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  • How to implement callback functions inside classes (PHP)

    - by sombe
    I need to use a class callback method on an array inside another method (the callback function belongs to the class). class Database { public function escape_string_for_db($string){ return mysql_real_escape_string($string); } public function escape_all_array($array){ return array_filter($array,"$this->escape_string_for_db"); } } Is this the right way to go about that? (I mean, in terms of the second parameter passed to array_filter)

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  • Problem with generics

    - by jess
    I have this code in base class protected virtual bool HasAnyStuff<TObject>(TObject obj) where TObject:class { return false; } In child class I am overriding protected override bool HasAnyStuff<Customer>(Customer obj) { //some stuff if Customer.sth etc return false; } I am getting this error '''Type parameter declaration must be an identifier not a type''' What is it I am doing wrong here?

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  • .split("1px") into ["1px",1,"px"] in Javascript

    - by Jay
    I'm rubbish at Regular Expressions, really! What I'd like is to split a string containing a CCS property value into an array of [string,value,unit]. For example: if I supplied the .split() method with 1px it'd return ["1px",1,"px"]. If I were to supply, similarly, 10% it'd return ["10%",10,"%"]. Can this be done? I appreciate all your help!

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  • Rule of precedence == over =

    - by robUK
    Hello, I am just wondering would it be better to do this: if((fd = open(filename, O_RDWR)) == -1) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } or this fd = open(filename, O_RDWR); if(fd == -1) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } Many thanks for any suggestions,

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  • unprotected access to member in property get

    - by Lenik
    I have a property public ObservableCollection<string> Name { get { return _nameCache; } } _nameCache is updated by multiple threads in other class methods. The updates are guarded by a lock. The question is: should I use the same lock around my return statement? Will not using a lock lead to a race condition?

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  • Python how to convert this for loop into a while loop

    - by user1690198
    I have this for a for loop which I made I was wondering how I would write so it would work with a while loop. def scrollList(myList): negativeIndices=[] for i in range(0,len(myList)): if myList[i]<0: negativeIndices.append(i) return negativeIndices So far I have this def scrollList2(myList): negativeIndices=[] i= 0 length= len(myList) while i != length: if myList[i]<0: negativeIndices.append(i) i=i+1 return negativeIndices

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  • Object allocation in C++

    - by Poiuyt
    char *myfunc() { char *temp = "string"; return temp; } In this piece of code, where does the allocation of the object pointed to by temp happen and what would be its scope? Is this function a valid way to return a char* pointer?

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  • How to find where error is.

    - by gurugio
    How can I find where the error occurs? In C language, the return value means what error occurs, such as failure to open file or memory allocation. There is no information where the error occurs. For example, function 'foo' calls A,B,C,D. If foo returns an error value, it might be return value of A or B or C or D. I cannot find what function returns error. I have to run debugger or add some codes to find what function returns error.

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  • Java Sorting "queue" list based on DateTime and Z Position (part of school project)

    - by Kuchinawa
    For a school project i have a list of 50k containers that arrive on a boat. These containers need to be sorted in a list in such a way that the earliest departure DateTimes are at the top and the containers above those above them. This list then gets used for a crane that picks them up in order. I started out with 2 Collection.sort() methods: 1st one to get them in the right XYZ order Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { return positionSort(contData1.getLocation(),contData2.getLocation()); } }); Then another one to reorder the dates while keeping the position in mind: Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { int c = contData1.getLeaveDateTimeFrom().compareTo(contData2.getLeaveDateTimeFrom()); int p = positionSort2(contData1.getLocation(), contData2.getLocation()); if(p != 0) c = p; return c; } }); But i never got this method to work.. What i got working now is rather quick and dirty and takes a long time to process (50seconds for all 50k): First a sort on DateTime: Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { return contData1.getLeaveDateTimeFrom().compareTo(contData2.getLeaveDateTimeFrom()); } }); Then a correction function that bumps top containers up: containers = stackCorrection(containers); private static List<ContainerData> stackCorrection(List<ContainerData> sortedContainerList) { for(int i = 0; i < sortedContainerList.size(); i++) { ContainerData current = sortedContainerList.get(i); // 5 = Max Stack (0 index) if(current.getLocation().getZ() < 5) { //Loop through possible containers above current for(int j = 5; j > current.getLocation().getZ(); --j) { //Search for container above for(int k = i + 1; k < sortedContainerList.size(); ++k) if(sortedContainerList.get(k).getLocation().getX() == current.getLocation().getX()) { if(sortedContainerList.get(k).getLocation().getY() == current.getLocation().getY()) { if(sortedContainerList.get(k).getLocation().getZ() == j) { //Found -> move container above current sortedContainerList.add(i, sortedContainerList.remove(k)); k = sortedContainerList.size(); i++; } } } } } } return sortedContainerList; } I would like to implement this in a better/faster way. So any hints are appreciated. :)

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  • make select @@IDENTITY; a long?

    - by acidzombie24
    I am grabbing the last rowid and i am doing this select @@IDENTITY pk = (long)cmd.ExecuteScalar(); I get an invalid typecast bc this is int instead of long. Why doesnt this return a long? can i make it return long? Solution for now is to use pk = Convert.ToInt64(cmd.ExecuteScalar());

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  • SELECT DISTINCT multiple field search?

    - by Patrick
    I'm trying to search multiple fields zc_city and zc_zip for when user input and then return row results for zc_city zc_state and zc_zip $q = strtolower($_GET["q"]); if (!$q) return; $sql = "SELECT DISTINCT zc_city AS zcity FROM search_zipcodes WHERE zc_city LIKE '$q%'"; $rsd = mysql_query($sql); while($rs = mysql_fetch_array($rsd)) { $zcity = $rs['zcity']; echo "$zcity\n"; }

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  • [Linq to sql] query result what should i use Count() or Any()...

    - by Pandiya Chendur
    I am checking login of a user by this repository method, public bool getLoginStatus(string emailId, string password) { var query = from r in taxidb.Registrations where (r.EmailId == emailId && r.Password==password) select r; if (query.Count() != 0) { return true; } return false; } I saw in one of the previous questions !query.Any() would be faster... Which should i use? Any suggestion....

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  • How to detect invalid image URL with JAVA?

    - by Cataclysm
    I have a method to download image from URL. As like below.. public static byte[] downloadImageFromURL(final String strUrl) { InputStream in; ByteArrayOutputStream out = new ByteArrayOutputStream(); try { URL url = new URL(strUrl); in = new BufferedInputStream(url.openStream()); byte[] buf = new byte[2048]; int n = 0; while (-1 != (n = in.read(buf))) { out.write(buf, 0, n); } out.close(); in.close(); } catch (IOException e) { return null; } return out.toByteArray(); } I have an image url and it is valid. for example. https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTxfYM-hnD-Z80tgWdIgQKchKe-MXVUfTpCw1R5KkfJlbRbgr3Zcg My problem is I don't want to download if image is really not exists.Like .... https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTxfYM-hnD-Z80tgWdIgQKchKe-MXVUfTpCw1R5KkfJlbRbgr3Zcgaaaaabbbbdddddddddddddddddddddddddddd This image shouldn't be download by my method. So , how can I know the giving image URL is not really exists. I don't want to validate my URL (I think that may not my solution ). So, I googled for that. From this article ... How to check if a URL exists or returns 404 with Java? and Java check if file exists on remote server using its url But this con.getResponseCode() will always return status code "200". This mean my method will also download invalid image urls. So , I output my bufferStream as like... System.out.println(in.read(buf)); Invalid image URL produces "43". So , I add these lines of codes in my method. if (in.read(buf) == 43) { return null; } It is ok. But I don't think that will always satisfy. Has another way to get it ? am I right? I would really appreciate any suggestions. This problem may struct my head. Thanks for reading my question.

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  • how to search a string in structure variable ( C# )

    - by deep
    public struct Items { public string Id; public string Name; } public Items[] _items = null; if (_items.Contains("Table")) { // i need to check the structure and need to return correponding id } and am having a list of variables in my structure variable... i need to search a Name in the structure(_items) and i want to return the Corresponding Id. how to do this,

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  • How to add MousePressEvent?

    - by John Son
    In qt: I create a class based on QToolButton to display icon and text. How can I add 'mousePressEvent' to the class? Thank you. bool IconLabel::event (QEvent* e ) { if ( e->type() == QEvent::Paint) { return QToolButton::event(e); } return true; } The class is: class IconLabel : public QToolButton { Q_OBJECT public: explicit IconLabel(QWidget *parent = 0); bool event (QEvent* e ); signals: public slots: };

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  • Do these methods have same output?

    - by devrimbaris
    protected synchronized boolean isTimeoutOccured(Duration timeoutDuration) { DateTime now = new DateTime(); if (timeoutOccured == false) { if (new Duration(requestTime.getMillis(), now.getMillis()).compareTo(timeoutDuration) > 0) { timeoutOccured = true; } } return timeoutOccured; } protected boolean isTimeoutOccured2(Duration timeoutDuration) { return atomicTimeOut.compareAndSet(false, new Duration(requestTime.getMillis(), new DateTime().getMillis()).compareTo(timeoutDuration) > 0); }

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  • IO::Pipe - close(<handle>) does not set $?

    - by danboo
    My understanding is that closing the handle for an IO::Pipe object should be done with the method ($fh->close) and not the built-in (close($fh)). The other day I goofed and used the built-in out of habit on a IO::Pipe object that was opened to a command that I expected to fail. I was surprised when $? was zero, and my error checking wasn't triggered. I realized my mistake. If I use the built-in, IO:Pipe can't perform the waitpid() and can't set $?. But what I was surprised by was that perl seemed to still close the pipe without setting $? via the core. I worked up a little test script to show what I mean: use 5.012; use warnings; use IO::Pipe; say 'init pipes:'; pipes(); my $fh = IO::Pipe->reader(q(false)); say 'post open pipes:'; pipes(); say 'return: ' . $fh->close; #say 'return: ' . close($fh); say 'status: ' . $?; say q(); say 'post close pipes:'; pipes(); sub pipes { for my $fd ( glob("/proc/self/fd/*") ) { say readlink($fd) if -p $fd; } say q(); } When using the method it shows the pipe being gone after the close and $? is set as I expected: init pipes: post open pipes: pipe:[992006] return: 1 status: 256 post close pipes: And, when using the built-in it also appears to close the pipe, but does not set $?: init pipes: post open pipes: pipe:[952618] return: 1 status: 0 post close pipes: It seems odd to me that the built-in results in the pipe closure, but doesn't set $?. Can anyone help explain the discrepancy? Thanks!

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  • toFixed(2) - math round ?

    - by adrien334
    Hi, I would like to find a function that will return this kind of formatted values : 1.5555 => 1.55 1.5556 => 1.56 1.5554 => 1.55 1.5651 => 1.56 toFixed() and math round return this value : 1.5651.fixedTo(2) => 1.57 This will be usefull for money rounding.

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  • Why can a List(Of SomeObject) not be converted to an IEnumerable(Of ISomeInterface) while SomeObject

    - by ropstah
    Please see the last comment in GetListChildren() function. "Why can a List(Of Page) not be converted to an IEnumerable(Of IListHasChildren) ?" Interface IListHasChildren Function GetListChildren() as IEnumerable(Of IListHasChildren) End Interface Public Class Page : Implements IListHasChildren Public Function GetChildren() As List(Of Page) //'return List(Of Page) with children End Function Public Function GetListChildren() : Implements IListHasChildren.GetListChildren Return Me.GetChildren() //'This cannot be converted to IEnumerable(Of IListHasChildren) ?? End Function End Class

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  • Mobile enabled web apps with ASP.NET MVC 3 and jQuery Mobile

    - by shiju
    In my previous blog posts, I have demonstrated a simple web app using ASP.NET MVC 3 and EF Code First. In this post, I will be focus on making this application for mobile devices. A single web site will be used for both mobile browsers and desktop browsers. If users are accessing the web app from mobile browsers, users will be redirect to mobile specific pages and will get normal pages if users are accessing from desktop browsers. In this demo app, the mobile specific pages are maintained in an ASP.NET MVC Area named Mobile and mobile users will be redirect to MVC Area Mobile. Let’s add a new area named Mobile to the ASP.NET MVC app. For adding Area, right click the ASP.NET MVC project and  select Area from Add option. Our mobile specific pages using jQuery Mobile will be maintained in the Mobile Area. ASP.NET MVC Global filter for redirecting mobile visitors to Mobile area Let’s add an ASP.NET MVC Global filter for redirecting mobile visitors to Mobile area. The below Global filter is taken from the sample app http://aspnetmobilesamples.codeplex.com/ created by the ASP.NET team. The below filer will redirect the Mobile visitors to an ASP.NET MVC Area Mobile. public class RedirectMobileDevicesToMobileAreaAttribute : AuthorizeAttribute     {         protected override bool AuthorizeCore(System.Web.HttpContextBase httpContext)         {             // Only redirect on the first request in a session             if (!httpContext.Session.IsNewSession)                 return true;               // Don't redirect non-mobile browsers             if (!httpContext.Request.Browser.IsMobileDevice)                 return true;               // Don't redirect requests for the Mobile area             if (Regex.IsMatch(httpContext.Request.Url.PathAndQuery, "/Mobile($|/)"))                 return true;               return false;         }           protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)         {             var redirectionRouteValues = GetRedirectionRouteValues(filterContext.RequestContext);             filterContext.Result = new RedirectToRouteResult(redirectionRouteValues);         }           // Override this method if you want to customize the controller/action/parameters to which         // mobile users would be redirected. This lets you redirect users to the mobile equivalent         // of whatever resource they originally requested.         protected virtual RouteValueDictionary GetRedirectionRouteValues(RequestContext requestContext)         {             return new RouteValueDictionary(new { area = "Mobile", controller = "Home", action = "Index" });         }     } Let’s add the global filer RedirectMobileDevicesToMobileAreaAttribute to the global filter collection in the Application_Start() of Global.asax.cs file   GlobalFilters.Filters.Add(new RedirectMobileDevicesToMobileAreaAttribute(), 1); Now your mobile visitors will be redirect to the Mobile area. But the browser detection logic in the RedirectMobileDevicesToMobileAreaAttribute filter will not be working in some modern browsers and some conditions. But the good news is that ASP.NET’s browser detection feature is extensible and will be greatly working with the open source framework 51Degrees.mobi. 51Degrees.mobi is a Browser Capabilities Provider that will be working with ASP.NET’s Request.Browser and will provide more accurate and detailed information. For more details visit the documentation page at http://51degrees.codeplex.com/documentation. Let’s add a reference to 51Degrees.mobi library using NuGet We can easily add the 51Degrees.mobi from NuGet and this will update the web.config for necessary configuartions. Mobile Web App using jQuery Mobile Framework jQuery Mobile Framework is built on top of jQuery that provides top-of-the-line JavaScript in a unified User Interface that works across the most-used smartphone web browsers and tablet form factors. It provides an easy way to develop user interfaces for mobile web apps. The current version of the framework is jQuery Mobile Alpha 3. We need to include the following files to use jQuery Mobile. The jQuery Mobile CSS file (jquery.mobile-1.0a3.min.css) The jQuery library (jquery-1.5.min.js) The jQuery Mobile library (jquery.mobile-1.0a3.min.js) Let’s add the required jQuery files directly from jQuery CDN . You can download the files and host them on your own server. jQuery Mobile page structure The basic jQuery Mobile page structure is given below <!DOCTYPE html> <html>   <head>   <title>Page Title</title>   <link rel="stylesheet" href="http://code.jquery.com/mobile/1.0a3/jquery.mobile-1.0a1.min.css" />   <script src="http://code.jquery.com/jquery-1.5.min.js"></script>   <script src="http://code.jquery.com/mobile/1.0a3/jquery.mobile-1.0a3.min.js"></script> </head> <body> <div data-role="page">   <div data-role="header">     <h1>Page Title</h1>   </div>   <div data-role="content">     <p>Page content goes here.</p>      </div>   <div data-role="footer">     <h4>Page Footer</h4>   </div> </div> </body> </html> The data- attributes are the new feature of HTML5 so that jQuery Mobile will be working on browsers that supporting HTML 5. You can get a detailed browser support details from http://jquerymobile.com/gbs/ . In the Head section we have included the Core jQuery javascript file and jQuery Mobile Library and the core CSS Library for the UI Element Styling. These jQuery files are minified versions and will improve the performance of page load on Mobile Devices. The jQuery Mobile pages are identified with an element with the data-role="page" attribute inside the <body> tag. <div data-role="page"> </div> Within the "page" container, any valid HTML markup can be used, but for typical pages in jQuery Mobile, the immediate children of a "page" are div element with data-roles of "header", "content", and "footer". <div data-role="page">     <div data-role="header">...</div>     <div data-role="content">...</div>     <div data-role="footer">...</div> </div> The div data-role="content" holds the main content of the HTML page and will be used for making user interaction elements. The div data-role="header" is header part of the page and div data-role="footer" is the footer part of the page. Creating Mobile specific pages in the Mobile Area Let’s create Layout page for our Mobile area <!DOCTYPE html> <html> <head>     <title>@ViewBag.Title</title>     <link rel="stylesheet" href="http://code.jquery.com/mobile/1.0a3/jquery.mobile-1.0a3.min.css" />     <script src="http://code.jquery.com/jquery-1.5.min.js"></script>     <script src="http://code.jquery.com/mobile/1.0a3/jquery.mobile-1.0a3.min.js"></script>     </head>      <body> @RenderBody()    </body> </html> In the Layout page, I have given reference to jQuery Mobile JavaScript files and the CSS file. Let’s add an Index view page Index.chtml @{     ViewBag.Title = "Index"; } <div data-role="page"> <div data-role="header">      <h1>Expense Tracker Mobile</h1> </div> <div data-role="content">   <ul data-role="listview">     <li>@Html.Partial("_LogOnPartial")</li>      <li>@Html.ActionLink("Home", "Index", "Home")</li>      <li>@Html.ActionLink("Category", "Index", "Category")</li>                          <li>@Html.ActionLink("Expense", "Index", "Expense")</li> </ul> </div> <div data-role="footer">           Shiju Varghese | <a href="http://weblogs.asp.net/shijuvarghese">Blog     </a> | <a href="http://twitter.com/shijucv">Twitter</a>   </div> </div>   In the Index page, we have used data-role “listview” for showing our content as List View Let’s create a data entry screen create.cshtml @model MyFinance.Domain.Category @{     ViewBag.Title = "Create Category"; }   <div data-role="page"> <div data-role="header">      <h1>Create Category</h1>             @Html.ActionLink("Home", "Index","Home",null, new { @class = "ui-btn-right" })      </div>       <div data-role="content">     @using (Html.BeginForm("Create","Category",FormMethod.Post))     {       <div data-role="fieldcontain">        @Html.LabelFor(model => model.Name)        @Html.EditorFor(model => model.Name)        <div>           @Html.ValidationMessageFor(m => m.Name)        </div>         </div>         <div data-role="fieldcontain">         @Html.LabelFor(model => model.Description)         @Html.EditorFor(model => model.Description)                   </div>                    <div class="ui-body ui-body-b">         <button type="submit" data-role="button" data-theme="b">Save</button>       </div>     }        </div> </div>   In jQuery Mobile, the form elements should be placed inside the data-role="fieldcontain" The below screen shots show the pages rendered in mobile browser Index Page Create Page Source Code You can download the source code from http://efmvc.codeplex.com   Summary We have created a single  web app for desktop browsers and mobile browsers. If a user access the site from desktop browsers, users will get normal web pages and get mobile specific pages if users access from mobile browsers. If users are accessing the website from mobile devices, we will redirect to a ASP.NET MVC area Mobile. For redirecting to the Mobile area, we have used a Global filer for the redirection logic and used open source framework 51Degrees.mobi for the better support for mobile browser detection. In the Mobile area, we have created the pages using jQuery Mobile and users will get mobile friendly web pages. We can create great mobile web apps using ASP.NET MVC  and jQuery Mobile Framework.

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  • Metro, Authentication, and the ASP.NET Web API

    - by Stephen.Walther
    Imagine that you want to create a Metro style app written with JavaScript and you want to communicate with a remote web service. For example, you are creating a movie app which retrieves a list of movies from a movies service. In this situation, how do you authenticate your Metro app and the Metro user so not just anyone can call the movies service? How can you identify the user making the request so you can return user specific data from the service? The Windows Live SDK supports a feature named Single Sign-On. When a user logs into a Windows 8 machine using their Live ID, you can authenticate the user’s identity automatically. Even better, when the Metro app performs a call to a remote web service, you can pass an authentication token to the remote service and prevent unauthorized access to the service. The documentation for Single Sign-On is located here: http://msdn.microsoft.com/en-us/library/live/hh826544.aspx In this blog entry, I describe the steps that you need to follow to use Single Sign-On with a (very) simple movie app. We build a Metro app which communicates with a web service created using the ASP.NET Web API. Creating the Visual Studio Solution Let’s start by creating a Visual Studio solution which contains two projects: a Windows Metro style Blank App project and an ASP.NET MVC 4 Web Application project. Name the Metro app MovieApp and the ASP.NET MVC application MovieApp.Services. When you create the ASP.NET MVC application, select the Web API template: After you create the two projects, your Visual Studio Solution Explorer window should look like this: Configuring the Live SDK You need to get your hands on the Live SDK and register your Metro app. You can download the latest version of the SDK (version 5.2) from the following address: http://www.microsoft.com/en-us/download/details.aspx?id=29938 After you download the Live SDK, you need to visit the following website to register your Metro app: https://manage.dev.live.com/build Don’t let the title of the website — Windows Push Notifications & Live Connect – confuse you, this is the right place. Follow the instructions at the website to register your Metro app. Don’t forget to follow the instructions in Step 3 for updating the information in your Metro app’s manifest. After you register, your client secret is displayed. Record this client secret because you will need it later (we use it with the web service): You need to configure one more thing. You must enter your Redirect Domain by visiting the following website: https://manage.dev.live.com/Applications/Index Click on your application name, click Edit Settings, click the API Settings tab, and enter a value for the Redirect Domain field. You can enter any domain that you please just as long as the domain has not already been taken: For the Redirect Domain, I entered http://superexpertmovieapp.com. Create the Metro MovieApp Next, we need to create the MovieApp. The MovieApp will: 1. Use Single Sign-On to log the current user into Live 2. Call the MoviesService web service 3. Display the results in a ListView control Because we use the Live SDK in the MovieApp, we need to add a reference to it. Right-click your References folder in the Solution Explorer window and add the reference: Here’s the HTML page for the Metro App: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>MovieApp</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.1.0.RC/css/ui-dark.css" rel="stylesheet" /> <script src="//Microsoft.WinJS.1.0.RC/js/base.js"></script> <script src="//Microsoft.WinJS.1.0.RC/js/ui.js"></script> <!-- Live SDK --> <script type="text/javascript" src="/LiveSDKHTML/js/wl.js"></script> <!-- WebServices references --> <link href="/css/default.css" rel="stylesheet" /> <script src="/js/default.js"></script> </head> <body> <div id="tmplMovie" data-win-control="WinJS.Binding.Template"> <div class="movieItem"> <span data-win-bind="innerText:title"></span> <br /><span data-win-bind="innerText:director"></span> </div> </div> <div id="lvMovies" data-win-control="WinJS.UI.ListView" data-win-options="{ itemTemplate: select('#tmplMovie') }"> </div> </body> </html> The HTML page above contains a Template and ListView control. These controls are used to display the movies when the movies are returned from the movies service. Notice that the page includes a reference to the Live script that we registered earlier: <!-- Live SDK --> <script type="text/javascript" src="/LiveSDKHTML/js/wl.js"></script> The JavaScript code looks like this: (function () { "use strict"; var REDIRECT_DOMAIN = "http://superexpertmovieapp.com"; var WEBSERVICE_URL = "http://localhost:49743/api/movies"; function init() { WinJS.UI.processAll().done(function () { // Get element and control references var lvMovies = document.getElementById("lvMovies").winControl; // Login to Windows Live var scopes = ["wl.signin"]; WL.init({ scope: scopes, redirect_uri: REDIRECT_DOMAIN }); WL.login().then( function(response) { // Get the authentication token var authenticationToken = response.session.authentication_token; // Call the web service var options = { url: WEBSERVICE_URL, headers: { authenticationToken: authenticationToken } }; WinJS.xhr(options).done( function (xhr) { var movies = JSON.parse(xhr.response); var listMovies = new WinJS.Binding.List(movies); lvMovies.itemDataSource = listMovies.dataSource; }, function (xhr) { console.log(xhr.statusText); } ); }, function(response) { throw WinJS.ErrorFromName("Failed to login!"); } ); }); } document.addEventListener("DOMContentLoaded", init); })(); There are two constants which you need to set to get the code above to work: REDIRECT_DOMAIN and WEBSERVICE_URL. The REDIRECT_DOMAIN is the domain that you entered when registering your app with Live. The WEBSERVICE_URL is the path to your web service. You can get the correct value for WEBSERVICE_URL by opening the Project Properties for the MovieApp.Services project, clicking the Web tab, and getting the correct URL. The port number is randomly generated. In my code, I used the URL  “http://localhost:49743/api/movies”. Assuming that the user is logged into Windows 8 with a Live account, when the user runs the MovieApp, the user is logged into Live automatically. The user is logged in with the following code: // Login to Windows Live var scopes = ["wl.signin"]; WL.init({ scope: scopes, redirect_uri: REDIRECT_DOMAIN }); WL.login().then(function(response) { // Do something }); The scopes setting determines what the user has permission to do. For example, access the user’s SkyDrive or access the user’s calendar or contacts. The available scopes are listed here: http://msdn.microsoft.com/en-us/library/live/hh243646.aspx In our case, we only need the wl.signin scope which enables Single Sign-On. After the user signs in, you can retrieve the user’s Live authentication token. The authentication token is passed to the movies service to authenticate the user. Creating the Movies Service The Movies Service is implemented as an API controller in an ASP.NET MVC 4 Web API project. Here’s what the MoviesController looks like: using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using JWTSample; using MovieApp.Services.Models; namespace MovieApp.Services.Controllers { public class MoviesController : ApiController { const string CLIENT_SECRET = "NtxjF2wu7JeY1unvVN-lb0hoeWOMUFoR"; // GET api/values public HttpResponseMessage Get() { // Authenticate // Get authenticationToken var authenticationToken = Request.Headers.GetValues("authenticationToken").FirstOrDefault(); if (authenticationToken == null) { return new HttpResponseMessage(HttpStatusCode.Unauthorized); } // Validate token var d = new Dictionary<int, string>(); d.Add(0, CLIENT_SECRET); try { var myJWT = new JsonWebToken(authenticationToken, d); } catch { return new HttpResponseMessage(HttpStatusCode.Unauthorized); } // Return results return Request.CreateResponse( HttpStatusCode.OK, new List<Movie> { new Movie {Title="Star Wars", Director="Lucas"}, new Movie {Title="King Kong", Director="Jackson"}, new Movie {Title="Memento", Director="Nolan"} } ); } } } Because the Metro app performs an HTTP GET request, the MovieController Get() action is invoked. This action returns a set of three movies when, and only when, the authentication token is validated. The Movie class looks like this: using Newtonsoft.Json; namespace MovieApp.Services.Models { public class Movie { [JsonProperty(PropertyName="title")] public string Title { get; set; } [JsonProperty(PropertyName="director")] public string Director { get; set; } } } Notice that the Movie class uses the JsonProperty attribute to change Title to title and Director to director to make JavaScript developers happy. The Get() method validates the authentication token before returning the movies to the Metro app. To get authentication to work, you need to provide the client secret which you created at the Live management site. If you forgot to write down the secret, you can get it again here: https://manage.dev.live.com/Applications/Index The client secret is assigned to a constant at the top of the MoviesController class. The MoviesController class uses a helper class named JsonWebToken to validate the authentication token. This class was created by the Windows Live team. You can get the source code for the JsonWebToken class from the following GitHub repository: https://github.com/liveservices/LiveSDK/blob/master/Samples/Asp.net/AuthenticationTokenSample/JsonWebToken.cs You need to add an additional reference to your MVC project to use the JsonWebToken class: System.Runtime.Serialization. You can use the JsonWebToken class to get a unique and validated user ID like this: var user = myJWT.Claims.UserId; If you need to store user specific information then you can use the UserId property to uniquely identify the user making the web service call. Running the MovieApp When you first run the Metro MovieApp, you get a screen which asks whether the app should have permission to use Single Sign-On. This screen never appears again after you give permission once. Actually, when I first ran the app, I get the following error: According to the error, the app is blocked because “We detected some suspicious activity with your Online Id account. To help protect you, we’ve temporarily blocked your account.” This appears to be a bug in the current preview release of the Live SDK and there is more information about this bug here: http://social.msdn.microsoft.com/Forums/en-US/messengerconnect/thread/866c495f-2127-429d-ab07-842ef84f16ae/ If you click continue, and continue running the app, the error message does not appear again.  Summary The goal of this blog entry was to describe how you can validate Metro apps and Metro users when performing a call to a remote web service. First, I explained how you can create a Metro app which takes advantage of Single Sign-On to authenticate the current user against Live automatically. You learned how to register your Metro app with Live and how to include an authentication token in an Ajax call. Next, I explained how you can validate the authentication token – retrieved from the request header – in a web service. I discussed how you can use the JsonWebToken class to validate the authentication token and retrieve the unique user ID.

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  • Using VLOOKUP in Excel

    - by Mark Virtue
    VLOOKUP is one of Excel’s most useful functions, and it’s also one of the least understood.  In this article, we demystify VLOOKUP by way of a real-life example.  We’ll create a usable Invoice Template for a fictitious company. So what is VLOOKUP?  Well, of course it’s an Excel function.  This article will assume that the reader already has a passing understanding of Excel functions, and can use basic functions such as SUM, AVERAGE, and TODAY.  In its most common usage, VLOOKUP is a database function, meaning that it works with database tables – or more simply, lists of things in an Excel worksheet.  What sort of things?   Well, any sort of thing.  You may have a worksheet that contains a list of employees, or products, or customers, or CDs in your CD collection, or stars in the night sky.  It doesn’t really matter. Here’s an example of a list, or database.  In this case it’s a list of products that our fictitious company sells: Usually lists like this have some sort of unique identifier for each item in the list.  In this case, the unique identifier is in the “Item Code” column.  Note:  For the VLOOKUP function to work with a database/list, that list must have a column containing the unique identifier (or “key”, or “ID”), and that column must be the first column in the table.  Our sample database above satisfies this criterion. The hardest part of using VLOOKUP is understanding exactly what it’s for.  So let’s see if we can get that clear first: VLOOKUP retrieves information from a database/list based on a supplied instance of the unique identifier. Put another way, if you put the VLOOKUP function into a cell and pass it one of the unique identifiers from your database, it will return you one of the pieces of information associated with that unique identifier.  In the example above, you would pass VLOOKUP an item code, and it would return to you either the corresponding item’s description, its price, or its availability (its “In stock” quantity).  Which of these pieces of information will it pass you back?  Well, you get to decide this when you’re creating the formula. If all you need is one piece of information from the database, it would be a lot of trouble to go to to construct a formula with a VLOOKUP function in it.  Typically you would use this sort of functionality in a reusable spreadsheet, such as a template.  Each time someone enters a valid item code, the system would retrieve all the necessary information about the corresponding item. Let’s create an example of this:  An Invoice Template that we can reuse over and over in our fictitious company. First we start Excel… …and we create ourselves a blank invoice: This is how it’s going to work:  The person using the invoice template will fill in a series of item codes in column “A”, and the system will retrieve each item’s description and price, which will be used to calculate the line total for each item (assuming we enter a valid quantity). For the purposes of keeping this example simple, we will locate the product database on a separate sheet in the same workbook: In reality, it’s more likely that the product database would be located in a separate workbook.  It makes little difference to the VLOOKUP function, which doesn’t really care if the database is located on the same sheet, a different sheet, or a completely different workbook. In order to test the VLOOKUP formula we’re about to write, we first enter a valid item code into cell A11: Next, we move the active cell to the cell in which we want information retrieved from the database by VLOOKUP to be stored.  Interestingly, this is the step that most people get wrong.  To explain further:  We are about to create a VLOOKUP formula that will retrieve the description that corresponds to the item code in cell A11.  Where do we want this description put when we get it?  In cell B11, of course.  So that’s where we write the VLOOKUP formula – in cell B11. Select cell B11: We need to locate the list of all available functions that Excel has to offer, so that we can choose VLOOKUP and get some assistance in completing the formula.  This is found by first clicking the Formulas tab, and then clicking Insert Function:   A box appears that allows us to select any of the functions available in Excel.  To find the one we’re looking for, we could type a search term like “lookup” (because the function we’re interested in is a lookup function).  The system would return us a list of all lookup-related functions in Excel.  VLOOKUP is the second one in the list.  Select it an click OK… The Function Arguments box appears, prompting us for all the arguments (or parameters) needed in order to complete the VLOOKUP function.  You can think of this box as the function is asking us the following questions: What unique identifier are you looking up in the database? Where is the database? Which piece of information from the database, associated with the unique identifier, do you wish to have retrieved for you? The first three arguments are shown in bold, indicating that they are mandatory arguments (the VLOOKUP function is incomplete without them and will not return a valid value).  The fourth argument is not bold, meaning that it’s optional:   We will complete the arguments in order, top to bottom. The first argument we need to complete is the Lookup_value argument.  The function needs us to tell it where to find the unique identifier (the item code in this case) that it should be retuning the description of.  We must select the item code we entered earlier (in A11). Click on the selector icon to the right of the first argument: Then click once on the cell containing the item code (A11), and press Enter: The value of “A11” is inserted into the first argument. Now we need to enter a value for the Table_array argument.  In other words, we need to tell VLOOKUP where to find the database/list.  Click on the selector icon next to the second argument: Now locate the database/list and select the entire list – not including the header line.  The database is located on a separate worksheet, so we first click on that worksheet tab: Next we select the entire database, not including the header line: …and press Enter.  The range of cells that represents the database (in this case “’Product Database’!A2:D7”) is entered automatically for us into the second argument. Now we need to enter the third argument, Col_index_num.  We use this argument to specify to VLOOKUP which piece of information from the database, associate with our item code in A11, we wish to have returned to us.  In this particular example, we wish to have the item’s description returned to us.  If you look on the database worksheet, you’ll notice that the “Description” column is the second column in the database.  This means that we must enter a value of “2” into the Col_index_num box: It is important to note that that we are not entering a “2” here because the “Description” column is in the B column on that worksheet.  If the database happened to start in column K of the worksheet, we would still enter a “2” in this field. Finally, we need to decide whether to enter a value into the final VLOOKUP argument, Range_lookup.  This argument requires either a true or false value, or it should be left blank.  When using VLOOKUP with databases (as is true 90% of the time), then the way to decide what to put in this argument can be thought of as follows: If the first column of the database (the column that contains the unique identifiers) is sorted alphabetically/numerically in ascending order, then it’s possible to enter a value of true into this argument, or leave it blank. If the first column of the database is not sorted, or it’s sorted in descending order, then you must enter a value of false into this argument As the first column of our database is not sorted, we enter false into this argument: That’s it!  We’ve entered all the information required for VLOOKUP to return the value we need.  Click the OK button and notice that the description corresponding to item code “R99245” has been correctly entered into cell B11: The formula that was created for us looks like this: If we enter a different item code into cell A11, we will begin to see the power of the VLOOKUP function:  The description cell changes to match the new item code: We can perform a similar set of steps to get the item’s price returned into cell E11.  Note that the new formula must be created in cell E11.  The result will look like this: …and the formula will look like this: Note that the only difference between the two formulae is the third argument (Col_index_num) has changed from a “2” to a “3” (because we want data retrieved from the 3rd column in the database). If we decided to buy 2 of these items, we would enter a “2” into cell D11.  We would then enter a simple formula into cell F11 to get the line total: =D11*E11 …which looks like this… Completing the Invoice Template We’ve learned a lot about VLOOKUP so far.  In fact, we’ve learned all we’re going to learn in this article.  It’s important to note that VLOOKUP can be used in other circumstances besides databases.  This is less common, and may be covered in future How-To Geek articles. Our invoice template is not yet complete.  In order to complete it, we would do the following: We would remove the sample item code from cell A11 and the “2” from cell D11.  This will cause our newly created VLOOKUP formulae to display error messages: We can remedy this by judicious use of Excel’s IF() and ISBLANK() functions.  We change our formula from this…       =VLOOKUP(A11,’Product Database’!A2:D7,2,FALSE) …to this…       =IF(ISBLANK(A11),”",VLOOKUP(A11,’Product Database’!A2:D7,2,FALSE)) We would copy the formulas in cells B11, E11 and F11 down to the remainder of the item rows of the invoice.  Note that if we do this, the resulting formulas will no longer correctly refer to the database table.  We could fix this by changing the cell references for the database to absolute cell references.  Alternatively – and even better – we could create a range name for the entire product database (such as “Products”), and use this range name instead of the cell references.  The formula would change from this…       =IF(ISBLANK(A11),”",VLOOKUP(A11,’Product Database’!A2:D7,2,FALSE)) …to this…       =IF(ISBLANK(A11),”",VLOOKUP(A11,Products,2,FALSE)) …and then copy the formulas down to the rest of the invoice item rows. We would probably “lock” the cells that contain our formulae (or rather unlock the other cells), and then protect the worksheet, in order to ensure that our carefully constructed formulae are not accidentally overwritten when someone comes to fill in the invoice. We would save the file as a template, so that it could be reused by everyone in our company If we were feeling really clever, we would create a database of all our customers in another worksheet, and then use the customer ID entered in cell F5 to automatically fill in the customer’s name and address in cells B6, B7 and B8. If you would like to practice with VLOOKUP, or simply see our resulting Invoice Template, it can be downloaded from here. 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