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  • How can I implement an interface member in protected ?

    - by Nicolas Dorier
    Hi, I've been quite surprise when I saw the metadata of ReadOnlyObservableCollection in VS 2008... public class ReadOnlyObservableCollection<T> : ReadOnlyCollection<T>, INotifyCollectionChanged, INotifyPropertyChanged { // Summary: // Initializes a new instance of the System.Collections.ObjectModel.ReadOnlyObservableCollection<T> // class that serves as a wrapper for the specified System.Collections.ObjectModel.ObservableCollection<T>. // // Parameters: // list: // The collection to wrap. public ReadOnlyObservableCollection(ObservableCollection<T> list); // Summary: // Occurs when an item is added or removed. protected virtual event NotifyCollectionChangedEventHandler CollectionChanged; // // Summary: // Occurs when a property value changes. protected virtual event PropertyChangedEventHandler PropertyChanged; // Summary: // Raises the System.Collections.ObjectModel.ReadOnlyObservableCollection<T>.CollectionChanged // event. // // Parameters: // args: // The event data. protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs args); // // Summary: // Raises the System.Collections.ObjectModel.ReadOnlyObservableCollection<T>.PropertyChanged // event. // // Parameters: // args: // The event data. protected virtual void OnPropertyChanged(PropertyChangedEventArgs args); } As you can see, CollectionChanged, a member of INotifyCollectionChanged is implemented in protected... and I can't do that in my own class. .NET framework should not compile ! Does someone has an explanation of this mystery ?

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  • Deal with undefined values in code or in the template?

    - by David
    I'm writing a web application (in Python, not that it matters). One of the features is that people can leave comments on things. I have a class for comments, basically like so: class Comment: user = ... # other stuff where user is an instance of another class, class User: name = ... # other stuff And of course in my template, I have <div>${comment.user.name}</div> Problem: Let's say I allow people to post comments anonymously. In that case comment.user is None (undefined), and of course accessing comment.user.name is going to raise an error. What's the best way to deal with that? I see three possibilities: Use a conditional in the template to test for that case and display something different. This is the most versatile solution, since I can change the way anonymous comments are displayed to, say, "Posted anonymously" (instead of "Posted by ..."), but I've often been told that templates should be mindless display machines and not include logic like that. Also, other people might wind up writing alternate templates for the same application, and I feel like I should be making things as easy as possible for the template writer. Implement an accessor method for the user property of a Comment that returns a dummy user object when the real user is undefined. This dummy object would have user.name = 'Anonymous' or something like that and so the template could access it and print its name with no error. Put an actual record in my database corresponding to a user with user.name = Anonymous (or something like that), and just assign that user to any comment posted when nobody's logged in. I know I've seen some real-world systems that operate this way. (phpBB?) Is there a prevailing wisdom among people who write these sorts of systems about which of these (or some other solution) is the best? Any pitfalls I should watch out for if I go one way vs. another? Whoever gives the best explanation gets the checkmark.

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  • Dealing with multiple generics in a method call

    - by thaBadDawg
    I've been dealing a lot lately with abstract classes that use generics. This is all good and fine because I get a lot of utility out of these classes but now it's making for some rather ugly code down the line. For example: abstract class ClassBase<T> { T Property { get; set; } } class MyClass : ClassBase<string> { OtherClass PropertyDetail { get; set; } } This implementation isn't all that crazy, except when I want to reference the abstract class from a helper class and then I have to make a list of generics just to make reference to the implemented class, like this below. class Helper { void HelpMe<C, T>(object Value) where C : ClassBase<T>, new() { DoWork(); } } This is just a tame example, because I have some method calls where the list of where clauses end up being 5 or 6 lines long to handle all of the generic data. What I'd really like to do is class Helper { void HelpMe<C>(object Value) where C : ClassBase, new() { DoWork(); } } but it obviously won't compile. I want to reference ClassBase without having to pass it a whole array of generic classes to get the function to work, but I don't want to reference the higher level classes because there are a dozen of those. Am I the victim of my own cleverness or is there an avenue that I haven't considered yet?

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  • C# generics when T could be an array

    - by bufferz
    I am writing a C# wrapper for a 3rd party library that reads both single values and arrays from a hardware device, but always returns an object[] array even for one value. This requires repeated calls to object[0] when I'd like the end user to be able to use generics to receive either an array or single value. I want to use generics so the callee can use the wrapper in the following ways: MyWrapper<float> mw = new MyWrapper<float>( ... ); float value = mw.Value; //should return float; MyWrapper<float[]> mw = new MyWrapper<float[]>( ... ); float[] values = mw.Value; //should return float[]; In MyWrapper I have the Value property currently as the following: public T Value { get { if(_wrappedObject.Values.Length > 1) return (T)_wrappedObject.Value; //T could be float[]. this doesn't compile. else return (T)_wrappedObject.Values[0]; //T could be float. this compiles. } } I get a compile error in the first case: Cannot convert type 'object[]' to 'T' If I change MyWrapper.Value to T[] I receive: Cannot convert type 'object[]' to 'T[]' Any ideas of how to achieve my goal? Thanks!

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  • Should not a tail-recursive function also be faster?

    - by Balint Erdi
    I have the following Clojure code to calculate a number with a certain "factorable" property. (what exactly the code does is secondary). (defn factor-9 ([] (let [digits (take 9 (iterate #(inc %) 1)) nums (map (fn [x] ,(Integer. (apply str x))) (permutations digits))] (some (fn [x] (and (factor-9 x) x)) nums))) ([n] (or (= 1 (count (str n))) (and (divisible-by-length n) (factor-9 (quot n 10)))))) Now, I'm into TCO and realize that Clojure can only provide tail-recursion if explicitly told so using the recur keyword. So I've rewritten the code to do that (replacing factor-9 with recur being the only difference): (defn factor-9 ([] (let [digits (take 9 (iterate #(inc %) 1)) nums (map (fn [x] ,(Integer. (apply str x))) (permutations digits))] (some (fn [x] (and (factor-9 x) x)) nums))) ([n] (or (= 1 (count (str n))) (and (divisible-by-length n) (recur (quot n 10)))))) To my knowledge, TCO has a double benefit. The first one is that it does not use the stack as heavily as a non tail-recursive call and thus does not blow it on larger recursions. The second, I think is that consequently it's faster since it can be converted to a loop. Now, I've made a very rough benchmark and have not seen any difference between the two implementations although. Am I wrong in my second assumption or does this have something to do with running on the JVM (which does not have automatic TCO) and recur using a trick to achieve it? Thank you.

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  • Convert SQL to LINQ in MVC3 with Ninject

    - by Jeff
    I'm using MVC3 and still learning LINQ. I'm having some trouble trying to convert a query to LINQ to Entities. I want to return an employee object. SELECT E.EmployeeID, E.FirstName, E.LastName, MAX(EO.EmployeeOperationDate) AS "Last Operation" FROM Employees E INNER JOIN EmployeeStatus ES ON E.EmployeeID = ES.EmployeeID INNER JOIN EmployeeOperations EO ON ES.EmployeeStatusID = EO.EmployeeStatusID INNER JOIN Teams T ON T.TeamID = ES.TeamID WHERE T.TeamName = 'MyTeam' GROUP BY E.EmployeeID, E.FirstName, E.LastName ORDER BY E.FirstName, E.LastName What I have is a few tables, but I need to get only the newest status based on the EmployeeOpertionDate. This seems to work fine in SQL. I'm also using Ninject and set my query to return Ienumerable. I played around with the group by option but it then returns IGroupable. Any guidance on converting and returning the property object type would be appreciated. Edit: I started writing this out in LINQ but I'm not sure how to properly return the correct type or cast this. public IQueryable<Employee> GetEmployeesByTeam(int teamID) { var q = from E in context.Employees join ES in context.EmployeeStatuses on E.EmployeeID equals ES.EmployeeID join EO in context.EmployeeOperations on ES.EmployeeStatusID equals EO.EmployeeStatusID join T in context.Teams on ES.TeamID equals T.TeamID where T.TeamName == "MyTeam" group E by E.EmployeeID into G select G; return q; } Edit2: This seems to work for me public IQueryable<Employee> GetEmployeesByTeam(int teamID) { var q = from E in context.Employees join ES in context.EmployeeStatuses on E.EmployeeID equals ES.EmployeeID join EO in context.EmployeeOperations.OrderByDescending(eo => eo.EmployeeOperationDate) on ES.EmployeeStatusID equals EO.EmployeeStatusID join T in context.Teams on ES.TeamID equals T.TeamID where T.TeamID == teamID group E by E.EmployeeID into G select G.FirstOrDefault(); return q; }

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  • Ember nested route. Load more models

    - by user3568719
    JsBin http://jsbin.com/EveQOke/153/ I know how to load more then one model to a route, using Ember.RSVP.hash. (see Jsbin Children menu). I use dynamic part to access one elem from a collection children/1. But i cant load more models to a nested resource. In my example i want to populate all the toys for a select, not just list the toys of the child. I have tried to access the model of the route children App.ChildRoute = Ember.Route.extend({ model: function(param){ return Ember.RSVP.hash({ allToys: this.modelFor("children"), child:this.store.find('child', param.child_id) }); } }); and use its model's toy property (since there have already loaded all of the toys) child.hbs <h4>All avaiable toys</h4> <table> {{#each toy in model.allToys.toys}} <tr> <td>{{toy.name}}</td> </tr> {{/each}} </table>

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  • ObjC internals. Why my duck typing attempt failed?

    - by Piotr Czapla
    I've tried to use id to create duck typing in objective-c. The concept looks fine in theory but failed in practice. I was unable to use any parameters in my methods. The methods were called but parameters were wrong. I was getting BAD_ACESS for objects and random values for primitives. I've attached a simple example below. The question: Does any one knows why the methods parameters are wrong? What is happening under the hood of the objective-c? Note: I'm interest in the details. I know how to make the example below work. An example: I've created a simple class Test that is passed to an other class using property id test. @implementation Test - (void) aSampleMethodWithFloat:(float) f andInt: (int) i { NSLog(@"Parameters: %f, %i\n", f, i); } @end Then in the class the following loop is executed: for (float f=0.0f; f < 100.0f ; f += 0.3f) { [self.test aSampleMethodWithOneFloatParameter: f]; // warning: no method found. } Here is the output that I'm getting. As you can see the method was called but the parameters were wrong. Parameters: 0.000000, 0 Parameters: -0.000000, 1069128089 Parameters: -0.000000, 1070176665 Parameters: 2.000000, 1070805811 Parameters: -0.000000, 1071225241 Parameters: 0.000000, 1071644672 Parameters: 2.000000, 1071854387 Parameters: 36893488147419103232.000000, 1072064102 Parameters: -0.000000, 1072273817 Parameters: -36893488147419103232.000000, 1072483532

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  • Problem executing trackPageview with Google Analytics.

    - by dmrnj
    I'm trying to capture the clicks of certain download links and track them in Google Analytics. Here's my code var links = document.getElementsByTagName("a"); for (var i = 0; i < links.length; i++) { linkpath = links[i].pathname; if( linkpath.match(/\.(pdf|xls|ppt|doc|zip|txt)$/) || links[i].href.indexOf("mode=pdf") >=0 ){ //this matches our search addClickTracker(links[i]); } } function addClickTracker(obj){ if (obj.addEventListener) { obj.addEventListener('click', track , true); } else if (obj.attachEvent) { obj.attachEvent("on" + 'click', track); } } function track(e){ linkhref = (e.srcElement) ? e.srcElement.pathname : this.pathname; pageTracker._trackPageview(linkhref); } Everything up until the pageTracker._trackPageview() call works. In my debugging linkhref is being passed fine as a string. No abnormal characters, nothing. The issue is that, watching my http requests, Google never makes a second call to the tracking gif (as it does if you call this function in an "onclick" property). Calling the tracker from my JS console also works as expected. It's only in my listener. Could it be that my listener is not deferring the default action (loading the new page) before it has a chance to contact Google's servers? I've seen other tracking scripts that do a similar thing without any deferral.

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  • Populate asp.net MVC Index page with data from the database

    - by Sunil Ramu
    I have a web application in which I need to fetch data from the database and display in the index page. As you know, asp.net mvc has given options to edit delete etc... I need to populate the page using the conventional DB way and it uses a stored procedure to retrieve results. I dont want to use LINQ. This is my model entity class using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace LogMVCApp.Models { public class Property { public int Id { get; set; } public string LogInId { get; set; } public string Username { get; set; } public string Action { get; set; } public string Information { get; set; } public bool Passed{get; set; } public string LogType { get; set; } } } and I need to retrieve data using something like this... var conString = ConfigurationManager.ConnectionStrings["connection"].ToString(); var conn = new SqlConnection(conString); var command = new SqlCommand("LogInsert", conn){CommandType=CommandType.StoredProcedure};

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  • Django filters - Using an AllValuesFilter (with a LinkWidget) on a ManyToManyField

    - by magnetix
    This is my first Stack Overflow question, so please let me know if I do anything wrong. I wish to create an AllValues filter on a ManyToMany field using the wonderful django-filters application. Basically, I want to create a filter that looks like it does in the Admin, so I also want to use the LinkWidget too. Unfortunately, I get an error (Invalid field name: 'operator') if I try this the standard way: # Models class Organisation(models.Model): name = models.CharField() ... class Sign(models.Model): name = models.CharField() operator = models.ManyToManyField('Organisation', blank=True) ... # Filter class SignFilter(LinkOrderFilterSet): operator = django_filters.AllValuesFilter(widget=django_filters.widgets.LinkWidget) class Meta: model = Sign fields = ['operator'] I got around this by creating my own filter with the many to many relationship hard coded: # Models class Organisation(models.Model): name = models.CharField() ... class Sign(models.Model): name = models.CharField() operator = models.ManyToManyField('Organisation', blank=True) ... # Filter class MyFilter(django_filters.ChoiceFilter): @property def field(self): cd = {} for row in self.model.objects.all(): orgs = row.operator.select_related().values() for org in orgs: cd[org['id']] = org['name'] choices = zip(cd.keys(), cd.values()) list.sort(choices, key=lambda x:(x[1], x[0])) self.extra['choices'] = choices return super(AllValuesFilter, self).field class SignFilter(LinkOrderFilterSet): operator = MyFilter(widget=django_filters.widgets.LinkWidget) I am new to Python and Django. Can someone think of a more generic/elegant way of doing this?

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  • Hibernate collection mapping challenge

    - by Geln Yang
    Hi, There is a table Item like, code,name 01,parent1 02,parent2 0101,child11 0102,child12 0201,child21 0202,child22 Create a java object and hbm xml to map the table.The Item.parent is a Item whose code is equal to the first two character of its code : class Item{ string code; string name; Item parent; List<Item> children; .... setter/getter.... } <hibernate-mapping> <class name="Item" table="Item"> <id name="code" length="4" type="string"> <generator class="assigned" /> </id> <property name="name" column="name" length="50" not-null="true" /> <!--====================================== --> <many-to-one name="parent" class="Item" not-found="ignore"></many-to-one> <bag name="children"></bag> <!--====================================== --> </class> </hibernate-mapping> How to definition the mapping relationship? Thanks!

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  • iPhone UISlider not visible

    - by John Qualis
    I want to add a UISlider to my app programmatically without using the IB. I am adding a UISlider to my UIViewController using the code below. However I don't see the slider when the view comes up. What am I missing? I am using iPhone SDK 3.1.2. Appreciate any help. @synthesize slider; .... - (void)viewDidLoad { ... ... slider = [[UISlider alloc] initWithFrame: CGRectMake(0, 480 - 80, 300, 20)]; slider.minimumValue = 0.0; slider.maximumValue = 100.0; slider.tag = 0; slider.value = 50; slider.continuous = YES; slider.enabled = YES; [slider addTarget:selfaction:@selector(handleSlider:)forControlEvents:UIControlEventValueChanged]; self.view addSubview:slider]; In the .h file ... UISlider *slider; ... @property (nonatomic, retain) UISlider *slider; - (void) handleSlider:(id)sender;

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  • Spring bean initialization in a web app

    - by EugeneP
    We work with a web application and autowire beans using WebApplicationContextUtils in the init method. Could you clarify some details about bean initialization? The question rises from the static factory method. Suppose there's a bean that is created in a static factory method. As we can see, when the web app is deployed, the ContextLoaderListener initializes all the beans present in Spring xml config file. Now happens such a thing. In the static factory method we run a timer that starts ticking. But in reality we wouldn't want it to start ticking unless the bean is injected into a property of the object ! That is question number one - all the beans are automatically initialized on deploy - correct? And after that when we need an injection, it simply feels the link with the address of the object created during initialization, though OBJECT WAS CREATED ON WEB APP DEPLOY, immediately ! (I assume the default singleton-creation Spring behavior) Second question: are all copies of a web app use the same beans, so all beans are WEB-APP wide, every Spring bean is shared between all the copies of this web app running?

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  • Hosting images from unsecured servers (travelnow.com)

    - by i.am.not.aids
    Hi, My application needs to serve images hosted in travelnow.com (ie. this image) but the application only allow images hosted on a secured server (ie. https). What are my options? TravelNow's suggestion is as follows. How do I do this? Akamai image servers are not secure. Therefore you are unable to serve any of the image urls with a secure HTTPS URL. If you need to serve an image with HTTPS, you must temporarily save the image to your own secure server. This is suggested only for images to be saved as you use them or need them temporarily on the secure page. The hotel images file available from the Affiliate Center provides up to 1.5 million URLs at any time for all properties storing images in the Akamai system. It is not recommended or advised to store all files in advance on your own system since properties change and update images frequently. Although we are not responsible for the images each property stores on the Akamai system, YOU will be responsible for any customer issues arising from displaying outdated or saved image files on your own pages. Thanks! Adrian

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  • "SpeechHypothesized event not raised"

    - by Jankhana
    Hi all, I need to detect the user voice when they pick-up the reciever on the other end. Because Modems usually start playing files (playback terminal) when the first ring goes there. So I planned to use speech recognition when they say "hello", it can start playing the file until wait for playing file. Or even any noise interference it can start speak. I accomplished this with few settings. I found few common words that my engine detects when we speak and the words that comes when it's ringing. It works fine as a stand alone application but if I try to integrate this with my application it just does not raises "SpeechHypothesized" event. I cant understand why this happens. If i see using a break point, the engine is having the delegate assign and invocation property also is initialized properly but than to is doesn't call the event. For calling I'm using C4F tapi manager and for speech recognition i'm using System.Speech library of .Net 3.5. The code for events is as follows : engine.SpeechDetected += new EventHandler<SpeechDetectedEventArgs>(engine_SpeechDetected); engine.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(engine_SpeechRecognized); engine.SpeechHypothesized+=new EventHandler<SpeechHypothesizedEventArgs> (engine_SpeechHypothesized); engine.SpeechRecognitionRejected += new EventHandler<SpeechRecognitionRejectedEventArgs>(engine_SpeechRecognitionRejected); All event's are raised except the speechhypothesized event. Any idea why this happens ????

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  • Reservation Solution for RealEstate integrating with Joomla

    - by Pennf0lio
    Hi, My client needs a Property (Just Land NO Houses) Reservation solution for their existing website (It runs in Joomla). I need some advice/Tips on what approach should I use. I'm looking for an Opensource solution that I can customize to my need. The Scenario: A buyer reserves a lot, A form appears gathers his details after that he/she pays for the reservation. FrontEnd: I need a form builder extension in Joomla that I could build custom form in gathering information (name, email, contact info, address...) from the buyer or the person who is reserving it. After I gather the info I need another extension that will handle the payment for reserving it. This is kinda shopping cart type approach, you see a product and the buy it. But would just need extra details. Backend: I can see all the details of the buyer from their name to the time they paid for a reservation. Thanks! P.S. I'm open to all Ideas. I'm not sure of this approach. Please let me know If you have some good Ideas or example.

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  • How to format individual DropDownlist Items (color, etc.) during onDataBinding event

    - by LesterDove
    Hi, I have a basic DropDownList bound to a ObjectDataSource: <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" DataSourceID="objDataSource1" DataTextField="FieldName" DataValueField="FieldID" /> The DataTable from which it receives the DataTextField and DataValueField values also returns some other interesting information about the records. Say Active = Y/N for simplicity's sake. What I'd like to do is to set the background-color property of the DropDownList Item based on that Active field in the DataSource results. Further, I'd like to do this "in the same pass" as when the DropDownList is bound to the data. So my guess is that it has to happen during OnDataBinding. Things I already know/tried: I could go back and loop through the DropDownList items later. But it would involve embedding loops and re-visiting the DataTable rows and it just seems inefficient int row; for (row = 0; row < DropDownList1.Items.Count - 1; row++) { [[if this row = that data row]] DropDownList1.Items[row].[[DoStuffHere, etc.]] } We already do stuff like this with the GridView OnRowDataBound event, by accessing the GridViewRowEventArgs e. What I seem to be missing is an "OnDropDownListItemBound" event, so to speak. Hope I've been clear and concise. Seems as though it should be easy...

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  • Strategies for Mapping Views in NHibernate

    - by Nathan Fisher
    It seems that NHibernate needs to have an id tag specified as part of the mapping. This presents a problem for views as most of the time (in my experience) a view will not have an Id. I have mapped views before in nhibernate, but they way I did it seemed to be be messy to me. Here is a contrived example of how I am doing it currently. Mapping <class name="ProductView" table="viewProduct" mutable="false" > <id name="Id" type="Guid"> <generator class="guid.comb" /> </id> <property name="Name" /> <!-- more properties --> </class> View SQL Select NewID() as Id, ProductName as Name, --More columns From Product Class public class ProductView { public virtual Id {get; set;} public virtual Name {get; set;} } I don't need an Id for the product or in the case of some views I may not have an id for the view, depending on if I have control over the View Is there a better way of mapping views to objects in nhibernate?

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  • Stop CDATA tags from being output-escaped when writing to XML in C#

    - by Smallgods
    We're creating a system outputting some data to an XML schema. Some of the fields in this schema need their formatting preserved, as it will be parsed by the end system into potentially a Word doc layout. To do this we're using <![CDATA[Some formatted text]]> tags inside of the App.Config file, then putting that into an appropriate property field in a xsd.exe generated class from our schema. Ideally the formatting wouldn't be out problem, but unfortunately thats just how the system is going. The App.Config section looks as follows: <header> <![CDATA[Some sample formatted data]]> </header> The data assignment looks as follows: HeaderSection header = ConfigurationManager.GetSection("header") as HeaderSection; report.header = "<[CDATA[" + header.Header + "]]>"; Finally, the Xml output is handled as follows: xs = new XmlSerializer(typeof(report)); fs = new FileStream (reportLocation, FileMode.Create); xs.Serialize(fs, report); fs.Flush(); fs.Close(); This should in theory produce in the final Xml a section that has information with CDATA tags around it. However, the angled brackets are being converted into &lt; and &gt; I've looked at ways of disabling Outout Escaping, but so far can only find references to XSLT sheets. I've also tried @"<[CDATA[" with the strings, but again no luck. Any help would be appreciated!

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  • Object equality in context of hibernate / webapp

    - by bert
    How do you handle object equality for java objects managed by hibernate? In the 'hibernate in action' book they say that one should favor business keys over surrogate keys. Most of the time, i do not have a business key. Think of addresses mapped to a person. The addresses are keeped in a Set and displayed in a Wicket RefreshingView (with a ReuseIfEquals strategy). I could either use the surrogate id or use all fields in the equals() and hashCode() functions. The problem is that those fields change during the lifetime ob the object. Either because the user entered some data or the id changes due to JPA merge() being called inside the OSIV (Open Session in View) filter. My understanding of the equals() and hashCode() contract is that those should not change during the lifetime of an object. What i have tried so far: equals() based on hashCode() which uses the database id (or super.hashCode() if id is null). Problem: new addresses start with an null id but get an id when attached to a person and this person gets merged() (re-attached) in the osiv-filter. lazy compute the hashcode when hashCode() is first called and make that hashcode @Transitional. Does not work, as merge() returns a new object and the hashcode does not get copied over. What i would need is an ID that gets assigned during object creation I think. What would be my options here? I don't want to introduce some additional persistent property. Is there a way to explicitly tell JPA to assign an ID to an object? Regards

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  • Doubt about instance creation by using Spring framework ???

    - by Arthur Ronald F D Garcia
    Here goes a command object which needs to be populated from a Spring form public class Person { private String name; private Integer age; /** * on-demand initialized */ private Address address; // getter's and setter's } And Address public class Address { private String street; // getter's and setter's } Now suppose the following MultiActionController @Component public class PersonController extends MultiActionController { @Autowired @Qualifier("personRepository") private Repository<Person, Integer> personRepository; /** * mapped To /person/add */ public ModelAndView add(HttpServletRequest request, HttpServletResponse response, Person person) throws Exception { personRepository.add(person); return new ModelAndView("redirect:/home.htm"); } } Because Address attribute of Person needs to be initialized on-demand, i need to override newCommandObject to create an instance of Person to initiaze address property. Otherwise, i will get NullPointerException @Component public class PersonController extends MultiActionController { /** * code as shown above */ @Override public Object newCommandObject(Class clazz) thorws Exception { if(clazz.isAssignableFrom(Person.class)) { Person person = new Person(); person.setAddress(new Address()); return person; } } } Ok, Expert Spring MVC and Web Flow says Options for alternate object creation include pulling an instance from a BeanFactory or using method injection to transparently return a new instance. First option pulling an instance from a BeanFactory can be written as @Override public Object newCommandObject(Class clazz) thorws Exception { /** * Will retrieve a prototype instance from ApplicationContext whose name matchs its clazz.getSimpleName() */ getApplicationContext().getBean(clazz.getSimpleName()); } But what does he want to say by using method injection to transparently return a new instance ??? Can you show how i implement what he said ??? ATT: I know this funcionality can be filled by a SimpleFormController instead of MultiActionController. But it is shown just as an example, nothing else

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  • How can I improve the performance of LinqToSql queries that use EntitySet properties?

    - by DanM
    I'm using LinqToSql to query a small, simple SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of what makes LinqToSql so appealing. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance besides resorting to doing all the joins manually? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view. Update Here are the table definitions for the example I used in my question: create table Order ( Id int identity(1, 1) primary key, ProductName ntext null ) create table Customer ( Id int identity(1, 1) primary key, OrderId int null references Order (Id) )

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  • Hibernate collection mapping Problem

    - by Geln Yang
    Hi, There is a table Item like, code,name 01,parent1 02,parent2 0101,child11 0102,child12 0201,child21 0202,child22 Create a java object and hbm xml to map the table.The Item.parent is a Item whose code is equal to the first two characters of its code : class Item{ String code; String name; Item parent; List<Item> children; .... setter/getter.... } <hibernate-mapping> <class name="Item" table="Item"> <id name="code" length="4" type="string"> <generator class="assigned" /> </id> <property name="name" column="name" length="50" not-null="true" /> <many-to-one name="parent" class="Item" not-found="ignore"> <formula> <![CDATA[ (select i.code,r.name from Item i where (case length(code) when 4 then i.code=SUBSTRING(code,1,2) else false end)) ]]> </formula> </many-to-one> <bag name="children"></bag> </class> </hibernate-mapping> I try to use formula to define the many-to-one relationship,but it doesn't work!Is there something wrong?Or is there other method? Thanks! ps,I use mysql database.

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  • how to check null value of Integer type field in ASP.NET MVC view?

    - by Vikas
    Hi, I have integer type field in database which is having property "Not Null". when i create a view & do a validation, if i left that field blank, it will consider it as 0 so i can not compare it with 0 because if someone insert a value 0 then it will be considered as error! one another problem is that i am using Model error as described in the book "ASP.NET MVC 1.0" @ Scott Gu blog. And I am checking the value in partial class of object (created by LINQ-To-SQL). i.e public partial class Person { public bool IsValid { get { return (GetRuleViolations().Count() == 0); } } public IEnumerable<RuleViolation> GetRuleViolations() { if (String.IsNullOrEmpty(Name)) yield return new RuleViolation("Name is Required", "Name"); if (Age == 0) yield return new RuleViolation("Age is Required", "Age"); yield break; } partial void OnValidate(ChangeAction action) { if (!IsValid) throw new ApplicationException("Rule violations prevent saving"); } } There is also problem with range. Like in database if i declared as smallint i.e. short in c#, now if i exceed that range then it gives error as "A Value is reguired". so finally is there any best way for validation in ASP.NET MVC?

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