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  • How to implement List, Set, and Map in null free design?

    - by Pyrolistical
    Its great when you can return a null/empty object in most cases to avoid nulls, but what about Collection like objects? In Java, Map returns null if key in get(key) is not found in the map. The best way I can think of to avoid nulls in this situation is to return an Entry<T> object, which is either the EmptyEntry<T>, or contains the value T. Sure we avoid the null, but now you can have a class cast exception if you don't check if its an EmptyEntry<T>. Is there a better way to avoid nulls in Map's get(K)? And for argument sake, let's say this language don't even have null, so don't say just use nulls.

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  • Which is the best alternative for Java Serialization?

    - by Alotor
    I'm currently working on a project which needs to persist any kind of objects (of which implementation we don't have any control) so these objects could be recovered afterwards. We can't implement a ORM because we can't restrict the users of our library at development time. Our first alternative was to serialize it with the Java default serialization but we had a lot of trouble recovering the objects when the users started to pass different versions of the same object (attributes changed types, names, ...). We have tried with the XMLEncoder class (transforms an object into a XML), but we have found that there is a lack of functionality (doesn't support Enums for example). Finally, we also tried JAXB but this impose our users to annotate their classes. Any good alternative?

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  • COM/DCOM problem when hosting executable is run as a service

    - by Mitch
    I am struggling for days now with the following problem: We have an executable that hosts a COM server, say x.exe. The COM object is instantiated as follows on the calling site: hRes = CoCreateInstance(CLSID_InterceptX, NULL, CLSCTX_SERVER, IID_IInterceptX, (void**)&pInterceptX); It all works fine when x runs as an regular application. We have a tool (I don't know how it works) that encapsulates x.exe so that it runs as a service under Windows (x.exe is a running process). In this case, we never receive a COM call in x.exe (validated by logging). Here is the weird part: From logging the calling site, I can tell that the COM object has been successfully instantiated and also the call to an interface function does not produce an error (SUCEEDED(hres) is true). Any ideas?

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  • Fluent Nhibernate Automap convention for not-null field

    - by user215015
    Hi, Could some one help, how would I instruct automap to have not-null for a cloumn? public class Paper : Entity { public Paper() { } [DomainSignature] [NotNull, NotEmpty] public virtual string ReferenceNumber { get; set; } [NotNull] public virtual Int32 SessionWeek { get; set; } } But I am getting the following: <column name="SessionWeek"/> I know it can be done using fluent-map. but i would like to know it in auto-mapping way. Many thanks. Regards Robie

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  • Flash receives mouse events under an HTML element when opacity set

    - by Török Gábor
    I have an HTML document with a Flash object and an absolutely positioned HTML element above it. If I set the HTML element's opacity CSS property to any value less than 1, the Flash object (that is actually covered) receives mouse events. This problem cannot be reproduced with pure HTML elements. Furthermore, Flash only receives hover events, so I cannot click below the layer. I put a demonstration of the problem online. I get this behavior in Firefox 3.6, Safari 4.0 and Chrome 5.0 in both Mac and Windows. Flash plugin version 10 is installed. Is it a bug or the the normal and expected behavior? If the latter, then how can I prevent Flash receiving events when it is covered with a translucent layer?

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  • fluent nhibernate m-to-m with column

    - by csetzkorn
    Hi, I am used to hbm files and started using fluent nhibernate recently. Creating an m-to-m relationship between two entities A and B is quite simple In A I create: public virtual IList Bs { get; set; } and then I use: mapping.HasManyToMany(x = x.Bs); That’s it and I can do: A a = new A(); a.Bs.Add(b); My problem is that I would like to have an additional column in my dedicated m-to-m database table which holds the two foreign keys. What is the simplest way to achieve this in FNH? Would I have to create a dedicated entity for the m-to-m realtionship or is there a simpler solution? Thanks. Best wishes, Christian

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  • DataTable.WriteXml on background thread

    - by Sheraz KHan
    I am trying to serealize DataTables in a background thread and it's failing. Any idea [Test] public void Async_Writing_DataTables() { string path = @"C:\Temp\SerialzeData"; if (!Directory.Exists(path)) { Directory.CreateDirectory(path); } Assert.IsTrue(Directory.Exists(path)); Thread thread1 = new Thread(new ThreadStart(delegate { object lockObject = new object(); for (int index = 0; index < 10; index++) { lock (lockObject) { DataTable table = new DataTable("test"); table.WriteXml(Path.Combine(path, table.TableName + index + ".xml")); } } })); thread1.Start(); }

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  • return value from ajax request to another function

    - by stormdrain
    I'm trying to return a value from (transport) to the calling function, but can't seem to get it to work: function createXMLHttpRequest( w ) { var urly = '/users/notes/' + w; var options = { method:'get' , onSuccess: function( transport ) { x = transport.responseText; return x; } , onFailure: function( transport ) { var response = transport.responseText; alert( "FAILED "+ response ); } }; new Ajax.Request( urly, options ); alert( x ); } var ai = $( 'addItem' ); ai.onclick = function() { // -1 indicates new addnote( -1, null ); } x always alerts undefined. Unless I assign x to the Ajax.Request e.g. x=new Ajax.Request(urly,options). It then will alert [Object object]. How can I return the value of transport.responseText to the onclick function?

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  • PHP Interview questions

    - by David
    Hi, does anyone have any thoughts on what would be considered good technicaly interviews for new php programmers. Im not meaning the little questions that are intended to know language specific intricacies but more on larger interview questions that potential employees may take an hour or 2 to solve in their own time and then come back with. Specifically im looking at PHP and object orientated but are there any ideas on suitable problems that a php programmer should be able to solve within a couple of hours? I am thinking that I want to have demonstrated object orientated techniques and also unit testing capabilities but as for that it can be anything.

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  • ASP.NET EnqityDataSource WhereParameters, creates new property.

    - by Alex
    I am trying to populate GridView, using EntityDataSource(code behind), I need to able to sort GridView. However when I sort i get error: A property with name 'aspnet_Users.UserId1' does not exist in metadata for entity type So I beleive it is because I generate where parameter in code behind: ActiveEnqDataSource.WhereParameters.Add(new SessionParameter("aspnet_Users.UserId", TypeCode.Object, "UserName")); Full code is : ActiveEnqDataSource.ConnectionString = db.Connection.ConnectionString; ActiveEnqDataSource.DefaultContainerName = "Entities"; ActiveEnqDataSource.EntitySetName = "Enquiries"; ActiveEnqDataSource.Include = "UserCars.CarModel.CarMake, Category, aspnet_Users"; ActiveEnqDataSource.EnableUpdate = true; ActiveEnqDataSource.EnableInsert = true; ActiveEnqDataSource.EnableDelete = true; ActiveEnqDataSource.AutoGenerateWhereClause = true; ActiveEnqDataSource.WhereParameters.Add(new SessionParameter("aspnet_Users.UserId", TypeCode.Object, "UserName")); Any suggestions? Thank you very much! The gridview itself renders perfectly, only thing I cannot sort it, any "whereParameters" I add, Add 1 to the property e.g UserId1,EnquiryStatus1, ProdauctName1. etc...

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  • accessing a static property via COM

    - by joreg
    is it possible to access a static property of a COM object without creating an instance of the object? my situation is this: i have an unmanaged application (written in delphi). this application exposes a COM-based plugininterface. until now i only wrote managed plugins in c#. plugins provide their info (name, author, ..) via a static property that returns an instance of PluginInfo (which implements IPluginInfo). this static property i can access on the managed plugins using http://managedvcl.com. now i want to write unmanaged plugins on the same interface. i can load them using: plug := CreateComObject(TGuid) as IMyPlugInterface; and they run, but i don't know how to read out their PluginInfo. so the question again is: is there another way than implementing IPluginInfo in the plugin-class and only accessing the info after i have created an instance of the plugin?

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  • strongly typed dataset Insert record with C# problem

    - by Eyla
    Greetings, I'm using strongly typed data-set in windows application and I'm creating table adapter object to call insert function. The problem that there is nothing inserted to the table after calling the function and no error produced. here is my code: public PacketsDBDataSet1TableAdapters.packetsTableAdapter ds = new PacketsDBDataSet1TableAdapters.packetsTableAdapter(); private void btnSavePacketsInFile_Click(object sender, EventArgs e) { byte[] w = null; ds.InsertPackets("s", "s", "s", "s", "s", w); } I'm using same same code with ASP.Net but it is working OK. any advice??

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  • SQL Server 2008 Management Studio doesn't recognize new Schema

    - by Lieven Cardoen
    I have created a new Schema in a database called Contexts. Now when I want to write a query, Management Studio doesn't recognize the tables that belong to the new Schema. It says: 'Invalid object name Contexts.ContextLibraries'... Transact-SQL: INSERT INTO [Contexts].[ContextLibraries] (ChannelId, [IsSystem]) VALUES (@ChannelId, 1) When I try the same thing on my local database, it does work... Any ideas? I did try to change the Default schema for the user from dbo to Contexts but this doesn't work. Also checked Contexts in Schemas owned by this user without success. Update: Apparently the sql query does work but the editor gives a fault saying the object is invalid.

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  • DAO, Spring and Hibernate

    - by EugeneP
    Correct me if anything is wrong. Now when we use Spring DAO for ORM templates, when we use @Transactional attribute, we do not have control over the transaction and/or session when the method is called externally, not within the method. Lazy loading saves resources - less queries to the db, less memory to keep all the collections fetched in the app memory. So, if lazy=false, then everything is fetched, all associated collections, that is not effectively, if there are 10,000 records in a linked set. Now, I have a method in a DAO class that is supposed to return me a User object. It has collections that represent linked tables of the database. I need to get a object by id and then query its collections. Hibernate "failed to lazily initialize a collection" exception occurs when I try to access the linked collection that this DAO method returns. Explain please, what is a workaround here?

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  • kick off a map reduce job from my java/mysql webapp

    - by Brian
    Hi guys, I need a bit of archecture advice. I have a java based webapp, with a JPA based ORM backed onto a mysql relational database. Now, as part of the application I have a batch job that compares thousands of database records with each other. This job has become too time consuming and needs to be parallelized. I'm looking at using mapreduce and hadoop in order to do this. However, I'm not too sure about how to integrate this into my current architecture. I think the easiest initial solution is to find a way to push data from mysql into hadoop jobs. I have done some initial research on this and found the following relevant information and possibilities: 1) https://issues.apache.org/jira/browse/HADOOP-2536 this gives an interesting overview of some inbuilt JDBC support 2) This article http://architects.dzone.com/articles/tools-moving-sql-database describes some third party tools to move data from mysql to hadoop. To be honest I'm just starting out with learning about hbase and hadoop but I really don't know how to integrate this into my webapp. Any advice is greatly appreciated. cheers, Brian

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  • Java servlet and JSP accessing the same session bean

    - by Mykola Golubyev
    Let's say I have simple Login servlet that checks the passed name and creates User object and stores it in a session. User user = new User(); user.setId(name); request.getSession().setAttribute("user", user); response.sendRedirect("index.jsp"); In the index.jsp page I access the user object through jsp:useBean <jsp:useBean id="user" scope="session" class="package.name.User"/> <div class="panel"> Welcome ${user.id} </div> It works so far. The question: is this a valid usage or it is just current implementation uses the same name as the jsp bean id when stores and looks for a bean in a session?

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  • ASP.NET MVC ,Maintaining Model State between Ajax requests

    - by Podders
    problem: On first full page request, my controller invokes an applicationServices Layer (Web Service Proxy to my business tier) in order to populate a collection of current services that is stored in my own controller base class property. This is then to be displayed within a view. Everything within the context of that controller has access to this "Services Collection". Now when i make further calls to the same action method via an AJAX Call, i obviously hitt a different instance of that controller meaning my services collection is empty. So other than re-getting the whole collection again, where would i store this collection so it gets persisted between ajax requests? Should i persist it as a seperate DomainModel Object, Session object?....as ViewData is not working for me obv. Excuse my MVC ignorance :) Any help would be greatly appreciated :)

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  • Is there a standard Java utility to parse XSD files at runtime?

    - by Andrew
    I've been looking around for a way to programmatically parse XSD files to generate an XML mapping so that I can take any XSD file and create a parser that will parse any XML file that conforms to it, and my google-fu has been coming up short. XSOM looks promising, as it will parse an XSD file and make all its attributes available in a straight forward way. Are there any other options or standard libraries available that will produce an XML file parser from an XSD file? [Conclusion] Thanks everyone for your responses, they were a real help. I was able to write implementations using JAXP, Eclipses EMF and in XSOM that all worked as desired. JAXP was very straight forward and easy to learn and do. EMF was actually a pain to get going properly, there were so many jars that had to be included for it to work standalone that I would not recommend it. XSOM was even simpler than the JAXP implementation, so I went with it in the end.

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  • How to temporarily disable read-only 2nd level cache hibernate strategy in Grails ?

    - by fabien7474
    In my grails application, some of my domain classes will never be changed by Users. However, some maintenance work is sometimes necessary, and administrator should be able to create/edit few instances from time to time (let's say twice a year). I would like to set a read-only 2nd level cache strategy for these domain classes (static mapping = { cache usage: 'read-only' } ) AND I would like to be able to 'disable' (in very particular situations) the read-only strategy in order to udate some instances via Grails scaffolding edit view. Is it possible? What do you advise me to do? EDIT: The solution I am implementing is a mix of Pascal and Burt answers (see comments). Both answers are great and helpful. So I got a dilemna for choosing the accepted answer! Anyway, thank you.

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  • Is this a violation of the single responsiblity principle?

    - by L. Moser
    I have the following method and interface: public object ProcessRules(List<IRule> rules) { foreach(IRule rule in rules) { if(EvaluateExpression(rule.Exp) == true) return rule.Result; } //Some error handling here for not hitting any rules } public interface IRule { Expression Exp; Object Result; int Precedence; } Because rules have a precedence, they should actually never be processed out of order. This leads me with (I think) three solutions: Sort rules before passing them into the evaluator. Change the parameter type to something that enforces a sort order. Sort within the evaluator. I like option 3 because it always ensures that it is sorted and I like option 1 because it seems more cohesive. And option 2 seems like a good compromise. Is a scenario like this context specific/subjective, or is there really a best practice to be applied here?

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  • Add data to Django form class using modelformset_factory

    - by dean
    I have a problem where I need to display a lot of forms for detail data for a hierarchical data set. I want to display some relational fields as labels for the forms and I'm struggling with a way to do this in a more robust way. Here is the code... class Category(models.Model): name = models.CharField(max_length=160) class Item(models.Model): category = models.ForeignKey('Category') name = models.CharField(max_length=160) weight = models.IntegerField(default=0) class Meta: ordering = ('category','weight','name') class BudgetValue(models.Model): value = models.IntegerField() plan = models.ForeignKey('Plan') item = models.ForeignKey('Item') I use the modelformset_factory to create a formset of budgetvalue forms for a particular plan. What I'd like is item name and category name for each BudgetValue. When I iterate through the forms each one will be labeled properly. class BudgetValueForm(forms.ModelForm): item = forms.ModelChoiceField(queryset=Item.objects.all(),widget=forms.HiddenInput()) plan = forms.ModelChoiceField(queryset=Plan.objects.all(),widget=forms.HiddenInput()) category = "" < assign dynamically on form creation > item = "" < assign dynamically on form creation > class Meta: model = BudgetValue fields = ('item','plan','value') What I started out with is just creating a dictionary of budgetvalue.item.category.name, budgetvalue.item.name, and the form for each budget value. This gets passed to the template and I render it as I intended. I'm assuming that the ordering of the forms in the formset and the querset used to genererate the formset keep the budgetvalues in the same order and the dictionary is created correctly. That is the budgetvalue.item.name is associated with the correct form. This scares me and I'm thinking there has to be a better way. Any help would be greatly appreciated.

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  • Visual studio winform designer shows design errors as text rather than html

    - by Miki Watts
    All of the sudden, visual studio displays designer errors as plain html text, for example: <DIV id="div1" class="ErrorStyle" width="100%"><span style="font-weight: 600"><br>Object reference not set to an instance of an object. </span><br><a href="" instead of displaying the usual html formatted. I haven't been able to find anything similar to it on google. Before getting this problem, when I tried opening the winform designer, I would get the run/save/cancel dialog of internet explorer for a .tmp file, instead of the designer window. That went away when I found out that I had notepad assigned to the .tmp file type and removed that. Any ideas how to fix this?

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  • C# - Removing items from lists and all references to them.

    - by LiamV
    Hi there, I'm facing a situation where I have dependent objects and I would like to be able to remove an object and all references to it. Say I have an object structure like the code below, with a Branch type which references two Nodes. public class Node { // Has Some Data! } public class Branch { // Contains references to Nodes public Node NodeA public Node NodeB } public class Graph { public List<Node> Nodes; public List<Branch> Branches; } If I remove a Node from the Nodes list in the Graph class, it is still possible that one or more Branch objects still contains a reference to the removed Node, thus retaining it in memory, whereas really what I would quite like would be to set any references to the removed Node to null and let the garbage collection kick in. Other than enumerating through each Branch and checking each Node reference sequentially, are there any smart ideas on how I remove references to the Node in each Branch instance AND indeed any other class which reference the removed Node? Much appreciated, Liam

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  • EF 4 - associations with keys that dont match

    - by Steve Ward
    We're using POCOs and have 2 entities: Item and ItemContact. There are 1 or more contacts per item. Item has as a primary key: ItemID LanguageCode ItemContact has: ItemID ContactID We cant add an association with a referrential constraint as they have differing keys. There isnt a strict primary / foreign key as languageCode isnt in ItemContact and ContactID isnt in Item. How can we go about mapping this with an association for contacts for an item if there isnt a direct link but I still want to see the contacts for an item? One of the entities originates in a database view so it is not possible to add foreign keys to the database Thanks Stephen Ward

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  • Finding the stored procedure that a Crystal Report is using

    - by Brandon
    I need to retrieve the name of the stored procedure that a crystal report is running. Is there any way to do this in C# using the CrystalDecisions.CrystalReports.Engine.ReportDocument object? I can't seem to find a property that will give me the stored procedure name. Is this even possible? I've been through almost all the properties I can think of. The DataDefinition object has collections for the Formula, Parameter, Group Name, and Running Total Fields, but not one for the Database Fields.

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