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  • Dependency injection: At what point am I allowed to create a new object?

    - by Gaz_Edge
    I am refactoring a PHP application, and I am trying to do has much dependency injection (DI) as possible. I feel like I've got a good grasp of how it works, and I can certainly see my classes becoming a lot leaner and more robust. I'm refactoring so that I can inject a dependency rather than create a new object within the class, but at some point I am going to have to create some objects, that is, use the dreaded new keyword. The problem I have now run into is at what point can I actually create new objects? It's looking like I'll end up at a top level class, creating loads of new objects as there is no where else to go. This feels wrong. I've read some blogs that use factory classes to create all the objects, and then you inject the factory into other classes. You can then call the factory methods, and the factory creates the new object for you. My concern with doing this is now my factory classes are going to be a new free-for-all! I guess this may be OK as they are factory classes, but are there some rules to stick to when using a factory pattern and DI, or am I going way off the mark here?

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  • A friend told me Python is garbage, I'm taking web design classes in the Spring and I have a textbook on C++. What should I do? [on hold]

    - by user107165
    I dont know if I should start digging into Python beforehand just to get acquanited with programming and "whet my appetite" or if I should work on the C++ book... Python definitely has more resources around town and I like the beginner friendly approach that seems to go along with every site that appeals to it. Or should I just wait for my assignments that start in 4 months? Any tips for an aspiring programmer?

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  • Dependency Injection: What point am I allowed to create a new object?

    - by Gaz_Edge
    I am refactoring a php application and I am trying to do has much dependency injection as possible. I feel like I've got a good grasp of how it works, and I can certainly see my classes becoming a lot leaner and more robust. Im refactoring so that I can inject a dependency rather than create a new object within the class, but at some point I am going to have to create some objects i.e. use the dreaded new keyword. The problem I have now run into is at what point can I actually create new objects? Its looking like I'll end up at a top level class, creating loads of new objects as there is no where else to go. This feels wrong. I've read some blogs that use factory classes to create all the objects, and then you inject the factory into other classes. You can then call the factory methods, and the factory creates the new object for you. My concern with doing this is now my factory classes are going to be a new free-for-all! I guess this may be ok as they are factory classes, but are there some rules to stick to when using factory pattern and DI, or am I going way off the mark here.

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  • Break a class in twain, or impose an interface for restricted access?

    - by bedwyr
    What's the best way of partitioning a class when its functionality needs to be externally accessed in different ways by different classes? Hopefully the following example will make the question clear :) I have a Java class which accesses a single location in a directory allowing external classes to perform read/write operations to it. Read operations return usage stats on the directory (e.g. available disk space, number of writes, etc.); write operations, obviously, allow external classes to write data to the disk. These methods always work on the same location, and receive their configuration (e.g. which directory to use, min disk space, etc.) from an external source (passed to the constructor). This class looks something like this: public class DiskHandler { public DiskHandler(String dir, int minSpace) { ... } public void writeToDisk(String contents, String filename) { int space = getAvailableSpace(); ... } public void getAvailableSpace() { ... } } There's quite a bit more going on, but this will do to suffice. This class needs to be accessed differently by two external classes. One class needs access to the read operations; the other needs access to both read and write operations. public class DiskWriter { DiskHandler diskHandler; public DiskWriter() { diskHandler = new DiskHandler(...); } public void doSomething() { diskHandler.writeToDisk(...); } } public class DiskReader { DiskHandler diskHandler; public DiskReader() { diskHandler = new DiskHandler(...); } public void doSomething() { int space = diskHandler.getAvailableSpace(...); } } At this point, both classes share the same class, but the class which should only read has access to the write methods. Solution 1 I could break this class into two. One class would handle read operations, and the other would handle writes: // NEW "UTILITY" CLASSES public class WriterUtil { private ReaderUtil diskReader; public WriterUtil(String dir, int minSpace) { ... diskReader = new ReaderUtil(dir, minSpace); } public void writeToDisk(String contents, String filename) { int = diskReader.getAvailableSpace(); ... } } public class ReaderUtil { public ReaderUtil(String dir, int minSpace) { ... } public void getAvailableSpace() { ... } } // MODIFIED EXTERNALLY-ACCESSING CLASSES public class DiskWriter { WriterUtil diskWriter; public DiskWriter() { diskWriter = new WriterUtil(...); } public void doSomething() { diskWriter.writeToDisk(...); } } public class DiskReader { ReaderUtil diskReader; public DiskReader() { diskReader = new ReaderUtil(...); } public void doSomething() { int space = diskReader.getAvailableSpace(...); } } This solution prevents classes from having access to methods they should not, but it also breaks encapsulation. The original DiskHandler class was completely self-contained and only needed config parameters via a single constructor. By breaking apart the functionality into read/write classes, they both are concerned with the directory and both need to be instantiated with their respective values. In essence, I don't really care to duplicate the concerns. Solution 2 I could implement an interface which only provisions read operations, and use this when a class only needs access to those methods. The interface might look something like this: public interface Readable { int getAvailableSpace(); } The Reader class would instantiate the object like this: Readable diskReader; public DiskReader() { diskReader = new DiskHandler(...); } This solution seems brittle, and prone to confusion in the future. It doesn't guarantee developers will use the correct interface in the future. Any changes to the implementation of the DiskHandler could also need to update the interface as well as the accessing classes. I like it better than the previous solution, but not by much. Frankly, neither of these solutions seems perfect, but I'm not sure if one should be preferred over the other. I really don't want to break the original class up, but I also don't know if the interface buys me much in the long run. Are there other solutions I'm missing?

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  • How to register a domain for a beginner?

    - by garbage collection
    I've never registered a .com , .net like domain before, and I would like to do some research before doing so. I currently have a ruby on rails app running Heroku. Is there anything special I have to do prior to registering domain on my ruby on rails app at all? Or is it as easy as just inserting my current Heroku address to mask it with another .com or .net name? Is there some special features I should look for registering domain? Or is it typical for domain seller to just sell domain names only? Any recommendations on sellers? Thank you.

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  • How to resolve java.nio.charset.UnmappableCharacterException in Scala 2.8.0?

    - by Roman Kagan
    I'm using Scala 2.8.0 and trying to read pipe delimited file like in code snipped below: object Main { def main(args: Array[String]) :Unit = { if (args.length > 0) { val lines = scala.io.Source.fromPath("QUICK!LRU-2009-11-15.psv") for (line <-lines) print(line) } } } Here's the error: Exception in thread "main" java.nio.charset.UnmappableCharacterException: Input length = 1 at java.nio.charset.CoderResult.throwException(CoderResult.java:261) at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:319) at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:158) at java.io.InputStreamReader.read(InputStreamReader.java:167) at java.io.BufferedReader.fill(BufferedReader.java:136) at java.io.BufferedReader.read(BufferedReader.java:157) at scala.io.BufferedSource$$anonfun$1$$anonfun$apply$1.apply(BufferedSource.scala:29) at scala.io.BufferedSource$$anonfun$1$$anonfun$apply$1.apply(BufferedSource.scala:29) at scala.io.Codec.wrap(Codec.scala:65) at scala.io.BufferedSource$$anonfun$1.apply(BufferedSource.scala:29) at scala.io.BufferedSource$$anonfun$1.apply(BufferedSource.scala:29) at scala.collection.Iterator$$anon$14.next(Iterator.scala:149) at scala.collection.Iterator$$anon$2.next(Iterator.scala:745) at scala.collection.Iterator$$anon$2.head(Iterator.scala:732) at scala.collection.Iterator$$anon$24.hasNext(Iterator.scala:405) at scala.collection.Iterator$$anon$20.hasNext(Iterator.scala:320) at scala.io.Source.hasNext(Source.scala:209) at scala.collection.Iterator$class.foreach(Iterator.scala:534) at scala.io.Source.foreach(Source.scala:143) ... at infillreports.Main$.main(Main.scala:8) at infillreports.Main.main(Main.scala) Java Result: 1

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  • Swift Mailer email sending problem

    - by air
    i have downloaded Swift Mailer from their website and try to send simple email with following code <?php require_once 'lib/swift_required.php'; $transport = Swift_SmtpTransport::newInstance('smtp.example.org', 25) ->setUsername('your username') ->setPassword('your password') ; $mailer = Swift_Mailer::newInstance($transport); //Create a message $message = Swift_Message::newInstance('Wonderful Subject') ->setFrom(array('[email protected]' => 'John Doe')) ->setTo(array('[email protected]', '[email protected]' => 'A name')) ->setBody('Here is the message itself') ; //Send the message $result = $mailer->send($message); ? once i run the page it gives error Warning: fsockopen() [function.fsockopen]: php_network_getaddresses: getaddrinfo failed: No such host is known. in E:\web_sites\swift_mail\lib\classes\Swift\Transport\StreamBuffer.php on line 233 Warning: fsockopen() [function.fsockopen]: unable to connect to smtp.fiveocean.net:25 (php_network_getaddresses: getaddrinfo failed: No such host is known. ) in E:\web_sites\swift_mail\lib\classes\Swift\Transport\StreamBuffer.php on line 233 Fatal error: Uncaught exception 'Swift_TransportException' with message 'Connection could not be established with host smtp.fiveocean.net [php_network_getaddresses: getaddrinfo failed: No such host is known. #0]' in E:\web_sites\swift_mail\lib\classes\Swift\Transport\StreamBuffer.php:235 Stack trace: #0 E:\web_sites\swift_mail\lib\classes\Swift\Transport\StreamBuffer.php(70): Swift_Transport_StreamBuffer->_establishSocketConnection() #1 E:\web_sites\swift_mail\lib\classes\Swift\Transport\AbstractSmtpTransport.php(101): Swift_Transport_StreamBuffer->initialize(Array) #2 E:\web_sites\swift_mail\lib\classes\Swift\Mailer.php(74): Swift_Transport_AbstractSmtpTransport->start() #3 E:\web_sites\swift_mail\test.php(33): Swift_Mailer->send(Object(Swift_Message)) #4 {main} thrown in E:\web_sites\swift_mail\lib\classes\Swift\Transport\StreamBuffer.php on line 235 if i remove the line $result = $mailer->send($message); then page execute and no error message display, as soon as i add above line to send email, i got error. my outgoing server, port and user id & passwords are correct in my file. Thanks

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  • load class not in classpath dynamically in web application - without using custom classloader

    - by swdeveloper
    I am developing a web application. The web application generates java classes on the fly. For example it generates class com.people.Customer.java In my code, I dynamically compile this to get com.people.Customer.class and store in some directory say repository/com/people/Customer.class which is not on the classpath of my application server.My application server(I am using WebSphere Application Server/Apache Tomcat etc) picks up the classes from the WEB-INF/classes directory. The Classloader would use this to load the classes. After compilation I need to load this class so that it becomes accessible to other classes using it after its creation. 4.When I use Thread.currentThread().getContextClassLoader().loadClass(com.people.Customer) obviously the Classloader is not able to load the class, since its not on the classpath(not in WEB-INF/classes). Due to similar reasons, getResource(..) or getResourceAsStream(..) also does not work. I need a way to : Read the class Customer.class maybe as a stream (or any other way would do) and then load it. Following are the constraints: I cannot add the repository folder to the WEB-INF/classes folder. I cannot create a new Custom ClassLoader. If I create a new ClassLoader and this loads the class, it will not be accessible to its parent ClassLoader. Is there any way of achieving this? If not this, in the worse case, is there a way of overriding the default class loader with a custom class loader for web applications the same classloader should be used to load applications throughout entire lifecycle of my web application. Appreciate any solution :)

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  • OData / WCF Data Service - HTTP 500 Error

    - by Eric
    I have created an OData/WCF service using Visual Studio 2010 on Windows XP SP3 with all current patches installed. When I click on "view in browser", the service opens and I see the 3 tables from my EF model. However, when I add a table name ("Commands" in this case) to the end of the query string, rather than seeing the data from the table, I get an HTTP 500 error. (This error (HTTP 500 Internal Server Error) means that the website you are visiting had a server problem which prevented the webpage from displaying.). I have not only followed the examples from 2 sites, but have also tried running the sample application that the blog poster sent me (that works on his machine), and still am not having any luck. The blog post is at Exposing OData from an Entity Framework Model Does anyone have an idea why this is occurring and how to resolve it? Here is the output of the "View in Browser": <?xml version="1.0" encoding="utf-8" standalone="yes" ?> - <service xml:base="http://localhost:1883/VistaDBCommandService.svc/" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:app="http://www.w3.org/2007/app" xmlns="http://www.w3.org/2007/app"> - <workspace> <atom:title>Default</atom:title> - <collection href="Commands"> <atom:title>Commands</atom:title> </collection> - <collection href="Databases"> <atom:title>Databases</atom:title> </collection> - <collection href="Statuses"> <atom:title>Statuses</atom:title> </collection> </workspace> </service> ============================= Thanks, Eric

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  • Need advice on OOP philosophy

    - by David Jenings
    I'm trying to get the wheels turning on a large project in C#. My previous experience is in Delphi, where by default every form was created at applicaton startup and form references where held in (gasp) global variables. So I'm trying to adapt my thinking to a 100% object oriented environment, and my head is spinning just a little. My app will have a large collection of classes Most of these classes will only really need one instance. So I was thinking: static classes. I'm not really sure why, but much of what I've read here says that if my class is going to hold a state, which I take to mean any property values at all, I should use a singleton structure instead. Okay. But there are people out there who for reasons that escape me, think that singletons are evil too. None of these classes is in danger of being used anywhere except in this program. So they could certainly work fine as regular objects (vs singletons or static classes) Then there's the issue of interaction between objects. I'm tempted to create a Global class full of public static properties referencing the single instances of many of these classes. I've also considered just making them properties (static or instance, not sure which) of the MainForm. Then I'd have each of my classes be aware of the MainForm as Owner. Then the various objects could refer to each other as Owner.Object1, Owner.Object2, etc. I fear I'm running out of electronic ink, or at least taxing the patience of anyone kind enough to have stuck with me this long. I hope I have clearly explained my state of utter confusion. I'm just looking for some advice on best practices in my situation. All input is welcome and appreciated. Thanks in advance, David Jennings

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  • jquery: Writing a method

    - by Mark
    This is the same question as this: http://stackoverflow.com/questions/2890620/jquery-running-a-function-in-a-context-and-adding-to-a-variable But that question was poorly posed. Trying again, I'm trying to do something like this: I have a bunch of elements I want to grab data from, the data is in the form of classes of the element children. <div id='container'> <span class='a'></span> <span class='b'></span> <span class='c'></span> </div> <div id='container2'> <span class='1'></span> <span class='2'></span> <span class='3'></span> </div> I have a method like this: jQuery.fn.grabData = function(expr) { return this.each(function() { var self = $(this); self.find("span").each(function (){ var info = $(this).attr('class'); collection += info; }); }); }; I to run the method like this: var collection = ''; $('#container').grabData(); $('#container2').grabData(); The collection should be adding to each other so that in the end I get this console.log(collection); : abc123 But collection is undefined in the method. How can I let the method know which collection it should be adding to? Thanks.

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  • Lucene raise document score if sibling entity matches query

    - by Pitagoras
    I have the following design situation. I use hibernate search (lucene in the back). Tha application manages ITEMs which have title, description and tags. These are full text indexed. On the other hand, we have COLLECTION of ITEMs. The user can create a COLLECTION and add as many ITEMs as she wants. ITEMs can also belong to many COLLECTIONs. I have a boosted query so that search terms that appear in the tags are more important than in the title, and lastly in the description. But I need an additional matching criteria: for a given ITEM, it whould rank better if other documents in some COLLECTION where the ITEM belongs, also match the query. This is like to say: the title/tags/description of "fellow" items (i.e. items in some shared collection) make the item rank better. I was thinking that adding an ITEM to a COLLECTION would add something like "extra tags" to every other ITEM in the collection, being these extra tags the elements to match in the added ITEM. I feel a more clever solution lucene-wise should exists. Any ideas/pointers are welcome. Thanks.

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  • Permuting output of a tree of closures

    - by yan
    This a conceptual question on how one would implement the following in Lisp (assuming Common Lisp in my case, but any dialect would work). Assume you have a function that creates closures that sequentially iterate over an arbitrary collection (or otherwise return different values) of data and returns nil when exhausted, i.e. (defun make-counter (up-to) (let ((cnt 0)) (lambda () (if (< cnt up-to) (incf cnt) nil)))) CL-USER> (defvar gen (make-counter 3)) GEN CL-USER> (funcall gen) 1 CL-USER> (funcall gen) 2 CL-USER> (funcall gen) 3 CL-USER> (funcall gen) NIL CL-USER> (funcall gen) NIL Now, assume you are trying to permute a combinations of one or more of these closures. How would you implement a function that returns a new closure that subsequently creates a permutation of all closures contained within it? i.e.: (defun permute-closures (counters) ......) such that the following holds true: CL-USER> (defvar collection (permute-closures (list (make-counter 3) (make-counter 3)))) CL-USER> (funcall collection) (1 1) CL-USER> (funcall collection) (1 2) CL-USER> (funcall collection) (1 3) CL-USER> (funcall collection) (2 1) ... and so on. The way I had it designed originally was to add a 'pause' parameter to the initial counting lambda such that when iterating you can still call it and receive the old cached value if passed ":pause t", in hopes of making the permutation slightly cleaner. Also, while the example above is a simple list of two identical closures, the list can be an arbitrarily-complicated tree (which can be permuted in depth-first order, and the resulting permutation set would have the shape of the tree.). I had this implemented, but my solution wasn't very clean and am trying to poll how others would approach the problem. Thanks in advance.

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  • Cannot serialize this List<T> extension

    - by Jaxidian
    I'm trying to push a subset of a collection of data through WCF to be consumed by WCF - think paged data. As such, I want this collection to have one page's worth of data as well as a total number of results. I figured this should be trivial by creating a custom object that extends List. However, everything I do results in my TotalNumber property coming across as 0. All of the data gets serialized/deserialized just fine but that single integer won't come across at all. Here's my first attempt that failed: [Serializable] public class PartialList<T> : List<T> { public PartialList() { } public PartialList(IEnumerable<T> collection) : base(collection) { } [DataMember] public int UnpartialTotalCount { get; set; } And here's my second attempt that failed in the exact same way: [Serializable] public class PartialList<T> : List<T>, ISerializable { public PartialList() { } public PartialList(IEnumerable<T> collection) : base(collection) { } [DataMember] public int UnpartialTotalCount { get; set; } protected PartialList(SerializationInfo info, StreamingContext context) { UnpartialTotalCount = info.GetInt32("UnpartialTotalCount"); } public void GetObjectData(SerializationInfo info, StreamingContext context) { info.AddValue("UnpartialTotalCount", UnpartialTotalCount); } } What's the deal here??

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  • C++ traits question

    - by duli
    I have a templated class template <typename Data> class C { ..... } In most situations, I depend on the compiler to let me substitute types for Data. I call methods foo(), goo() on objects of type Data, so what I substitute needs to provide that. I now need to substitute int and string for my Data type. I do not want to specialize because the class is already too big and would require specializing each method (with only small code change). My options (please tell me if there are more) 1) I can provide wrapper classes around int and string which implement the methods foo(), goo() etc 2) provide a traits class traits that calls foo() or goo() on objects of classes that provide foo(),goo() (these are my present substitutable classes) and specialize these classes for int and string. Questions 1) what are the relative merits of 1 vs 2? 2) My traits classes will have static methods. Can a traits class have non-static methods as well? I see most traits classes define constants in the STL. 3) Do I make the traits classes global or should I pass them in as a template parameter for class C?

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  • How to debug Infopath2010 using VS2010

    - by ybbest
    In InfoPath 2010 , you can only use VSTO to write code for your form. However , when you try to debug you will see no attach to process option in the VSTO Project. In order to debug your InfoPath form , you have to do the following steps and debug using Visual Studio 2010. However , if you are not using InfoPath form services with SharePoint2010 and only using InfoPath Filler , you can see how to debug here. 1. You need to go to VSTO Project properties >> Build >> Advanced option >> Set the debug info to Full. (As shown below.) 2.Republish your form,this will rebuild your VSTO Project using the new build configurations. 3. Deploy the infopath form from the central admin and activate your form template to a site collection. If you have already deployed the form before , you need to do some clean up steps :     a.Delete all the infopath forms from the form library where you use your infopath form template as a content type     b.Remove the contentType from this form library     c.Deactivate the contype feature from the site collection features.     d.Delete the infopath form template from the central admin     e.Upload the new form template from from the central admin , you need to uncheck Upgrade the form template if it already exists     f.Activate the form template to the site collection and asscociate the contentType with your form library again. If the Above steps does not work , you need to delete the site collection and create a new one. 4. Open the FormCode.cs file you would like to debug in Visual studio 2010(just the file not the whole project),attach the w3wp.exe processes and set a breakpoint in the FormEvents_Loading event. Now if you add a new form to the form liabrary , the breakpoint should be hit.(See screenshot below) As mentioned above , if it does not hit.You might need to delete the site collection and create a new one.Delete the form template and reupload it again remember to uncheck Upgrade the form template if it already exists .Then you should be able to debug your infopath form.I do not see why debugging in InfoPath2010 is so much harder,but here we go.Happy SharePointing and InfoPathing .

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  • SharePoint 2010 Hosting :: How to Enable Office Web Apps on SharePoint 2010

    - by mbridge
    Office Web App is the online version of Microsoft Office 2010 which is very helpful if you are going to use SharePoint 2010 in your organization as it allows you to do basic editing of word document without installing the Office Suite in the client machine. Prerequisites : - Microsoft Server 2008 R2 - Microsoft SharePoint Server 2010 or Microsoft SharePoint Foundation 2010 - Microsoft Office Web Apps. If you have installed all the above products, just follow this steps: 1. Go to Central Administration > Click on Manage Service Application. 2. All the menus are not displayed in ribbon Menu format which was first introduced in Office 2007. Click on New > Word Viewing Services ( You can choose PowerPoint or Excel also, steps are same ). This will open a pop window. Adding Services for Office Web Apps 3. Give a Proper Name which can have your companies or project name. 4. Under Application Pool select : SharePoint Web Services Default. 5. Next keep the check box checked which says : Add this service application’s proxy to the farm’s default proxy list. Click Ok Adding Word Viewer as Service Application Office Web Apps as Services in Sharepoint 2010 6. This will install all the Office Web App services required. You can see the name as you gave in the above step. How to Activate Office Web Apps in Site Collection? 1. Go to the site for which you want to activate this feature. 2. Click on Site Action > Site Settings > Site Collection Administrator > Site Collection Features 3. Activate Office Web Apps. Activate Office Web Apps Feature in Site Collection How to make sure Office Web Apps is working for your site collection? 1. Locate any office document you have and click on the smart menu which appears when you hover your mouse on it. Dont double-click as this will launch the document in Office Client if its installed. This feature can be changed. 2. If you see View or Edit in Browser as menu item, your Office Web Apps is configured correctly. View Edit Office Document in Browser Editing Office Document in Browser Another post related SharePoint 2010: 1. How to Configure SharePoint Foundation 2010 for SharePoint Workspace 2010 2. Integrating SharePoint 2010 and SQL 2008 R2

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  • WPF ListBox not binding to INotifyCollectionChanged or INotifyPropertyChanged Events

    - by Gabe Anzelini
    I have the following test code: private class SomeItem{ public string Title{ get{ return "something"; } } public bool Completed { get { return false; } set { } } } private class SomeCollection : IEnumerable<SomeItem>, INotifyCollectionChanged { private IList<SomeItem> _items = new List<SomeItem>(); public void Add(SomeItem item) { _items.Add(item); CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset)); } #region IEnumerable<SomeItem> Members public IEnumerator<SomeItem> GetEnumerator() { return _items.GetEnumerator(); } #endregion #region IEnumerable Members System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return _items.GetEnumerator(); } #endregion #region INotifyCollectionChanged Members public event NotifyCollectionChangedEventHandler CollectionChanged; #endregion } private SomeCollection collection = new SomeCollection(); private void Expander_Expanded(object sender, RoutedEventArgs e) { var expander = (Expander) sender; var list = expander.DataContext as ITaskList; var listBox = (ListBox)expander.Content; //list.Tasks.CollectionChanged += CollectionChanged; collection.Add(new SomeItem()); collection.Add(new SomeItem()); listBox.ItemsSource = collection; } and the XAML the outer listbox gets populated on load. when the expander gets expanded i then set the itemssource property of the inner listbox (the reason i do this hear instead of using binding is this operation is quite slow and i only want it to take place if the use chooses to view the items). The inner listbox renders fine, but it doesn't actually subscribe to the CollectionChanged event on the collection. I have tried this with ICollection instead of IEnumerable and adding INotifyPropertyChanged as well as replacing INotifyCollectionChanged with INotifyPropertyChanged. The only way I can actually get this to work is to gut my SomeCollection class and inherit from ObservableCollection. My reasoning for trying to role my own INotifyCollectionChanged instead of using ObservableCollection is because I am wrapping a COM collection in the real code. That collection will notify on add/change/remove and I am trying to convert these to INotify events for WPF. Hope this is clear enough (its late).

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  • Silverlight Tree View with Multiple Levels

    - by psheriff
    There are many examples of the Silverlight Tree View that you will find on the web, however, most of them only show you how to go to two levels. What if you have more than two levels? This is where understanding exactly how the Hierarchical Data Templates works is vital. In this blog post, I am going to break down how these templates work so you can really understand what is going on underneath the hood. To start, let’s look at the typical two-level Silverlight Tree View that has been hard coded with the values shown below: <sdk:TreeView>  <sdk:TreeViewItem Header="Managers">    <TextBlock Text="Michael" />    <TextBlock Text="Paul" />  </sdk:TreeViewItem>  <sdk:TreeViewItem Header="Supervisors">    <TextBlock Text="John" />    <TextBlock Text="Tim" />    <TextBlock Text="David" />  </sdk:TreeViewItem></sdk:TreeView> Figure 1 shows you how this tree view looks when you run the Silverlight application. Figure 1: A hard-coded, two level Tree View. Next, let’s create three classes to mimic the hard-coded Tree View shown above. First, you need an Employee class and an EmployeeType class. The Employee class simply has one property called Name. The constructor is created to accept a “name” argument that you can use to set the Name property when you create an Employee object. public class Employee{  public Employee(string name)  {    Name = name;  }   public string Name { get; set; }} Finally you create an EmployeeType class. This class has one property called EmpType and contains a generic List<> collection of Employee objects. The property that holds the collection is called Employees. public class EmployeeType{  public EmployeeType(string empType)  {    EmpType = empType;    Employees = new List<Employee>();  }   public string EmpType { get; set; }  public List<Employee> Employees { get; set; }} Finally we have a collection class called EmployeeTypes created using the generic List<> class. It is in the constructor for this class where you will build the collection of EmployeeTypes and fill it with Employee objects: public class EmployeeTypes : List<EmployeeType>{  public EmployeeTypes()  {    EmployeeType type;            type = new EmployeeType("Manager");    type.Employees.Add(new Employee("Michael"));    type.Employees.Add(new Employee("Paul"));    this.Add(type);     type = new EmployeeType("Project Managers");    type.Employees.Add(new Employee("Tim"));    type.Employees.Add(new Employee("John"));    type.Employees.Add(new Employee("David"));    this.Add(type);  }} You now have a data hierarchy in memory (Figure 2) which is what the Tree View control expects to receive as its data source. Figure 2: A hierachial data structure of Employee Types containing a collection of Employee objects. To connect up this hierarchy of data to your Tree View you create an instance of the EmployeeTypes class in XAML as shown in line 13 of Figure 3. The key assigned to this object is “empTypes”. This key is used as the source of data to the entire Tree View by setting the ItemsSource property as shown in Figure 3, Callout #1. Figure 3: You need to start from the bottom up when laying out your templates for a Tree View. The ItemsSource property of the Tree View control is used as the data source in the Hierarchical Data Template with the key of employeeTypeTemplate. In this case there is only one Hierarchical Data Template, so any data you wish to display within that template comes from the collection of Employee Types. The TextBlock control in line 20 uses the EmpType property of the EmployeeType class. You specify the name of the Hierarchical Data Template to use in the ItemTemplate property of the Tree View (Callout #2). For the second (and last) level of the Tree View control you use a normal <DataTemplate> with the name of employeeTemplate (line 14). The Hierarchical Data Template in lines 17-21 sets its ItemTemplate property to the key name of employeeTemplate (Line 19 connects to Line 14). The source of the data for the <DataTemplate> needs to be a property of the EmployeeTypes collection used in the Hierarchical Data Template. In this case that is the Employees property. In the Employees property there is a “Name” property of the Employee class that is used to display the employee name in the second level of the Tree View (Line 15). What is important here is that your lowest level in your Tree View is expressed in a <DataTemplate> and should be listed first in your Resources section. The next level up in your Tree View should be a <HierarchicalDataTemplate> which has its ItemTemplate property set to the key name of the <DataTemplate> and the ItemsSource property set to the data you wish to display in the <DataTemplate>. The Tree View control should have its ItemsSource property set to the data you wish to display in the <HierarchicalDataTemplate> and its ItemTemplate property set to the key name of the <HierarchicalDataTemplate> object. It is in this way that you get the Tree View to display all levels of your hierarchical data structure. Three Levels in a Tree View Now let’s expand upon this concept and use three levels in our Tree View (Figure 4). This Tree View shows that you now have EmployeeTypes at the top of the tree, followed by a small set of employees that themselves manage employees. This means that the EmployeeType class has a collection of Employee objects. Each Employee class has a collection of Employee objects as well. Figure 4: When using 3 levels in your TreeView you will have 2 Hierarchical Data Templates and 1 Data Template. The EmployeeType class has not changed at all from our previous example. However, the Employee class now has one additional property as shown below: public class Employee{  public Employee(string name)  {    Name = name;    ManagedEmployees = new List<Employee>();  }   public string Name { get; set; }  public List<Employee> ManagedEmployees { get; set; }} The next thing that changes in our code is the EmployeeTypes class. The constructor now needs additional code to create a list of managed employees. Below is the new code. public class EmployeeTypes : List<EmployeeType>{  public EmployeeTypes()  {    EmployeeType type;    Employee emp;    Employee managed;     type = new EmployeeType("Manager");    emp = new Employee("Michael");    managed = new Employee("John");    emp.ManagedEmployees.Add(managed);    managed = new Employee("Tim");    emp.ManagedEmployees.Add(managed);    type.Employees.Add(emp);     emp = new Employee("Paul");    managed = new Employee("Michael");    emp.ManagedEmployees.Add(managed);    managed = new Employee("Sara");    emp.ManagedEmployees.Add(managed);    type.Employees.Add(emp);    this.Add(type);     type = new EmployeeType("Project Managers");    type.Employees.Add(new Employee("Tim"));    type.Employees.Add(new Employee("John"));    type.Employees.Add(new Employee("David"));    this.Add(type);  }} Now that you have all of the data built in your classes, you are now ready to hook up this three-level structure to your Tree View. Figure 5 shows the complete XAML needed to hook up your three-level Tree View. You can see in the XAML that there are now two Hierarchical Data Templates and one Data Template. Again you list the Data Template first since that is the lowest level in your Tree View. The next Hierarchical Data Template listed is the next level up from the lowest level, and finally you have a Hierarchical Data Template for the first level in your tree. You need to work your way from the bottom up when creating your Tree View hierarchy. XAML is processed from the top down, so if you attempt to reference a XAML key name that is below where you are referencing it from, you will get a runtime error. Figure 5: For three levels in a Tree View you will need two Hierarchical Data Templates and one Data Template. Each Hierarchical Data Template uses the previous template as its ItemTemplate. The ItemsSource of each Hierarchical Data Template is used to feed the data to the previous template. This is probably the most confusing part about working with the Tree View control. You are expecting the content of the current Hierarchical Data Template to use the properties set in the ItemsSource property of that template. But you need to look to the template lower down in the XAML to see the source of the data as shown in Figure 6. Figure 6: The properties you use within the Content of a template come from the ItemsSource of the next template in the resources section. Summary Understanding how to put together your hierarchy in a Tree View is simple once you understand that you need to work from the bottom up. Start with the bottom node in your Tree View and determine what that will look like and where the data will come from. You then build the next Hierarchical Data Template to feed the data to the previous template you created. You keep doing this for each level in your Tree View until you get to the last level. The data for that last Hierarchical Data Template comes from the ItemsSource in the Tree View itself. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “Silverlight TreeView with Multiple Levels” from the drop down list.

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  • Using the Data Form Web Part (SharePoint 2010) Site Agnostically!

    - by David Jacobus
    Originally posted on: http://geekswithblogs.net/djacobus/archive/2013/10/24/154465.aspxAs a Developer whom has worked closely with web designers (Power users) in a SharePoint environment, I have come across the issue of making the Data Form Web Part reusable across the site collection! In SharePoint 2007 it was very easy and this blog pointed the way to make it happen: Josh Gaffey's Blog. In SharePoint 2010 something changed! This method failed except for using a Data Form Web Part that pointed to a list in the Site Collection Root! I am making this discussion relative to a developer whom creates a solution (WSP) with all the artifacts embedded and the user shouldn’t have any involvement in the process except to activate features. The Scenario: 1. A Power User creates a Data Form Web Part using SharePoint Designer 2010! It is a great web part the uses all the power of SharePoint Designer and XSLT (Conditional formatting, etc.). 2. Other Users in the site collection want to use that specific web part in sub sites in the site collection. Pointing to a list with the same name, not at the site collection root! The Issues: 1. The Data Form Web Part Data Source uses a List ID (GUID) to point to the specific list. Which means a list in a sub site will have a list with a new GUID different than the one which was created with SharePoint Designer! Obviously, the List needs to be the same List (Fields, Content Types, etc.) with different data. 2. How can we make this web part site agnostic, and dependent only on the lists Name? I had this problem come up over and over and decided to put my solution forward! The Solution: 1. Use the XSL of the Data Form Web Part Created By the Power User in SharePoint Designer! 2. Extend the OOTB Data Form Web Part to use this XSL and Point to a List by name. The solution points to a hybrid solution that requires some coding (Developer) and the XSL (Power User) artifacts put together in a Visual Studio SharePoint Solution. Here are the solution steps in summary: 1. Create an empty SharePoint project in Visual Studio 2. Create a Module and Feature and put the XSL file created by the Power User into it a. Scope the feature to web 3. Create a Feature Receiver to Create the List. The same list from which the Data Form Web Part was created with by the Power User. a. Scope the feature to web 4. Create a Web Part extending the Data Form Web a. Point the Data Form Web Part to point to the List by Name b. Point the Data Form Web Part XSL link to the XSL added using the Module feature c. Scope The feature to Site i. This is because all web parts are in the site collection web part gallery. So in a Narrative Summary: We are creating a list in code which has the same name and (site Columns) as the list from which the Power User created the Data Form Web Part Using SharePoint Designer. We are creating a Web Part in code which extends the OOTB Data Form Web Part to point to a list by name and use the XSL created by the Power User. Okay! Here are the steps with images and code! At the end of this post I will provide a link to the code for a solution which works in any site! I want to TOOT the HORN for the power of this solution! It is the mantra a use with all my clients! What is a basic skill a SharePoint Developer: Create an application that uses the data from a SharePoint list and make that data visible to the user in a manner which meets requirements! Create an Empty SharePoint 2010 Project Here I am naming my Project DJ.DataFormWebPart Create a Code Folder Copy and paste the Extension and Utilities classes (Found in the solution provided at the end of this post) Change the Namespace to match this project The List to which the Data Form Web Part which was used to make the XSL by the Power User in SharePoint Designer is now going to be created in code! If already in code, then all the better! Here I am going to create a list in the site collection root and add some data to it! For the purpose of this discussion I will actually create this list in code before using SharePoint Designer for simplicity! So here I create the List and deploy it within this solution before I do anything else. I will use a List I created before for demo purposes. Footer List is used within the footer of my master page. Add a new Feature: Here I name the Feature FooterList and add a Feature Event Receiver: Here is the code for the Event Receiver: I have a previous blog post about adding lists in code so I will not take time to narrate this code: using System; using System.Runtime.InteropServices; using System.Security.Permissions; using Microsoft.SharePoint; using DJ.DataFormWebPart.Code; namespace DJ.DataFormWebPart.Features.FooterList { /// <summary> /// This class handles events raised during feature activation, deactivation, installation, uninstallation, and upgrade. /// </summary> /// <remarks> /// The GUID attached to this class may be used during packaging and should not be modified. /// </remarks> [Guid("a58644fd-9209-41f4-aa16-67a53af7a9bf")] public class FooterListEventReceiver : SPFeatureReceiver { SPWeb currentWeb = null; SPSite currentSite = null; const string columnGroup = "DJ"; const string ctName = "FooterContentType"; // Uncomment the method below to handle the event raised after a feature has been activated. public override void FeatureActivated(SPFeatureReceiverProperties properties) { using (SPWeb spWeb = properties.GetWeb() as SPWeb) { using (SPSite site = new SPSite(spWeb.Site.ID)) { using (SPWeb rootWeb = site.OpenWeb(site.RootWeb.ID)) { //add the fields addFields(rootWeb); //add content type SPContentType testCT = rootWeb.ContentTypes[ctName]; // we will not create the content type if it exists if (testCT == null) { //the content type does not exist add it addContentType(rootWeb, ctName); } if ((spWeb.Lists.TryGetList("FooterList") == null)) { //create the list if it dosen't to exist CreateFooterList(spWeb, site); } } } } } #region ContentType public void addFields(SPWeb spWeb) { Utilities.addField(spWeb, "Link", SPFieldType.URL, false, columnGroup); Utilities.addField(spWeb, "Information", SPFieldType.Text, false, columnGroup); } private static void addContentType(SPWeb spWeb, string name) { SPContentType myContentType = new SPContentType(spWeb.ContentTypes["Item"], spWeb.ContentTypes, name) { Group = columnGroup }; spWeb.ContentTypes.Add(myContentType); addContentTypeLinkages(spWeb, myContentType); myContentType.Update(); } public static void addContentTypeLinkages(SPWeb spWeb, SPContentType ct) { Utilities.addContentTypeLink(spWeb, "Link", ct); Utilities.addContentTypeLink(spWeb, "Information", ct); } private void CreateFooterList(SPWeb web, SPSite site) { Guid newListGuid = web.Lists.Add("FooterList", "Footer List", SPListTemplateType.GenericList); SPList newList = web.Lists[newListGuid]; newList.ContentTypesEnabled = true; var footer = site.RootWeb.ContentTypes[ctName]; newList.ContentTypes.Add(footer); newList.ContentTypes.Delete(newList.ContentTypes["Item"].Id); newList.Update(); var view = newList.DefaultView; //add all view fields here //view.ViewFields.Add("NewsTitle"); view.ViewFields.Add("Link"); view.ViewFields.Add("Information"); view.Update(); } } } Basically created a content type with two site columns Link and Information. I had to change some code as we are working at the SPWeb level and need Content Types at the SPSite level! I’ll use a new Site Collection for this demo (Best Practice) keep old artifacts from impinging on development: Next we will add this list to the root of the site collection by deploying this solution, add some data and then use SharePoint Designer to create a Data Form Web Part. The list has been added, now let’s add some data: Okay let’s add a Data Form Web Part in SharePoint Designer. Create a new web part page in the site pages library: I will name it TestWP.aspx and edit it in advanced mode: Let’s add an empty Data Form Web Part to the web part zone: Click on the web part to add a data source: Choose FooterList in the Data Source menu: Choose appropriate fields and select insert as multiple item view: Here is what it look like after insertion: Let’s add some conditional formatting if the information filed is not blank: Choose Create (right side) apply formatting: Choose the Information Field and set the condition not null: Click Set Style: Here is the result: Okay! Not flashy but simple enough for this demo. Remember this is the job of the Power user! All we want from this web part is the XLS-Style Sheet out of SharePoint Designer. We are going to use it as the XSL for our web part which we will be creating next. Let’s add a web part to our project extending the OOTB Data Form Web Part. Add new item from the Visual Studio add menu: Choose Web Part: Change WebPart to DataFormWebPart (Oh well my namespace needs some improvement, but it will sure make it readily identifiable as an extended web part!) Below is the code for this web part: using System; using System.ComponentModel; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using Microsoft.SharePoint; using Microsoft.SharePoint.WebControls; using System.Text; namespace DJ.DataFormWebPart.DataFormWebPart { [ToolboxItemAttribute(false)] public class DataFormWebPart : Microsoft.SharePoint.WebPartPages.DataFormWebPart { protected override void OnInit(EventArgs e) { base.OnInit(e); this.ChromeType = PartChromeType.None; this.Title = "FooterListDF"; try { //SPSite site = SPContext.Current.Site; SPWeb web = SPContext.Current.Web; SPList list = web.Lists.TryGetList("FooterList"); if (list != null) { string queryList1 = "<Query><Where><IsNotNull><FieldRef Name='Title' /></IsNotNull></Where><OrderBy><FieldRef Name='Title' Ascending='True' /></OrderBy></Query>"; uint maximumRowList1 = 10; SPDataSource dataSourceList1 = GetDataSource(list.Title, web.Url, list, queryList1, maximumRowList1); this.DataSources.Add(dataSourceList1); this.XslLink = web.Url + "/Assests/Footer.xsl"; this.ParameterBindings = BuildDataFormParameters(); this.DataBind(); } } catch (Exception ex) { this.Controls.Add(new LiteralControl("ERROR: " + ex.Message)); } } private SPDataSource GetDataSource(string dataSourceId, string webUrl, SPList list, string query, uint maximumRow) { SPDataSource dataSource = new SPDataSource(); dataSource.UseInternalName = true; dataSource.ID = dataSourceId; dataSource.DataSourceMode = SPDataSourceMode.List; dataSource.List = list; dataSource.SelectCommand = "" + query + ""; Parameter listIdParam = new Parameter("ListID"); listIdParam.DefaultValue = list.ID.ToString( "B").ToUpper(); Parameter maximumRowsParam = new Parameter("MaximumRows"); maximumRowsParam.DefaultValue = maximumRow.ToString(); QueryStringParameter rootFolderParam = new QueryStringParameter("RootFolder", "RootFolder"); dataSource.SelectParameters.Add(listIdParam); dataSource.SelectParameters.Add(maximumRowsParam); dataSource.SelectParameters.Add(rootFolderParam); dataSource.UpdateParameters.Add(listIdParam); dataSource.DeleteParameters.Add(listIdParam); dataSource.InsertParameters.Add(listIdParam); return dataSource; } private string BuildDataFormParameters() { StringBuilder parameters = new StringBuilder("<ParameterBindings><ParameterBinding Name=\"dvt_apos\" Location=\"Postback;Connection\"/><ParameterBinding Name=\"UserID\" Location=\"CAMLVariable\" DefaultValue=\"CurrentUserName\"/><ParameterBinding Name=\"Today\" Location=\"CAMLVariable\" DefaultValue=\"CurrentDate\"/>"); parameters.Append("<ParameterBinding Name=\"dvt_firstrow\" Location=\"Postback;Connection\"/>"); parameters.Append("<ParameterBinding Name=\"dvt_nextpagedata\" Location=\"Postback;Connection\"/>"); parameters.Append("<ParameterBinding Name=\"dvt_adhocmode\" Location=\"Postback;Connection\"/>"); parameters.Append("<ParameterBinding Name=\"dvt_adhocfiltermode\" Location=\"Postback;Connection\"/>"); parameters.Append("</ParameterBindings>"); return parameters.ToString(); } } } The OnInit method we use to set the list name and the XSL Link property of the Data Form Web Part. We do not have the link to XSL in our Solution so we will add the XSL now: Add a Module in the Visual Studio add menu: Rename Sample.txt in the module to footer.xsl and then copy the XSL from SharePoint Designer Look at elements.xml to where the footer.xsl is being provisioned to which is Assets/footer.xsl, make sure the Web parts xsl link is pointing to this url: Okay we are good to go! Let’s check our features and package: DataFormWebPart should be scoped to site and have the web part: The Footer List feature should be scoped to web and have the Assets module (Okay, I see, a spelling issue but it won’t affect this demo) If everything is correct we should be able to click a couple of sub site feature activations and have our list and web part in a sub site. (In fact this solution can be activated anywhere) Here is the list created at SubSite1 with new data It. Next let’s add the web part on a test page and see if it works as expected: It does! So we now have a repeatable way to use a WSP to move a Data Form Web Part around our sites! Here is a link to the code: DataFormWebPart Solution

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