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  • Managing EntityConnection lifetime

    - by kervin
    There have been many question on managing EntityContext lifetime, e.g. http://stackoverflow.com/questions/813457/instantiating-a-context-in-linq-to-entities I've come to the conclusion that the entity context should be considered a unit-of-work and therefore not reused. Great. But while doing some research for speeding up my database access, I ran into this blog post... Improving Entity Framework Performance The post argues that EFs poor performance compared to other frameworks is often due to the EntityConnection object being created each time a new EntityContext object is needed. To test this I manually created a static EntityConnection in Global.asax.cs Application_Start(). I then converted all my context using statements to using( MyObjContext currContext = new MyObjeContext(globalStaticEFConnection) { .... } This seems to have sped things up a bit without any errors so far as far as I can tell. But is this safe? Does using a applicationwide static EntityConnection introduce race conditions? Best regards, Kervin

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  • Best practice with respect to NPE and multiple expressions on single line

    - by JRL
    I'm wondering if it is an accepted practice or not to avoid multiple calls on the same line with respect to possible NPEs, and if so in what circumstances. For example: getThis().doThat(); vs Object o = getThis(); o.doThat(); The latter is more verbose, but if there is an NPE, you immediately know what is null. However, it also requires creating a name for the variable and more import statements. So my questions around this are: Is this problem something worth designing around? Is it better to go for the first or second possibility? Is the creation of a variable name something that would have an effect performance-wise? Is there a proposal to change the exception message to be able to determine what object is null in future versions of Java ?

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  • Spring/Eclipse 'referenced bean not found' warning when using <import>?

    - by HDave
    I have just broken up a Spring bean configuration file into smaller external files and have used the the "import" directive to include them in my Spring Test application context XML file. But whenever I reference one of the beans from the imported files I get a warning within Eclipse/STS/Spring XML editor complaining that "referenced bean 'foo' not found" Is this is a bug or is it me? It's really annoying because I don't want to disable the warning, yet at my company we try to eliminate all warnings.

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  • OutputStream with ByteArrayOutputStream not writing

    - by Yonatan
    Hey again Internet ! So i'm trying to write out an object to a ByteArray, but for some reason it's not writting anything, which i see by the fact that the return value is 0, and that by the fact that reading it results in an exception. BAoutput = new ByteArrayOutputStream(); Oout = new ObjectOutputStream(BAoutput); Oout.writeObject(receiver); where receiver is an object i get through a parameter. and the exceptions are always the same: at java.io.ObjectInputStream$BlockDataInputStream.peekByte(Unknown Source) at java.io.ObjectInputStream.readObject0(Unknown Source) at java.io.ObjectInputStream.readObject(Unknown Source) Any ideas?

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  • datatable works in C# winform but not ASP.NET

    - by Charles Gargent
    Hi I have created a class that returns a datatable, when I use the class in a c# winform the dataGridView is populted corectly using the following code dataGridView1.DataSource = dbLib.GetData(); However when I try the same thing with ASP.NET I get a Object reference not set to an instance of an object. using the following code GridView1.DataSource = dbLib.GetData(); GridView1.DataBind(); What am I doing wrong / missing Thanks EDIT for the curios here is the dbLib class public static DataTable GetData() { SQLiteConnection cnn = new SQLiteConnection("Data Source=c:\\test.db"); SQLiteCommand cmd = new SQLiteCommand("SELECT count(Message) AS Occurances, Message FROM evtlog GROUP BY Message ORDER BY Occurances DESC LIMIT 25", cnn); cnn.Open(); SQLiteDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection); DataTable dt = new DataTable(); dt.Load(dr); return dt; }

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  • net c# lock statement in data access layer

    - by Pedro Rivera
    I saw a code where they have the data access layer like this: public class CustomerDA{ private static readonly object _sync = new object(); private static readonly CustomerDA _mutex = new CustomerDA(); private CustomerDA(){ } public CustomerDA GetInstance(){ lock(_sync){ return _mutex; } } public DataSet GetCustomers(){ //database SELECT //return a DataSet } public int UpdateCustomer(some parameters){ //update some user } } public class CustomerBO{ public DataSet GetCustomers(){ //some bussiness logic return CustomerDA.GetInstance().GetCustomers(); } } I was using it, but start thinking... "and what if had to build a facebook like application where there are hundreds of thousands of concurrent users? would I be blocking each user from doing his things until the previous user ends his database stuff? and for the Update method, is it useful to LOCK THREADS in the app when database engines already manage concurrency at database server level?" Then I started to think about moving the lock to the GetCustomers and UpdateCustomer methods, but think again: "is it useful at all?"

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  • How can I draw a Rectangle on a PictureBox?

    - by TooFat
    I am trying to just draw a Rectangle on a PictureBox that is on a Form. Writing text like shown here works fine. private void pictureBox1_Paint(object sender, PaintEventArgs e) { using (Font myFont = new Font("Arial", 14)) { e.Graphics.DrawString("Hello .NET Guide!", myFont, Brushes.Green, new Point(2, 2)); } } but when I try to draw a rectangle like so nothing shows up. private void pictureBox1_Paint(object sender, PaintEventArgs e) { Rectangle rect = new Rectangle(); rect.Location = new Point(25, 25); rect.Width = 50; using (Pen pen = new Pen(Color.Red, 2)) { e.Graphics.DrawRectangle(pen, rect); } } What am I missing?

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  • Why does C# not implement GetHashCode for Collections?

    - by Peterdk
    I am porting something from Java to C#. In Java the hashcode of a ArrayList depends on the items in it. In C# I always get the same hashcode from a List... Why is this? For some of my objects the hashcode needs to be different because the objects in their list property make the objects non-equal. I would expect that a hashcode is always unique for the object's state and only equals another hashcode when the object is equal. Am I wrong?

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  • Looking for RESTful Suggestions In Porting ASP.NET to MVC.NET

    - by DaveDev
    I've been tasked with porting/refactoring a Web Application Platform that we have from ASP.NET to MVC.NET. Ideally I could use all the existing platform's configurations to determine the properties of the site that is presented. Is it RESTful to keep a SiteConfiguration object which contains all of our various page configuration data in the System.Web.Caching.Cache? There are a lot of settings that need to be loaded when the user acceses our site so it's inefficient for each user to have to load the same settings every time they access. Some data the SiteConfiguration object contains is as follows and it determines what Master Page / site configuration / style / UserControls are available to the client, public string SiteTheme { get; set; } public string Region { private get; set; } public string DateFormat { get; set; } public string NumberFormat { get; set; } public int WrapperType { private get; set; } public string LabelFileName { get; set; } public LabelFile LabelFile { get; set; } // the following two are the heavy ones // PageConfiguration contains lots of configuration data for each panel on the page public IList<PageConfiguration> Pages { get; set; } // This contains all the configurations for the factsheets we produce public List<ConfiguredFactsheet> ConfiguredFactsheets { get; set; } I was thinking of having a URL structure like this: www.MySite1.com/PageTemplate/UserControl/ the domain determines the SiteConfiguration object that is created, where MySite1.com is SiteId = 1, MySite2.com is SiteId = 2. (and in turn, style, configurations for various pages, etc.) PageTemplate is the View that will be rendered and simply defines a layout for where I'm going to inject the UserControls Can somebody please tell me if I'm completely missing the RESTful point here? I'd like to refactor the platform into MVC because it's better to work in but I want to do it right but with a minimum of reinventing-the-wheel because otherwise it won't get approval. Any suggestions otherwise? Thanks

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  • floor of double(time_t)

    - by plok
    I cannot understand why this throws undefined reference to `floor'": double curr_time = (double)time(NULL); return floor(curr_time); Hasn't it been casted to double, which is what floor receives?

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  • How do I write escape characters verbatim (without escaping) in C# using StreamWriter?

    - by Joel
    I'm writing a utility that takes in a .resx file and creates a javascript object containing properties for all the name/value pairs in the .resx file. This is all well and good, until one of the values in the .resx is This dealer accepts electronic orders. /r/nClick to order {0} from this dealer. I'm adding the name/value pairs to the js object like this: streamWriter.Write(string.Format("\n{0} : \"{1}\"", kvp.Key, kvp.Value)); When kvp.Value = "This dealer accepts electronic orders./r/nClick to order {0} from this dealer." This causes StreamWriter.Write() to actually place a newline in between 'orders.' and 'Click', which naturally screws up my javascript output. I've tried different things with @ and without using string.Format, but I've had no luck. Any suggestions?

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  • Why does this expression not work? JSF

    - by Nitesh Panchal
    Hello, I have a simple problem on .xhtml page. This expression is not working :- <a href="Photos.jsf?albumId=#{item.albumId}&blogId=#{PhotoAlbumsCommonBean.blogId}"> photos </a> I get this error :- Error Parsing /Common/PhotoAlbums.xhtml: Error Traced[line: 20] The reference to entity "blogId" must end with the ';' delimiter. & is causing some kind of error. Thanks in advance :)

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  • Postback problem downloading zip file

    - by Chris Conway
    I've got a problem on a webforms application where a user selects some criteria from dropdowns on the page and hits a button on the page which calls this method: protected void btnSearch_Click(object sender, EventArgs e) They then click on button to download a zip file based on the criteria which calls this method: protected void btnDownload_Click(object sender, EventArgs e) In IE, they are prompted with the bar at the top of the browser that tells them "To help protect your security, Internet Explorer blocked this site from downloading files to your computer". When they click on that bar to download the file, it fires the btnSearch_Click event again. Response.ContentType and Response.AddHeader has been set up correctly. The problem is, that btnSearch appends criteria so basically it is being appended twice and causing problems. Is there something I can do to prevent this? This is a vs2008 web app using c# 3.5 for what it's worth. Thanks!

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  • VB.NET, make a function with return type generic ?

    - by Quandary
    Currently I have written a function to deserialize XML as seen below. How do I change it so I don't have to replace the type every time I want to serialize another object type ? The current object type is cToolConfig. How do I make this function generic ? Public Shared Function DeserializeFromXML(ByRef strFileNameAndPath As String) As XMLhandler.XMLserialization.cToolConfig Dim deserializer As New System.Xml.Serialization.XmlSerializer(GetType(cToolConfig)) Dim srEncodingReader As IO.StreamReader = New IO.StreamReader(strFileNameAndPath, System.Text.Encoding.UTF8) Dim ThisFacility As cToolConfig ThisFacility = DirectCast(deserializer.Deserialize(srEncodingReader), cToolConfig) srEncodingReader.Close() srEncodingReader.Dispose() Return ThisFacility End Function Public Shared Function DeserializeFromXML1(ByRef strFileNameAndPath As String) As System.Collections.Generic.List(Of XMLhandler.XMLserialization.cToolConfig) Dim deserializer As New System.Xml.Serialization.XmlSerializer(GetType(System.Collections.Generic.List(Of cToolConfig))) Dim srEncodingReader As IO.StreamReader = New IO.StreamReader(strFileNameAndPath, System.Text.Encoding.UTF8) Dim FacilityList As System.Collections.Generic.List(Of cToolConfig) FacilityList = DirectCast(deserializer.Deserialize(srEncodingReader), System.Collections.Generic.List(Of cToolConfig)) srEncodingReader.Close() srEncodingReader.Dispose() Return FacilityList End Function

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  • JVMTI: FollowReferences : how to skip Soft/Weak/Phantom references?

    - by Jayan
    I am writing a small code to detect number of objects left behind after certain actions in our tool. This uses FollowReferences() JVMTI-API. This counts instances reachable by all paths. How can I skip paths that included weak/soft/phantom reference? (IterateThroughHeap counts all objects at the moment, so the number is not fully reliable) Thanks, Jayan

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  • Wcf service operation contract change

    - by pdiddy
    I recently added a parameter to one of the method of a wcf. It was a string parameter. The thing is that I didn't update the service reference on the client side but I was still able to call the wcf service ..... Wasn't it suppose to break?

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  • DirectX Resource Leak

    - by srand
    At the end of my DirectX application I get "The Direct3D device has a non-zero reference count, meaning some objects were not released.". The application is large and not written by me, how can I go about debugging what resources are not being released?

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  • Composite Views and View Controllers

    - by BillyK
    Hi, I'm somewhat new to Android and am in the process of designing an application with a couple fairly complex views. One of the views is intended to involve a complex view displaying information associated with model objects and segregated into several different views; the navigation of which is meant to be achieved using sliding effects (i.e. sliding one's finger across the screen to traverse from one screen to the next, etc). The view itself will be used to host multiple sets of views for varying types of model objects, but with a general structure that is reused between them all. As a rough example, the view might come up to display information about a person (the model object), displaying several details views: a view for general information, a view displaying a list of hobbies, and a view displaying a list of other individuals associated with their social network. The same general view, when given a model object representing a particular car would give several different views: A general view with details, A view containing photo images for that vehicle, a view representing locations which it could be purchased from, and a view providing a list of related cars. (NOTE: This is not the real data involved, but is representative of the general intent for the view). The subviews will NOT cover the entire screen real-estate and other features within the view should be both visible and able to be interacted with by the user. The idea here is that there is a general view structure that is reusable and which will manage a set of subviews dynamically generated based upon the type of model object handed to the view. I'm trying to determine the appropriate way to leverage the Android framework in order to best achieve this without violating the integrity of the framework. Basically, I'm trying to determine how to componentize this larger view into reusable units (i.e. general view, model-specific sub-view controllers, and individual detail views). To be more specific, I'm trying to determine if this view is best designed as a composite of several custom View classes or a composite of several Activity classes. I've seen several examples of custom composite views, but they typically are used to compose simple views without complex controllers and without attention to the general Activity lifecycle (i.e. storing and retrieving data related to the model objects, as appropriate). On the other hand, the only real example I've seen regarding a view comprised of a composite of Activities is the TabActivity itself, and that isn't customizable in the fashion that would be necessary for this. Does anyone have any suggestions as to the appropriate way to structure my view to achieve the application framework I'm looking for? Views? Activities? Something else? Any guidance would be appreciated. Thanks in advance.

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  • many-to-many performance concerns with fluent nhibernate.

    - by Ciel
    I have a situation where I have several many-to-many associations. In the upwards of 12 to 15. Reading around I've seen that it's generally believed that many-to-many associations are not 'typical', yet they are the only way I have been able to create the associations appropriate for my case, so I'm not sure how to optimize any further. Here is my basic scenario. class Page { IList<Tag> Tags { get; set; } IList<Modification> Modifications { get; set; } IList<Aspect> Aspects { get; set; } } This is one of my 'core' classes, and coincidentally one of my core tables. Virtually half of the objects in my code can have an IList<Page>, and some of them have IList<T> where T has its own IList<Page>. As you can see, from an object oriented standpoint, this is not really a problem. But from a database standpoint this begins to introduce a lot of junction tables. So far it has worked fine for me, but I am wondering if anyone has any ideas on how I could improve on this structure. I've spent a long time thinking and in order to achieve the appropriate level of association required, I cannot think of any way to improve it. The only thing I have come up with is to make intermediate classes for each object that has an IList<Page>, but that doesn't really do anything that the HasManyToMany does not already do except introduce another class. It does not extend the functionality and, from what I can tell, it does not improve performance. Any thoughts? I am also concerned about Primary Key limits in this scenario. Most everything needs to be able to have these properties, but the Pages cannot be unique to each object, because they are going to be frequently shared and joined between multiple objects. All relationships are one-sided. (That is, a Page has no knowledge of what owns it). Because of this, I also have no Inverse() mapped HasManyToMany collections. Also, I have read the similar question : Usage of ORMs like NHibernate when there are many associations - performance concerns But it really did not answer my concerns.

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  • Conseqences of assigning self

    - by Vegar
    Hi, Found a piece of code today, that I find a little smelly... TMyObject.LoadFromFile(const filename: String); begin if fileExists(filename) then self := TSomeObjectStreamer.ReadObjectFromFile(filename); end; If this code works, it will atleast leak some memory, but does it work? Is OK to assign to self in this manner? What if the streamed object is of a different subclass then the original self? What if the streamed object is of a different class with no common ancestore to the original self?

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  • custom TreeNode and SelectNodeChanged

    - by gilloux
    Hello, I'm working on asp.net I've written a custom Treenode (customTreeNode) that I use to populate a treeview the problem comes up when firing the selectnodechanged event this event give me a TreeNode object and not a customTreeNode and I cannot seem to cast it somehow, does sy have a clue ? Thx here is the code I have populate my tree node.ChildNodes.Add ( customTreeNode = new customTreeNode(site) ); customTreeNode public class customTreeNode : TreeNode { public Guid Id { get; set; } private SPWebEntry _dataContext; public SPWebEntry DataContext { get { return _dataContext; } } public customTreeNode(SPWebEntry DataContext) { _dataContext = DataContext; this.Text = _dataContext.Title; this.Id = _dataContext.Id; } } and the event void treeViewSiteCollection_SelectedNodeChanged(object sender, EventArgs e) { treeViewSiteCollection.SelectedNode; } treeViewSiteCollection.SelectedNode is of type TreeNode and I cannot cast it. Thx guys

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  • Mysterious constraints problem with SQL Server 2000

    - by Ramon
    Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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  • PHP Serialization Will not work correctly.

    - by stevoo
    Hi, I am developing and doing all the testing on a local machine using PHP Version 5.3.3-1ubuntu9.1 version. The host machine is PHP Version 5.2.15. All the seriliaze arguments are identical. The problems is when i try to login the user on my test local machine i do the following : $user->getByUserId($results['id'],$db); $_SESSION['user'] = serialize($user); which retrieved me and serialize the user. and i just load it back when ever i detect that a session exists $user->LoadFromObject(unserialize($_SESSION['user'])); This works perfectly on my test machine. Just transfered the files on the host to see if i can get a beta version out but i keep on getting Warning: unserialize() expects parameter 1 to be string, object given in /home/gamerent/public_html/beta/includes/header.php on line 19 i have noticed that if i echo the $_SESSION['user'] in both system the test will indeed display me the serializated one but the main one will just show me the object and will not serialize the $user

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