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  • Good design of mapping Java Domain objects to Tables (using Hibernate)

    - by M. McKenzie
    Hey guys, I have a question that is more in the realm of design, than implementation. I'm also happy for anyone to point out resources for the answer and I'll gladly, research for myself. Highly simplified Java and SQL: Say I have a business domain POJO called 'Picture' with three attributes. class Picture int idPicture String fileName long size Say I have another business domain POJO called "Item" with 3 attributes Class Item int idItem String itemName ArrayList itemPictures These would be a normal simple relationship. You could say that 'Picture' object, will never exist outside an 'Item' object. Assume a picture belongs only to a specific item, but that an item can have multiple pictures Now - using good database design (3rd Normal Form), we know that we should put items and pictures in their own tables. Here is what I assume would be correct. table Item int idItem (primary key) String itemName table Picture int idPicture (primary key) varchar(45) fileName long size int idItem (foreign key) Here is my question: If you are making Hibernate mapping files for these objects. In the data design, your Picture table needs a column to refer to the Item, so that a foreign key relation can be maintained. However,in your business domain objects - your Picture does not hold a reference/attribute to the idItem - and does not need to know it. A java Picture instance is always instantiated inside an Item instance. If you want to know the Item that the Picture belongs to you are already in the correct scope. Call myItem.getIdItem() and myItem.getItemPictures(),and you have the two pieces of information you need. I know that Hibernate tools have a generator that can auto make your POJO's from looking at your database. My problem stems from the fact that I planned out the data design for this experiment/project first. Then when I went to make the domain java objects, I realized that good design dictated that the objects hold other objects in a nested way. This is obviously different from the way that a database schema is - where all objects(tables) are flat and hold no other complex types within them. What is a good way to reconcile this? Would you: (A) Make the hibernate mapping files so that Picture.hbm.xml has a mapping to the POJO parent's idItem Field (if it's even possible) (B) Add an int attribute in the Picture class to refer to the idItem and set it at instantiation, thus simplifying the hbm.xml mapping file by having all table fields as local attributes in the class (C) Fix the database design because it is wrong, dork. I'd truly appreciate any feedback

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  • AVAudioPlayer lag when calling play

    - by joec
    I have set up an AVAudioPlayer object in viewDidLoad, as per the Apple guidelines, calling prepareToPlay as the last line in viewDidLoad (i have tried in awakeFromNib also). When i press my play button, there is a pause, as it would appear to load the file, then it plays. In audioPlayerDidFinishPlaying, i reload the player with a different sound, and when clicking play for a second time, the file plays instantly. What would cause the player to lag on the first play? Thanks.

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  • Helping linqtosql datacontext use implicit conversion between varchar column in the database and tab

    - by user213256
    I am creating an mssql database table, "Orders", that will contain a varchar(50) field, "Value" containing a string that represents a slightly complex data type, "OrderValue". I am using a linqtosql datacontext class, which automatically types the "Value" column as a string. I gave the "OrderValue" class implicit conversion operators to and from a string, so I can easily use implicit conversion with the linqtosql classes like this: // get an order from the orders table MyDataContext db = new MyDataContext(); Order order = db.Orders(o => o.id == 1); // use implicit converstion to turn the string representation of the order // value into the complex data type. OrderValue value = order.Value; // adjust one of the fields in the complex data type value.Shipping += 10; // use implicit conversion to store the string representation of the complex // data type back in the linqtosql order object order.Value = value; // save changes db.SubmitChanges(); However, I would really like to be able to tell the linqtosql class to type this field as "OrderValue" rather than as "string". Then I would be able to avoid complex code and re-write the above as: // get an order from the orders table MyDataContext db = new MyDataContext(); Order order = db.Orders(o => o.id == 1); // The Value field is already typed as the "OrderValue" type rather than as string. // When a string value was read from the database table, it was implicity converted // to "OrderValue" type. order.Value.Shipping += 10; // save changes db.SubmitChanges(); In order to achieve this desired goal, I looked at the datacontext designer and selected the "Value" field of the "Order" table. Then, in properties, I changed "Type" to "global::MyApplication.OrderValue". The "Server Data Type" property was left as "VarChar(50) NOT NULL" The project built without errors. However, when reading from the database table, I was presented with the following error message: Could not convert from type 'System.String' to type 'MyApplication.OrderValue'. at System.Data.Linq.DBConvert.ChangeType(Object value, Type type) at Read_Order(ObjectMaterializer1 ) at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader2.MoveNext() at System.Linq.Buffer1..ctor(IEnumerable1 source) at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source) at Example.OrdersProvider.GetOrders() at ... etc From the stack trace, I believe this error is happening while reading the data from the table. When presented with converting a string to my custom data type, even though the implicit conversion operators are present, the DBConvert class gets confused and throws an error. Is there anything I can do to help it not get confused and do the implicit conversion? Thanks in advance, and apologies if I have posted in the wrong forum. cheers / Ben

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  • Design patterns and interview question

    - by user160758
    When I was learning to code, I read up on the design patterns like a good boy. Long after this, I started to actually understand them. Design discussions such as those on this site constantly try to make the rules more and more general, which is good. But there is a line, over which it becomes over-analysis starts to feed off itself and as such I think begins to obfuscate the original point - for example the "What's Alternative to Singleton" post and the links contained therein. http://stackoverflow.com/questions/1300655/whats-alternative-to-singleton I say this having been asked in both interviews I’ve had over the last 2 weeks what a singleton is and what criticisms I have of it. I have used it a few times for items such as user data (simple key-value eg. last file opened by this user) and logging (very common i'm sure). I've never ever used it just to have what is essentially global application data, as this is clearly stupid. In the first interview, I reply that I have no criticisms of it. He seemed disappointed by this but as the job wasn’t really for me, I forgot about it. In the next one, I was asked again and, as I wanted this job, I thought about it on the spot and made some objections, similar to those contained in the post linked to above (I suggested use of a factory or dependency injection instead). He seemed happy with this. But my problem is that I have used the singleton without ever using it in this kind of stupid way, which I had to describe on the spot. Using it for global data and the like isn’t something I did then realised was stupid, or read was stupid so didn’t do, it was just something I knew was stupid from the start. Essentially I’m supposed to be able to think of ways of how to misuse a pattern in the interview? Which class of programmers can best answer this question? The best ones? The medium ones? I'm not sure.... And these were both bright guys. I read more than enough to get better at my job but had never actually bothered to seek out criticisms of the most simple of the design patterns like this one. Do people think such questions are valid and that I ought to know the objections off by heart? Or that it is reasonable to be able to work out what other people who are missing the point would do on the fly? Or do you think I’m at least partially right that the question is too unsubtle and that the questions ought to be better thought out in order to make sure only good candidates can answer. PS. Please don’t think I’m saying that I’m just so clever that I know everything automatically - I’ve learnt the hard way like everyone else. But avoiding global data is hardly revolutionary.

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  • convert Arabic numerical to English

    - by hamitay
    i am looking for a way to convert the Arabic numerical string "??????????" to an English numerical string "0123456789" Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click dim Anum as string ="??????????" dim Enum as string =get_egnlishNum(Anum) End Sub private function get_egnlishNum(byval _Anum as string) as string '' converting code end function

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  • ASP.NET Repeater and DataBinder.Eval

    - by Fernando
    I've got a <asp:Repeater> in my webpage, which is bound to a programatically created dataset. The purpose of this repeater is to create an index from A-Z, which, when clicked, refreshes the information on the page. The repeater has a link button like so: <asp:LinkButton ID="indexLetter" Text='<%#DataBinder.Eval(Container.DataItem,"letter")%>' runat="server" CssClass='<%#DataBinder.Eval(Container.DataItem, "cssclass")%>' Enabled='<%#DataBinder.Eval(Container.DataItem,"enabled")%>'></asp:LinkButton> The dataset is created the following way: protected DataSet getIndex(String index) { DataSet ds = new DataSet(); ds.Tables.Add("index"); ds.Tables["index"].Columns.Add("letter"); ds.Tables["index"].Columns.Add("cssclass"); ds.Tables["index"].Columns.Add("enabled"); char alphaStart = Char.Parse("A"); char alphaEnd = Char.Parse("Z"); for (char i = alphaStart; i <= alphaEnd; i++) { String cssclass="", enabled="true"; if (index == i.ToString()) { cssclass = "selected"; enabled = "false"; } ds.Tables["index"].Rows.Add(new Object[3] {i.ToString(),cssclass,enabled }); } return ds; } However, when I run the page, a "Specified cast is not valid exception" is thrown in Text='<%#DataBinder.Eval(Container.DataItem,"letter")'. I have no idea why, I have tried manually casting to String with (String), I've tried a ToString() method, I've tried everything. Also, if in the debugger I add a watch for DataBinder.Eval(Container.DataItem,"letter"), the value it returns is "A", which according to me, should be fine for the Text Property. EDIT: Here is the exception: System.InvalidCastException was unhandled by user code Message="Specified cast is not valid." Source="App_Web_cmu9mtyc" StackTrace: at ASP.savecondition_aspx._DataBinding_control7(Object sender, EventArgs e) in e:\Documents and Settings\Fernando\My Documents\Visual Studio 2008\Projects\mediTrack\mediTrack\saveCondition.aspx:line 45 at System.Web.UI.Control.OnDataBinding(EventArgs e) at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) at System.Web.UI.Control.DataBind() at System.Web.UI.Control.DataBindChildren() InnerException: Any advice will be greatly appreciated, thank you EDIT 2: Fixed! The problem was not in the Text or CSS tags, but in the Enabled tag, I had to cast it to a Boolean value. The problem was that the exception was signaled at the Text tag, I don't know why

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  • Exception RuntimeError

    - by apoorva
    Hi... I am getting 2 following errors: Exception RuntimeError: 'maximum recursion depth exceeded in subclasscheck' in ignored Exception RuntimeError: 'maximum recursion depth exceeded while calling a Python object' in ignored What is the cause for the same.... I have not made any changes to my application since yesterday.... Suddenly today it is giving me this error.... Can upgrading the IE version cause this problem to occur???

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  • Ruby: Dynamically calling available methods raising undefined method (metaprogramming)

    - by user94154
    I have an Activerecord object called Foo: Foo.attribute_names.each do |attribute| puts Foo.find(:all)[0].method(attribute.to_sym).call end Here I'm calling all attributes on this model (ie, querying for each column value). However, sometimes, I'll get an undefined method error. How can ActiveRecord::Base#attribute_names return an attribute name that when converted into its own method call, raises an undefined method error? Thank

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  • MooTools: Fade out element?

    - by JamesBrownIsDead
    I have an Element object that I'm currently calling .hide() on. Instead, I'd like to fade out the opacity of the entire Element (and its children) to 100% (hidden) as a transition effect over maybe 500 ms or 1000 ms. Can Fx.Tween be used for this? Is this possible--does the MooTools framework have an effect like this in its UI library?

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  • What is the best way to call MSWord from C++

    - by Oops
    Hi, my question is: What is the best way to call MSWord from C++ I never did this before. I always used VB6 and the Word-COM-Library: C:\Program Files\Microsoft Office\OfficeXX\MSWORD.olb resp: "Microsoft Word XX.0 Object Library" how should I use/call Word from C++ (VS2010) ? should I use .NET ? (C++CLI) do you have a good step by step explanation? regards and many thanks in advance Oops

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  • Hiding a LinkButton in DataList

    - by sanfra1983
    Hi someone can tell me how to hide a LinkButton inside a DataList? I've tried to do this but I do not work: protected void Page_PreRender(object sender, EventArgs e) { foreach (var item in listanews) { DataList container = dlgestionenews; if (string.IsNullOrEmpty(item.IdNews)) { DataListItem itemdatalist = null; foreach (DataListItem itemdl in container.Items) { foreach (Control control in itemdatalist.Controls) { if (control.GetType().FullName == "LinkButton") { ((LinkButton)control).Visible = false; } } } } } } Thanks!

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  • jQuery Stop non-css animation

    - by Mark
    I'm trying to stop a non-css animation: http://jsbin.com/aqute4/4/edit Button 1 starts the animation nicely, totally lost on how to stop it though, since .stop() seems to need a DOM element... rather than a random object. Thanks in advance. PS: Original code comes from: http://james.padolsey.com/javascript/fun-with-jquerys-animate/

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  • Delegates And Cross Thread Exception

    - by Neo
    Whenever i am updating UI in windows form using delegate it gives me cross thread exception why it is happening like this? is there new thread started for each delegate call ? void Port_DataReceived(object sender, SerialDataReceivedEventArgs e) { //this call delegate to display data clsConnect(statusMsg); } protected void displayResponse(string resp) { //here cross thread exception occur if directly set to lblMsgResp.Text="Test"; if (lblMsgResp.InvokeRequired) { lblMsgResp.Invoke(new MethodInvoker(delegate { lblMsgResp.Text = resp; })); } }

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  • ActionResult - Service

    - by cem
    I bored, writing same code for service and ui. Then i tried to write a converter for simple actions. This converter, converting Service Results to MVC result, seems like good solution for me but anyway i think this gonna opposite MVC pattern. So here, I need help, what you think about algorithm - is this good or not? Thanks ServiceResult - Base: public abstract class ServiceResult { public static NoPermissionResult Permission() { return new NoPermissionResult(); } public static SuccessResult Success() { return new SuccessResult(); } public static SuccessResult<T> Success<T>(T result) { return new SuccessResult<T>(result); } protected ServiceResult(ServiceResultType serviceResultType) { _resultType = serviceResultType; } private readonly ServiceResultType _resultType; public ServiceResultType ResultType { get { return _resultType; } } } public class SuccessResult<T> : ServiceResult { public SuccessResult(T result) : base(ServiceResultType.Success) { _result = result; } private readonly T _result; public T Result { get { return _result; } } } public class SuccessResult : SuccessResult<object> { public SuccessResult() : this(null) { } public SuccessResult(object o) : base(o) { } } Service - eg. ForumService: public ServiceResult Delete(IVUser user, int id) { Forum forum = Repository.GetDelete(id); if (!Permission.CanDelete(user, forum)) { return ServiceResult.Permission(); } Repository.Delete(forum); return ServiceResult.Success(); } Controller: public class BaseController { public ActionResult GetResult(ServiceResult result) { switch (result.ResultType) { case ServiceResultType.Success: var successResult = (SuccessResult)result; return View(successResult.Result); break; case ServiceResultType.NoPermission: return View("Error"); break; default: return View(); break; } } } [HandleError] public class ForumsController : BaseController { [ValidateAntiForgeryToken] [Transaction] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Delete(int id) { ServiceResult result = ForumService.Delete(WebUser.Current, id); /* Custom result */ if (result.ResultType == ServiceResultType.Success) { TempData[ControllerEnums.GlobalViewDataProperty.PageMessage.ToString()] = "The forum was successfully deleted."; return this.RedirectToAction(ec => Index()); } /* Custom result */ /* Execute Permission result etc. */ TempData[ControllerEnums.GlobalViewDataProperty.PageMessage.ToString()] = "A problem was encountered preventing the forum from being deleted. " + "Another item likely depends on this forum."; return GetResult(result); } }

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  • Unable to download trace file

    - by Firas Assaad
    Whenever I switch to DDMS view and start method profiling, I get the following error message when I stop profiling: Method Profiling Error: Unable to download trace file: Remote object doesn't exist! This only happens with 1.6 and 2.1 AVDs, 2.2 and 2.3 work fine. I've been having this problem ever since the latest update to the Eclipse Android plugin. I'm using Eclipse 3.5.2 on Ubuntu 10.04 with Android Development Toolkit version 8.0.0.v201011171904-77661. Let me know if you need any more information.

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  • What is a 'better' approach to query/save from server: DTO or Wcf Data Services?

    - by bonefisher
    From my perspective, the Data Services and their query approach is useful when querying simple object graphs from your server-side domain model. But when you want to query complex dependencies I couldn't create anything good out of it. The classic DTO approach is fine-grained and can handle everything, but the downside is that you have to create Dto classes for every type of server-request which is time consuming and you have to synchronize the Dto type with your domain entity/business logic.

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  • how do i load an image from a DB inside a jsf using managed beans?

    - by RhigoHR
    Hi.. i have a database with some images...could anyone tell me or explain me how could i can load an image in a jsf? I alredy have a managed bean that converts an Image object into a streamcontent...and this streamcontent is called from the page in a tag , but when a i check the source code of the page, there's no src where the image could be loaded. Hope an answer, thx

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  • Problem updating through LINQtoSQL in MVC application using StructureMap, Repository Pattern and UoW

    - by matt
    I have an ASP MVC application using LINQ to SQL for data access. I am trying to use the Repository and Unit of Work patterns, with a service layer consuming the repositories and unit of work. I am experiencing a problem when attempting to perform updates on a particular repository. My application architecture is as follows: My service class: public class MyService { private IRepositoryA _RepositoryA; private IRepositoryB _RepositoryB; private IUnitOfWork _unitOfWork; public MyService(IRepositoryA ARepositoryA, IRepositoryB ARepositoryB, IUnitOfWork AUnitOfWork) { _unitOfWork = AUnitOfWork; _RepositoryA = ARepositoryA; _RepositoryB = ARepositoryB; } public PerformActionOnObject(Guid AID) { MyObject obj = _RepositoryA.GetRecords() .WithID(AID); obj.SomeProperty = "Changed to new value"; _RepositoryA.UpdateRecord(obj); _unitOfWork.Save(); } } Repository interface: public interface IRepositoryA { IQueryable<MyObject> GetRecords(); UpdateRecord(MyObject obj); } Repository LINQtoSQL implementation: public class LINQtoSQLRepositoryA : IRepositoryA { private MyDataContext _DBContext; public LINQtoSQLRepositoryA(IUnitOfWork AUnitOfWork) { _DBConext = AUnitOfWork as MyDataContext; } public IQueryable<MyObject> GetRecords() { return from records in _DBContext.MyTable select new MyObject { ID = records.ID, SomeProperty = records.SomeProperty } } public bool UpdateRecord(MyObject AObj) { MyTableRecord record = (from u in _DB.MyTable where u.ID == AObj.ID select u).SingleOrDefault(); if (record == null) { return false; } record.SomeProperty = AObj.SomePropery; return true; } } Unit of work interface: public interface IUnitOfWork { void Save(); } Unit of work implemented in data context extension. public partial class MyDataContext : DataContext, IUnitOfWork { public void Save() { SubmitChanges(); } } StructureMap registry: public class DataServiceRegistry : Registry { public DataServiceRegistry() { // Unit of work For<IUnitOfWork>() .HttpContextScoped() .TheDefault.Is.ConstructedBy(() => new MyDataContext()); // RepositoryA For<IRepositoryA>() .Singleton() .Use<LINQtoSQLRepositoryA>(); // RepositoryB For<IRepositoryB>() .Singleton() .Use<LINQtoSQLRepositoryB>(); } } My problem is that when I call PerformActionOnObject on my service object, the update never fires any SQL. I think this is because the datacontext in the UnitofWork object is different to the one in RepositoryA where the data is changed. So when the service calls Save() on it's IUnitOfWork, the underlying datacontext does not have any updated data so no update SQL is fired. Is there something I've done wrong in the StrutureMap registry setup? Or is there a more fundamental problem with the design? Many thanks.

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  • How can I provide values for non-grouped columns in NHibernate?

    - by ddc0660
    I have a criteria query: Session.CreateCriteria<Sell043Report>() .SetProjection(.ProjectionList() .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.location)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.agent)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.cusip)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.SettlementDate)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.salePrice)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.foreignFx)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.batchNumber)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.origSaleDate)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.planName)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.dateTimeAdded)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.shares)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.netMoney)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.grossMoney)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.taxWithheld)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.fees))) .List<Sell043Report>(); that generates the following SQL: SELECT this_.location as y0_, this_.agent as y1_, this_.cusip as y2_, this_.SettlementDate as y3_, this_.salePrice as y4_, this_.foreignFx as y5_, this_.batchNumber as y6_, this_.origSaleDate as y7_, this_.planName as y8_, this_.dateTimeAdded as y9_, sum(this_.shares) as y10_, sum(this_.netMoney) as y11_, sum(this_.grossMoney) as y12_, sum(this_.taxWithheld) as y13_, sum(this_.fees) as y14_ FROM MIS_IPS_Sell043Report this_ GROUP BY this_.location, this_.agent, this_.cusip, this_.SettlementDate, this_.salePrice, this_.foreignFx, this_.batchNumber, this_.origSaleDate, this_.planName, this_.dateTimeAdded however the Sell043Report table has additional columns than those listed in the SELECT statement so I'm receiving this error when attempting to get a list of Sell043Reports: System.ArgumentException: The value "System.Object[]" is not of type "xyz.Sell043Report" and cannot be used in this generic collection. I suspect the problem is that I'm not selecting all of the columns for a Sell043Report and so it doesn't know how to map the dataset to the object. I'm trying to achieve something like this: SELECT this_.location as y0_, this_.agent as y1_, this_.cusip as y2_, this_.SettlementDate as y3_, this_.salePrice as y4_, this_.foreignFx as y5_, this_.batchNumber as y6_, this_.origSaleDate as y7_, this_.planName as y8_, this_.dateTimeAdded as y9_, sum(this_.shares) as y10_, sum(this_.netMoney) as y11_, sum(this_.grossMoney) as y12_, sum(this_.taxWithheld) as y13_, sum(this_.fees) as y14_, '' as Address1, '' as Address2 // etc FROM MIS_IPS_Sell043Report this_ GROUP BY this_.location, this_.agent, this_.cusip, this_.SettlementDate, this_.salePrice, this_.foreignFx, this_.batchNumber, this_.origSaleDate, this_.planName, this_.dateTimeAdded How can I do this using NHibernate?

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