcessId: "5684 (VirtualSix)" RuntimeId: "7 5684 40026340" IsPassword: "False" IsControlElement: "True" IsContentElement: "True" Visibility BoundingRectangle: "(140, 457, 31, 20)" ClickablePoint: "155,467" IsOffscreen: "False" ControlPatterns

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  • Can i store a Queue in viewstate? only will store the first item i add to queue

    - by Mausimo
    Hey, as the question states i am trying to store a Queue in a viewstate (to track postbacks and refreshes to stop a form from resubmitting). Here is just the viewstate code: private Queue<string> p_tempQue { set { ViewState["sTemp"] = value; } get { return (Queue<string>)ViewState["sTemp"]; } } //BasePage constructor public BasePage() { //create a Queue of string //sTemp = new Queue(); this.Load += new EventHandler(this.Page_Load); this.Init += new EventHandler(this.Page_Init); } //In the 'page_Init' event we have created a simple hidden field by name 'hdnGuid' which is attached to the page on the first hit itself. protected void Page_Init(object sender, EventArgs e) { //initializing the hidden field //create a hidden field with a ID HiddenField hdnGuid = new HiddenField(); hdnGuid.ID = "hdnGuid"; //if it is the first time the page is loaded, create a new guid and assign it as the hidden field value if (!Page.IsPostBack) hdnGuid.Value = Guid.NewGuid().ToString(); //add the hidden field to the page Page.Form.Controls.Add(hdnGuid); } //In the 'page_Load' event we check if the hidden field value is same as the old value. In case the value is not same that means it's a 'postback' //and if the value is same then its 'refresh'. As per situation we set the 'httpContent.Items["Refresh"]' value. protected void Page_Load(object sender, EventArgs e) { if(p_tempQue != null) sTemp = p_tempQue; else sTemp = new Queue<string>(); //The hdnGuid will be set the first time page is loaded, else the hdnGuid //will be set after each time the form is submitted using javascript. //assign the hidden field currently on the page for manipulation HiddenField h1 = (HiddenField)(Page.Form.FindControl("hdnGuid")); //create an instance of the GuidClass GuidClass currentGuid = new GuidClass(); //set the GuidClass Guid property to the value of the hidden field currentGuid.Guid = h1.Value; //check to see if the Queue of strings contains the string which is the current Guid property of the GuidClass //if the are equal, then the page was refreshed if (sTemp.Contains<string>(currentGuid.Guid)) { //adds item as key/value pair to share data between an System.Web.IHttpModule interface and an System.Web.IHttpHandler interface during an HTTP request. System.Web.HttpContext.Current.Items.Add("IsRefresh", true); } //if they are not requal, the page is not refreshed else { //if the current Guid property in the GuidClass is not null or not an empty string //add the new Guid to the Queue if (!(currentGuid.Guid.Equals(null) || currentGuid.Guid.Equals(""))) sTemp.Enqueue(currentGuid.Guid); System.Web.HttpContext.Current.Items.Add("IsRefresh", false); } p_tempQue = sTemp; }

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  • Elapsed time of running a C program

    - by yCalleecharan
    Hi, I would like to know what lines of C code to add to a program so that it tells me the total time that the program takes to run. I guess there should be counter initialization near the beginning of main and one after the main function ends. Is the right header clock.h? Thanks a lot... Update I have a Win Xp machine. Is it just adding clock() at the beginning and another clock() at the end of the program? Then I can estimate the time difference. Yes, you're right it's time.h. Here's my code: #include <stdio.h> #include <stdlib.h> #include <math.h> #include <share.h> #include <time.h> void f(long double fb[], long double fA, long double fB); int main() { clock_t start, end; start = clock(); const int ARRAY_SIZE = 11; long double* z = (long double*) malloc(sizeof (long double) * ARRAY_SIZE); int i; long double A, B; if (z == NULL) { printf("Out of memory\n"); exit(-1); } A = 0.5; B = 2; for (i = 0; i < ARRAY_SIZE; i++) { z[i] = 0; } z[1] = 5; f(z, A, B); for (i = 0; i < ARRAY_SIZE; i++) printf("z is %.16Le\n", z[i]); free(z); z = NULL; end = clock(); printf("Took %ld ticks\n", end-start); printf("Took %f seconds\n", (double)(end-start)/CLOCKS_PER_SEC); return 0; } void f(long double fb[], long double fA, long double fB) { fb[0] = fb[1]* fA; fb[1] = fb[1] - 1; return; } Some errors with MVS2008: testim.c(16) : error C2143: syntax error : missing ';' before 'const' testim.c(18) :error C2143: syntax error : missing ';' before 'type' testim.c(20) :error C2143: syntax error : missing ';' before 'type' testim.c(21) :error C2143: syntax error : missing ';' before 'type' testim.c(23) :error C2065: 'z' : undeclared identifier testim.c(23) :warning C4047: '==' : 'int' differs in levels of indirection from 'void *' testim.c(28) : error C2065: 'A' : undeclared identifier testim.c(28) : warning C4244: '=' : conversion from 'double' to 'int', possible loss of data and it goes to 28 errors. Note that I don't have any errors/warnings without your clock codes. LATEST NEWS: I unfortunately didn't get a good reply here. But after a search on Google, the code is working. Here it is: #include <stdio.h> #include <stdlib.h> #include <math.h> #include <share.h> #include <time.h> void f(long double fb[], long double fA, long double fB); int main() { clock_t start = clock(); const int ARRAY_SIZE = 11; long double* z = (long double*) malloc(sizeof (long double) * ARRAY_SIZE); int i; long double A, B; if (z == NULL) { printf("Out of memory\n"); exit(-1); } A = 0.5; B = 2; for (i = 0; i < ARRAY_SIZE; i++) { z[i] = 0; } z[1] = 5; f(z, A, B); for (i = 0; i < ARRAY_SIZE; i++) printf("z is %.16Le\n", z[i]); free(z); z = NULL; printf("Took %f seconds\n", ((double)clock()-start)/CLOCKS_PER_SEC); return 0; } void f(long double fb[], long double fA, long double fB) { fb[0] = fb[1]* fA; fb[1] = fb[1] - 1; return; } Cheers

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  • Issue using Session in MVC Actions with [authorice]

    - by Pablo Gonzalez
    Hi all, first of all sorry for my poor English! When I use the [Authorice` attribute i can't get Session data that i stored before. For example: public ViewResult Index() { // do some stuffs Session["Test"] = "Hi stackoverflow!"; } And then i try to get it in another action, but with the [Authorize] attibute [Authorize] public ViewResult Test() { // do some stuffs if(Session["Test"] == null) { //do some stuffs } } Session["Test"] is always null, but if i remove the attribute it's work, may anyone help me?, thanks a lot!!! P.S: I instance Session["Test"] in Session_Start

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  • SQL Server 2005: When copy table structure to other database "CONSTRAINT" keywords lost

    - by StreamT
    Snippet of original table: CREATE TABLE [dbo].[Batch]( [CustomerDepositMade] [money] NOT NULL CONSTRAINT [DF_Batch_CustomerDepositMade] DEFAULT (0) Snippet of copied table: CREATE TABLE [dbo].[Batch]( [CustomerDepositMade] [money] NOT NULL, Code for copy database: Server server = new Server(SourceSQLServer); Database database = server.Databases[SourceDatabase]; Transfer transfer = new Transfer(database); transfer.CopyAllObjects = true; transfer.CopySchema = true; transfer.CopyData = false; transfer.DropDestinationObjectsFirst = true; transfer.DestinationServer = DestinationSQLServer; transfer.CreateTargetDatabase = true; Database ddatabase = new Database(server, DestinationDatabase); ddatabase.Create(); transfer.DestinationDatabase = DestinationDatabase; transfer.Options.IncludeIfNotExists = true; transfer.TransferData();

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  • mysql GROUP_CONCAT

    - by user301766
    I want to list all users with their corropsonding user class. Here are simplified versions of my tables CREATE TABLE users ( user_id INT NOT NULL AUTO_INCREMENT, user_class VARCHAR(100), PRIMARY KEY (user_id) ); INSERT INTO users VALUES (1, '1'), (2, '2'), (3, '1,2'); CREATE TABLE classes ( class_id INT NOT NULL AUTO_INCREMENT, class_name VARCHAR(100), PRIMARY KEY (class_id) ); INSERT INTO classes VALUES (1, 'Class 1'), (2, 'Class 2'); And this is the query statement I am trying to use but is only returning the first matching user class and not a concatenated list as hoped. SELECT user_id, GROUP_CONCAT(DISTINCT class_name SEPARATOR ",") AS class_name FROM users, classes WHERE user_class IN (class_id) GROUP BY user_id; Actual Output +---------+------------+ | user_id | class_name | +---------+------------+ | 1 | Class 1 | | 2 | Class 2 | | 3 | Class 1 | +---------+------------+ Wanted Output +---------+---------------------+ | user_id | class_name | +---------+---------------------+ | 1 | Class 1 | | 2 | Class 2 | | 3 | Class 1, Class 2 | +---------+---------------------+ Thanks in advance

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  • Reverse a singly linked list

    - by Madhan
    I would be wondered if there exists some logic to reverse the linked list using only two pointers. The following is used to reverse the single linked list using three pointers namely p, q, r: struct node { int data; struct node *link; }; void reverse() { struct node *p = first, *q = NULL, *r; while (p != NULL) { r = q; q = p; p = p->link; q->link = r; } q = first; } Is there any other alternate to reverse the linked list? what would be the best logic to reverse a singly linked list, in terms of time complexity?

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  • Google Docs iphone library error reporting

    - by phil harris
    I'm in the process of adding a Google Docs interface to my iPhone app, and I'm largely following the example in the GoogleDocs.m file from Tom Saxton's example app. The objective-c library I'm using is from http://code.google.com/p/gdata-objectivec-client/wiki/GDataObjCIntroduction The library file used is from gdata-objectivec-client-1.10.0.zip. This service:username:password method is a slight variant of the one found in the Saxton file GoogleDocs.m starting at line 351: - (void)service:(NSString *)username password:(NSString *)password { if(service == nil) { service = [[[GDataServiceGoogleDocs alloc] init] autorelease]; [service setUserAgent:s_strUserAgent]; [service setShouldCacheDatedData:NO]; [service setServiceShouldFollowNextLinks:NO]; (void)[service authenticateWithDelegate:self didAuthenticateSelector:@selector(ticket:authenticatedWithError:)]; } // update the username/password each time the service is requested if (username != nil && [username length] && password != nil && [password length]) [service setUserCredentialsWithUsername:username password:password]; else [service setUserCredentialsWithUsername:nil password:nil]; } // associated callback for service:username:password: method - (void)ticket:(GDataServiceTicket *)ticket authenticatedWithError:(NSError *)error { NSLog(@"%@",@"authenticatedWithError called"); if(error == nil) [self selectBackupRestore]; else { NSLog(@"error code(%d)", [error code]); NSLog(@"error domain(%d)", [error domain]); NSLog(@"localizedDescription(%@)", error.localizedDescription); NSLog(@"localizedFailureReason(%@)", error.localizedFailureReason); NSLog(@"localizedRecoveryOptions(%@)", error.localizedRecoveryOptions); NSLog(@"localizedRecoverySuggestion(%@)", error.localizedRecoverySuggestion); } } Please note the service:username:password method and the callback compile and run fine. The problem is that the callback is passing a non-nil NSError object. I added an NSLog() for every error reporting attribute of NSError and the (Xcode) log output of a test run is below. [Session started at 2010-05-27 12:27:16 -0700.] 2010-05-27 12:27:38.778 iFilebox[74596:207] authenticatedWithError called 2010-05-27 12:27:38.779 iFilebox[74596:207] error code(-1) 2010-05-27 12:27:38.780 iFilebox[74596:207] error domain(499324) 2010-05-27 12:27:38.781 iFilebox[74596:207] localizedDescription(Operation could not be completed. (com.google.GDataServiceDomain error -1.)) 2010-05-27 12:27:38.782 iFilebox[74596:207] localizedFailureReason((null)) 2010-05-27 12:27:38.782 iFilebox[74596:207] localizedRecoveryOptions((null)) 2010-05-27 12:27:38.783 iFilebox[74596:207] localizedRecoverySuggestion((null)) My essential question is in the error reporting. I was hoping the localizedDescription would be more specific of the error. All I get for the error code value is -1, and the only description of the error is "Operation could not be completed. (com.google.GDataServiceDomain error -1.". Not very helpful. Does anyone know what a GDataServiceDomain error -1 is? Where can I find a full list of all error codes returned, and a description of what they mean?

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  • What's the purpose of GC.SuppressFinalize(this) in Dispose() method?

    - by mr.b
    I have code that looks like this: /// <summary> /// Dispose of the instance /// </summary> public void Dispose() { if (_instance != null) { _instance = null; // Call GC.SupressFinalize to take this object off the finalization // queue and prevent finalization code for this object from // executing a second time. GC.SuppressFinalize(this); } } Although there is a comment that explains purpose of that GC-related call, I still don't understand why it's there. Isn't object destined for garbage collection once all instances cease from existence (like, when used in using() block)? What's the use case scenario where this would play important role? Thanks!

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