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• How can I specify resources in an MVVM view model?

  - by gix

  Suppose I want to show list of objects where each object should have a name and a suitable image (for example MenuItems with Icons, or buttons with text and image). All examples and programs exposed the image in the viewmodel as a path to a PNG file and then bound the Source of an Image to that. But what if I want to use vector images (for example as a DrawingImage in a local ResourceDictionary)? Exposing the DrawingImage from the view model seems bad because I would have to store a reference to the application/window/user control/... (and it is advised to not expose such XAML objects from view models). So a better approach would be to use a string identifier in the view model and then somehow select the appropriate resource. If that identifier is the resource key this snippet looks tempting but does not work: <Image Source="{StaticResource {Binding Icon}}"/> I found two workarounds for that though they did not work for me. The first one was using a normal binding to the icon with a converter that looked up the resource in Application.Current. This does not work if the resource is stored somewhere else I think (and the situation where I initially bumped into this problem had no Application running yet since it was a Window choosing the Application to launch!). The second workaround was using a markup extension derived from StaticResourceExtension that fetched its ResourceKey from the passed binding: <Image Source="{local:BindableStaticResource {Binding Icon}"/> This one looks really neat because it could use local resources, also be used for other things. But when using it I always got an exception ("Resource named {FooIcon} could not be found.", showing the correct XAML file and position of the extension). Even an empty resource extension derived from StaticResourceExtension that just passed the resource key to the base constructor did not work and I cannot explain why. Just using StaticResourceExtension worked just fine. Any ideas how I could fix the second approach, or even better solutions? Edit I noticed that it does work when used directly like this: <Window> <Window.Resources> <DrawingImage x:Key="SomeIcon"/> </Window.Resources> <Image Source="{BindableStaticResource {Binding Icon}}"/> </Window> but fails for example in a DataTemplate. Though a normal StaticResourceExtension works on both occasions so I am puzzled what is going wrong.

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• Constructor versus setter injection

  - by Chris

  Hi, I'm currently designing an API where I wish to allow configuration via a variety of methods. One method is via an XML configuration schema and another method is through an API that I wish to play nicely with Spring. My XML schema parsing code was previously hidden and therefore the only concern was for it to work but now I wish to build a public API and I'm quite concerned about best-practice. It seems that many favor javabean type PoJo's with default zero parameter constructors and then setter injection. The problem I am trying to tackle is that some setter methods implementations are dependent on other setter methods being called before them in sequence. I could write anal setters that will tolerate themselves being called in many orders but that will not solve the problem of a user forgetting to set the appropriate setter and therefore the bean being in an incomplete state. The only solution I can think of is to forget about the objects being 'beans' and enforce the required parameters via constructor injection. An example of this is in the default setting of the id of a component based on the id of the parent components. My Interface public interface IMyIdentityInterface { public String getId(); /* A null value should create a unique meaningful default */ public void setId(String id); public IMyIdentityInterface getParent(); public void setParent(IMyIdentityInterface parent); } Base Implementation of interface: public abstract class MyIdentityBaseClass implements IMyIdentityInterface { private String _id; private IMyIdentityInterface _parent; public MyIdentityBaseClass () {} @Override public String getId() { return _id; } /** * If the id is null, then use the id of the parent component * appended with a lower-cased simple name of the current impl * class along with a counter suffix to enforce uniqueness */ @Override public void setId(String id) { if (id == null) { IMyIdentityInterface parent = getParent(); if (parent == null) { // this may be the top level component or it may be that // the user called setId() before setParent(..) } else { _id = Helpers.makeIdFromParent(parent,getClass()); } } else { _id = id; } } @Override public IMyIdentityInterface getParent() { return _parent; } @Override public void setParent(IMyIdentityInterface parent) { _parent = parent; } } Every component in the framework will have a parent except for the top level component. Using the setter type of injection, then the setters will have different behavior based on the order of the calling of the setters. In this case, would you agree, that a constructor taking a reference to the parent is better and dropping the parent setter method from the interface entirely? Is it considered bad practice if I wish to be able to configure these components using an IoC container? Chris

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• How to access a named element of a derived user control in silverlight ?

  - by Mrt

  Hello, I have a custom base user control in silverlight. <UserControl x:Class="Problemo.MyBaseControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400"> <Grid x:Name="LayoutRoot" Background="White"> <Border Name="HeaderControl" Background="Red" /> </Grid> </UserControl> With the following code behind public partial class MyBaseControl : UserControl { public UIElement Header { get; set; } public MyBaseControl() { InitializeComponent(); Loaded += MyBaseControl_Loaded; } void MyBaseControl_Loaded(object sender, RoutedEventArgs e) { HeaderControl.Child = Header; } } I have a derived control. <me:MyBaseControl x:Class="Problemo.MyControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" xmlns:me="clr-namespace:Problemo" d:DesignHeight="300" d:DesignWidth="400"> <me:MyBaseControl.Header> <TextBlock Name="header" Text="{Binding Text}" /> </me:MyBaseControl.Header> </me:MyBaseControl> With the following code behind. public partial class MyControl : MyBaseControl { public string Text { get; set; } public MyControl(string text) { InitializeComponent(); Text = text; } } I'm trying to set the text value of the header textblock in the derived control. It would be nice to be able to set both ways, i.e. with databinding or in the derived control code behind, but neither work. With the data binding, it doesn't work. If I try in the code behind I get a null reference to 'header'. This is silverlight 4 (not sure if that makes a difference) Any suggestions on how to do with with both databinding and in code ? Cheers

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• Binding problem in C# wpf

  - by Cinaird

  I have a problem whit binding in wpf i have a textbox where i can do some input, then i try to bind the textinput to a custom usercontrol. This work for the usercontrol within RowDetailsTemplate but not in the CellTemplate. For each object in the CellTemplate i get this error output: System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=ScaleTextBox'. BindingExpression:Path=Text; DataItem=null; target element is 'Chart' (Name=''); target property is 'MaxValue' (type 'Int32') My code looks like this: XAML <ToolBarTray ToolBarTray.IsLocked="True" DockPanel.Dock="Top" Height="25"> <ToolBar Name="ButtonBar" > <TextBox Height="23" Name="ScaleTextBox" Width="120" Text="400"/> </ToolBar> </ToolBarTray> <DataGrid ItemsSource="{Binding Path=Items}" AutoGenerateColumns="False" IsReadOnly="True" RowHeight="25" RowDetailsVisibilityMode="VisibleWhenSelected"> <DataGrid.RowDetailsTemplate> <DataTemplate> <StackPanel Orientation="Vertical" > <my:UserControl ItemsSource="{Binding Path=Samples}" MaxValue="{Binding ElementName=ScaleTextBox, Path=Text}"/>--> </StackPanel> </DataTemplate> </DataGrid.RowDetailsTemplate> <DataGrid.Columns> <DataGridTemplateColumn MinWidth="150" Header="Chart" > <DataGridTemplateColumn.CellTemplate> <DataTemplate> <my:UserControl ItemsSource="{Binding Path=Samples}" MaxValue="{Binding ElementName=ScaleTextBox, Path=Text}"/><!-- this is the problem --> </DataTemplate> </DataGridTemplateColumn.CellTemplate> </DataGridTemplateColumn> </DataGrid.Columns> </DataGrid> C# public static readonly DependencyProperty MaxValueProperty = DependencyProperty.Register("MaxValue", typeof(int), typeof(PingChart), new FrameworkPropertyMetadata(MaxValuePropertyChanged)); private static void MaxValuePropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs e) { Console.WriteLine(e.NewValue); } What do i do wrong?

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• Zend Table Relationship Modeling with Composite Key

  - by emeraldjava

  I have a table with a composite primary key using four columns. mysql> describe leaguesummary; +------------------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +------------------------+------------------+------+-----+---------+----------------+ | leagueid | int(10) unsigned | NO | PRI | NULL | auto_increment | | leaguetype | enum('I','T') | NO | PRI | NULL | | | leagueparticipantid | int(10) unsigned | NO | PRI | NULL | | | leaguestandard | int(10) unsigned | NO | | NULL | | | leaguedivision | varchar(5) | NO | PRI | NULL | | | leagueposition | int(10) unsigned | NO | | NULL | | I have the league object modelled as so (all plain enough mappings) <?php class Model_DbTable_League extends Zend_Db_Table_Abstract { protected $_name = 'league'; protected $_primary = 'id'; protected $_dependentTables = array('Model_DbTable_LeagueSummary'); And I've started like this on the new model class. I've mapped a simple reference map which returns all rows linked to the league id. // http://files.zend.com/help/Zend-Framework/zend.db.table.relationships.html // http://naneau.nl/2007/04/21/a-zend-framework-tutorial-part-one/ class Model_DbTable_LeagueSummary extends Zend_Db_Table_Abstract { protected $_name = "leaguesummary"; protected $_primary = array('leagueid', 'leaguetype','leagueparticipantid','leaguedivision'); protected $_referenceMap = array( 'Summary' => array( 'columns' => array('leagueid'), 'refTableClass' => 'Model_DbTable_League', 'refColumns' => array('id') ), ..... ); } ?> The simple case works when called from my controller public function listAction() { // action body $leagueTable = new Model_DbTable_League(); $this->view->leagues = $leagueTable->getLeagues(); $league = $leagueTable->getLeague(6); // work $summary = $league->findDependentRowset('Model_DbTable_LeagueSummary','Summary'); Zend_Debug::dump($summary,"",true); I'm not sure how i can define extra _referenceMap keys which will take extra contraint ket values. I would like to be able to define a set called 'MenA' in which the type and division values are hardcoded, and the league id is taken from the initial rowset. 'MenA' =>array( 'columns' => array('leagueid','leaguetype','leaguedivision'), 'refTableClass' => 'Model_DbTable_League', 'refColumns' => array("id","I","A") ) Is this style of mapping possible ie hardcoding the values into the 'refColumns'. The second crazy idea i had was to pass the variable values in as part of the third param of the findDependentRowset() method. $menA = $league->findDependentRowset('Model_DbTable_LeagueSummary','MenA',array("I","A")); Any suggestions on how I might use the Zend DB Table Relationship mapping correctly to do this would be appreciated. I'm not interested in the plain, old and ugly $db-select(a,b,c)-where(..) style solution.

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• How do I refactor these two C# functions to abstract their logic from the specific class properties

  - by ObligatoryMoniker

  I have two functions whose underlying logic is the same but in one case it sets one property value on a class and in another case it sets a different one. How can I rewrite the following two functions to abstract away as much of the algorithm as possible so that I can make changes in logic in a single place? SetBillingAddress private void SetBillingAddress(OrderAddress newBillingAddress) { BasketHelper basketHelper = new BasketHelper(SiteConstants.BasketName); OrderAddress oldBillingAddress = basketHelper.Basket.Addresses[basketHelper.BillingAddressID]; bool NewBillingAddressIsNotOldBillingAddress = ((oldBillingAddress == null) || (newBillingAddress.OrderAddressId != oldBillingAddress.OrderAddressId)); bool BillingAddressHasBeenPreviouslySet = (oldBillingAddress != null); bool BillingAddressIsNotSameAsShippingAddress = (basketHelper.ShippingAddressID != basketHelper.BillingAddressID); bool NewBillingAddressIsNotShippingAddress = (newBillingAddress.OrderAddressId != basketHelper.ShippingAddressID); if (NewBillingAddressIsNotOldBillingAddress && BillingAddressHasBeenPreviouslySet && BillingAddressIsNotSameAsShippingAddress) { basketHelper.Basket.Addresses.Remove(oldBillingAddress); } if (NewBillingAddressIsNotOldBillingAddress && NewBillingAddressIsNotShippingAddress) { basketHelper.Basket.Addresses.Add(newBillingAddress); } basketHelper.BillingAddressID = newBillingAddress.OrderAddressId; basketHelper.Basket.Save(); } And here is the second one: SetShippingAddress private void SetBillingAddress(OrderAddress newShippingAddress) { BasketHelper basketHelper = new BasketHelper(SiteConstants.BasketName); OrderAddress oldShippingAddress = basketHelper.Basket.Addresses[basketHelper.ShippingAddressID]; bool NewShippingAddressIsNotOldShippingAddress = ((oldShippingAddress == null) || (newShippingAddress.OrderAddressId != oldShippingAddress.OrderAddressId)); bool ShippingAddressHasBeenPreviouslySet = (oldShippingAddress != null); bool ShippingAddressIsNotSameAsBillingAddress = (basketHelper.ShippingAddressID != basketHelper.BillingAddressID); bool NewShippingAddressIsNotBillingAddress = (newShippingAddress.OrderAddressId != basketHelper.BillingAddressID); if (NewShippingAddressIsNotOldShippingAddress && ShippingAddressHasBeenPreviouslySet && ShippingAddressIsNotSameAsBillingAddress) { basketHelper.Basket.Addresses.Remove(oldShippingAddress); } if (NewShippingAddressIsNotOldShippingAddress && NewShippingAddressIsNotBillingAddress) { basketHelper.Basket.Addresses.Add(newShippingAddress); } basketHelper.ShippingAddressID = newShippingAddress.OrderAddressId; basketHelper.Basket.Save(); } My initial thought was that if I could pass a class's property by refernce then I could rewrite the previous functions into something like private void SetPurchaseOrderAddress(OrderAddress newAddress, ref String CurrentChangingAddressIDProperty) and then call this function and pass in either basketHelper.BillingAddressID or basketHelper.ShippingAddressID as CurrentChangingAddressIDProperty but since I can't pass C# properties by reference I am not sure what to do with this code to be able to reuse the logic in both places. Thanks for any insight you can give me.

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• Retrieving/Updating Entity Framework POCO objects that already exist in the ObjectContext

  - by jslatts

  I have a project using Entity Framework 4.0 with POCOs (data is stored in SQL DB, lazyloading is enabled) as follows: public class ParentObject { public int ID {get; set;} public virtual List<ChildObject> children {get; set;} } public class ChildObject { public int ID {get; set;} public int ChildRoleID {get; set;} public int ParentID {get; set;} public virtual ParentObject Parent {get; set;} public virtual ChildRoleObject ChildRole {get; set;} } public class ChildRoleObject { public int ID {get; set;} public string Name {get; set;} public virtual List<ChildObject> children {get; set;} } I want to create a new ChildObject, assign it a role, then add it to an existing ParentObject. Afterwards, I want to send the new ChildObject to the caller. The code below works fine until it tries to get the object back from the database. The newChildObjectInstance only has the ChildRoleID set and does not contain a reference to the actual ChildRole object. I try and pull the new instance back out of the database in order to populate the ChildRole property. Unfortunately, in this case, instead of creating a new instance of ChildObject and assigning it to retreivedChildObject, EF finds the existing ChildObject in the context and returns the in-memory instance, with a null ChildRole property. public ChildObject CreateNewChild(int id, int roleID) { SomeObjectContext myRepository = new SomeObjectContext(); ParentObject parentObjectInstance = myRepository.GetParentObject(id); ChildObject newChildObjectInstance = new ChildObject() { ParentObject = parentObjectInstance, ParentID = parentObjectInstance.ID, ChildRoleID = roleID }; parentObjectInstance.children.Add(newChildObjectInstance); myRepository.Save(); ChildObject retreivedChildObject = myRepository.GetChildObject(newChildObjectInstance.ID); string assignedRoleName = retreivedChildObject.ChildRole.Name; //Throws exception, ChildRole is null return retreivedChildObject; } I have tried setting MergeOptions to Overwrite, calling ObjectContext.Refresh() and ObjectContext.DetectChanges() to no avail... I suspect this is related to the proxy objects that EF injects when working with POCOs. Has anyone run into this issue before? If so, what was the solution?

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• Optimizing tasks to reduce CPU in a trading application

  - by Joel

  Hello, I have designed a trading application that handles customers stocks investment portfolio. I am using two datastore kinds: Stocks - Contains unique stock name and its daily percent change. UserTransactions - Contains information regarding a specific purchase of a stock made by a user : the value of the purchase along with a reference to Stock for the current purchase. db.Model python modules: class Stocks (db.Model): stockname = db.StringProperty(multiline=True) dailyPercentChange=db.FloatProperty(default=1.0) class UserTransactions (db.Model): buyer = db.UserProperty() value=db.FloatProperty() stockref = db.ReferenceProperty(Stocks) Once an hour I need to update the database: update the daily percent change in Stocks and then update the value of all entities in UserTransactions that refer to that stock. The following python module iterates over all the stocks, update the dailyPercentChange property, and invoke a task to go over all UserTransactions entities which refer to the stock and update their value: Stocks.py # Iterate over all stocks in datastore for stock in Stocks.all(): # update daily percent change in datastore db.run_in_transaction(updateStockTxn, stock.key()) # create a task to update all user transactions entities referring to this stock taskqueue.add(url='/task', params={'stock_key': str(stock.key(), 'value' : self.request.get ('some_val_for_stock') }) def updateStockTxn(stock_key): #fetch the stock again - necessary to avoid concurrency updates stock = db.get(stock_key) stock.dailyPercentChange= data.get('some_val_for_stock') # I get this value from outside ... some more calculations here ... stock.put() Task.py (/task) # Amount of transaction per task amountPerCall=10 stock=db.get(self.request.get("stock_key")) # Get all user transactions which point to current stock user_transaction_query=stock.usertransactions_set cursor=self.request.get("cursor") if cursor: user_transaction_query.with_cursor(cursor) # Spawn another task if more than 10 transactions are in datastore transactions = user_transaction_query.fetch(amountPerCall) if len(transactions)==amountPerCall: taskqueue.add(url='/task', params={'stock_key': str(stock.key(), 'value' : self.request.get ('some_val_for_stock'), 'cursor': user_transaction_query.cursor() }) # Iterate over all transaction pointing to stock and update their value for transaction in transactions: db.run_in_transaction(updateUserTransactionTxn, transaction.key()) def updateUserTransactionTxn(transaction_key): #fetch the transaction again - necessary to avoid concurrency updates transaction = db.get(transaction_key) transaction.value= transaction.value* self.request.get ('some_val_for_stock') db.put(transaction) The problem: Currently the system works great, but the problem is that it is not scaling well… I have around 100 Stocks with 300 User Transactions, and I run the update every hour. In the dashboard, I see that the task.py takes around 65% of the CPU (Stock.py takes around 20%-30%) and I am using almost all of the 6.5 free CPU hours given to me by app engine. I have no problem to enable billing and pay for additional CPU, but the problem is the scaling of the system… Using 6.5 CPU hours for 100 stocks is very poor. I was wondering, given the requirements of the system as mentioned above, if there is a better and more efficient implementation (or just a small change that can help with the current implemntation) than the one presented here. Thanks!! Joel

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• SQLAlchemy unsupported type error - and table design issues?

  - by Az

  Hi there, back again with some more SQLAlchemy shenanigans. Let me step through this. My table is now set up as so: engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() students_table = Table('studs', metadata, Column('sid', Integer, primary_key=True), Column('name', String), Column('preferences', Integer), Column('allocated_rank', Integer), Column('allocated_project', Integer) ) metadata.create_all(engine) mapper(Student, students_table) Fairly simple, and for the most part I've been enjoying the ability to query almost any bit of information I want provided I avoid the error cases below. The class it is mapped from is: class Student(object): def __init__(self, sid, name): self.sid = sid self.name = name self.preferences = collections.defaultdict(set) self.allocated_project = None self.allocated_rank = 0 def __repr__(self): return str(self) def __str__(self): return "%s %s" %(self.sid, self.name) Explanation: preferences is basically a set of all the projects the student would prefer to be assigned. When the allocation algorithm kicks in, a student's allocated_project emerges from this preference set. Now if I try to do this: for student in students.itervalues(): session.add(student) session.commit() It throws two errors, one for the allocated_project column (seen below) and a similar error for the preferences column: sqlalchemy.exc.InterfaceError: (InterfaceError) Error binding parameter 4 - probably unsupported type. u'INSERT INTO studs (sid, name, allocated_rank, allocated_project) VALUES (?, ?, ?, ?, ?, ?, ?)' [1101, 'Muffett,M.', 1, 888 Human-spider relationships (Supervisor id: 123)] If I go back into my code I find that, when I'm copying the preferences from the given text files, it actually refers to the Project class which is mapped to a dictionary, using the unique project id's (pid) as keys. Thus, as I iterate through each student via their rank and to the preferences set, it adds not a project id, but the reference to the project id from the projects dictionary. students[sid].preferences[int(rank)].add(projects[int(pid)]) Now this is very useful to me since I can find out all I want to about a student's preferred projects without having to run another check to pull up information about the project id. The form you see in the error has the object print information passed as: return "%s %s (Supervisor id: %s)" %(self.proj_id, self.proj_name, self.proj_sup) My questions are: I'm trying to store an object in a database field aren't I? Would the correct way then, be copying the project information (project id, name, etc) into its own table, referenced by the unique project id? That way I can just have the project id field for one of the student tables just be an integer id and when I need more information, just join the tables? So and so forth for other tables? If the above makes sense, then how does one maintain the relationship with a column of information in one table which is a key index on another table? Does this boil down into a database design problem? Are there any other elegant ways of accomplishing this? Apologies if this is a very long-winded question. It's rather crucial for me to solve this, so I've tried to explain as much as I can, whilst attempting to show that I'm trying (key word here sadly) to understand what could be going wrong.

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• Classes to Entities; Like-class inheritence problems

  - by Stacey

  Beyond work, some friends and I are trying to build a game of sorts; The way we structure some of it works pretty well for a normal object oriented approach, but as most developers will attest this does not always translate itself well into a database persistent approach. This is not the absolute layout of what we have, it is just a sample model given for sake of representation. The whole project is being done in C# 4.0, and we have every intention of using Entity Framework 4.0 (unless Fluent nHibernate can really offer us something we outright cannot do in EF). One of the problems we keep running across is inheriting things in database models. Using the Entity Framework designer, I can draw the same code I have below; but I'm sure it is pretty obvious that it doesn't work like it is expected to. To clarify a little bit; 'Items' have bonuses, which can be of anything. Therefore, every part of the game must derive from something similar so that no matter what is 'changed' it is all at a basic enough level to be hooked into. Sounds fairly simple and straightforward, right? So then, we inherit everything that pertains to the game from 'Unit'. Weights, Measures, Random (think like dice, maybe?), and there will be other such entities. Some of them are similar, but in code they will each react differently. We're having a really big problem with abstracting this kind of thing into a database model. Without 'Enum' support, it is proving difficult to translate into multiple tables that still share a common listing. One solution we've depicted is to use a 'key ring' type approach, where everything that attaches to a character is stored on a 'Ring' with a 'Key', where each Key has a Value that represents a type. This works functionally but we've discovered it becomes very sluggish and performs poorly. We also dislike this approach because it begins to feel as if everything is 'dumped' into one class; which makes management and logical structure difficult to adhere to. I was hoping someone else might have some ideas on what I could do with this problem. It's really driving me up the wall; To summarize; the goal is to build a type (Unit) that can be used as a base type (Table per Type) for generic reference across a relatively global scope, without having to dump everything into a single collection. I can use an Interface to determine actual behavior so that isn't too big of an issue. This is 'roughly' the same idea expressed in the Entity Framework.

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• CakePHP 1.3.4: EmailComponent error - Undefined property: EmailComponent::$Controller

  - by Kevin S.

  I'm trying to develop an invitation system for my website which runs on CakePHP 1.3.4. I am trying to use the built in EmailComponent to send an email. I'm getting this error (expanded): Notice (8): Undefined property: EmailComponent::$Controller [CORE/cake/libs/controller/components/email.php, line 428] Code | Context */ function _render($content) { $viewClass = $this-Controller-view; $content = array( "", "" ) EmailComponent::_render() - CORE/cake/libs/controller/components/email.php, line 428 EmailComponent::send() - CORE/cake/libs/controller/components/email.php, line 368 UsersController::send_quick_add_email() - APP/controllers/users_controller.php, line 77 UsersController::quick_add() - APP/controllers/users_controller.php, line 104 SinglesResultsController::quick_add() - APP/controllers/singles_results_controller.php, line 63 Dispatcher::_invoke() - CORE/cake/dispatcher.php, line 204 Dispatcher::dispatch() - CORE/cake/dispatcher.php, line 171 [main] - APP/webroot/index.php, line 83 I also get the following, which I can expand if necessary: Notice (8): Trying to get property of non-object [CORE/cake/libs/controller/components/email.php, line 428] Notice (8): Undefined property: EmailComponent::$Controller [CORE/cake/libs/controller/components/email.php, line 433] Notice (8): Trying to get property of non-object [CORE/cake/libs/controller/components/email.php, line 433] Notice (8): Undefined property: View::$webroot [CORE/cake/libs/view/view.php, line 805] Warning (2): Cannot modify header information - headers already sent by (output started at /Applications/MAMP/htdocs/cake/cake/libs/debugger.php:673) [CORE/cake/libs/controller/controller.php, line 746] I think that the EmailComponent object holds a reference to the controller it's being called from. I don't know why it's undefined in this case. Here is the code that fails (specifically, it errors on the call to $this-Email-send()): function send_quick_add_email($email) { if($email) { $this->Email->reset(); $this->Email->to = $email; $this->Email->subject = 'Some subject text'; $this->Email->from = '[email protected]'; $this->Email->template = 'email_template'; $this->set('user', $user); $this->set('token', $token); $this->Email->delivery = 'debug'; $this->Email->send(); } } Ok, for more clarification: The main data I am collecting on the site is results of a game played in meatspace. SinglesResultsController has an action, quick_add, which expects email addresses of people not already registered on the site. If the email addresses aren't associated with Users, UsersController::quick_add is called, which creates an inactive user, and sends an invitation email in UsersController::send_quick_add_email() I think the problem is related to the fact that the email isn't being sent in the first controller initialized (SinglesResultsController). Any thoughts on how to make it work? The Email component is declared at the top of both Controllers.

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• Zero code coverage with cobertura 1.9.2 but tests are working

  - by eraonel

  I run the code coverage target: <junit fork="yes" dir="${basedir}" failureProperty="test.failed"> <!-- Note the classpath order: instrumented classes are before the original (uninstrumented) classes. This is important. --> <classpath path="${instrumented.dir}" /> <classpath path="${classes.dir}" /> <classpath refid="classpath" /> <!-- The instrumented classes reference classes used by the Cobertura runtime, so Cobertura and its dependencies must be on your classpath. --> <classpath refid="cobertura.classpath" /> <formatter type="xml" /> <!--<test name="${testcase}" todir="${reports.xml.dir}" if="testcase" />--> <batchtest fork="yes" todir="${reports.xml.dir}"> <fileset dir="${classes.dir}"> <include name="**/generated/AllTests.class" /> </fileset> </batchtest> </junit> <junitreport todir="${reports.xml.dir}"> <fileset dir="${reports.xml.dir}"> <include name="TEST-*.xml" /> </fileset> <report format="frames" todir="${reports.html.dir}" /> </junitreport> Then I get the following output ( when using fork="true"): java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at net.sourceforge.cobertura.util.FileLocker.lock(FileLocker.java:124) at net.sourceforge.cobertura.coveragedata.ProjectData.saveGlobalProjectData(ProjectData.java:331) at net.sourceforge.cobertura.coveragedata.SaveTimer.run(SaveTimer.java:31) at java.lang.Thread.run(Thread.java:595) Caused by: java.io.IOException: No locks available at sun.nio.ch.FileChannelImpl.lock0(Native Method) at sun.nio.ch.FileChannelImpl.lock(FileChannelImpl.java:784) at java.nio.channels.FileChannel.lock(FileChannel.java:865) ... 8 more --------------------------------------- Unable to get lock on /vobs/rnc/rrt/roam2/roamSs/RoamMao_swb/RoamMao_bldu/ant_build/cobertura.ser.lock: null This is known to happen on Linux kernel 2.6.20. Make sure cobertura.jar is in the root classpath of the jvm process running the instrumented code. If the instrumented code is running in a web server, this means cobertura.jar should be in the web server's lib directory. Don't put multiple copies of cobertura.jar in different WEB-INF/lib directories. Only one classloader should load cobertura. It should be the root classloader. I am using Ant 1.7.0 and cobertura 1.9.2. Any ideas why there is no coverage? Test run ok as I see in my target. I have tried to switch java versions ( 1.5.0_06 and 1.6.0_10) but no difference.

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• Memory management with Objective-C Distributed Objects: my temporary instances live forever!

  - by jkp

  I'm playing with Objective-C Distributed Objects and I'm having some problems understanding how memory management works under the system. The example given below illustrates my problem: Protocol.h #import <Foundation/Foundation.h> @protocol DOServer - (byref id)createTarget; @end Server.m #import <Foundation/Foundation.h> #import "Protocol.h" @interface DOTarget : NSObject @end @interface DOServer : NSObject < DOServer > @end @implementation DOTarget - (id)init { if ((self = [super init])) { NSLog(@"Target created"); } return self; } - (void)dealloc { NSLog(@"Target destroyed"); [super dealloc]; } @end @implementation DOServer - (byref id)createTarget { return [[[DOTarget alloc] init] autorelease]; } @end int main() { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; DOServer *server = [[DOServer alloc] init]; NSConnection *connection = [[NSConnection new] autorelease]; [connection setRootObject:server]; if ([connection registerName:@"test-server"] == NO) { NSLog(@"Failed to vend server object"); } else [[NSRunLoop currentRunLoop] run]; [pool drain]; return 0; } Client.m #import <Foundation/Foundation.h> #import "Protocol.h" int main() { unsigned i = 0; for (; i < 3; i ++) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; id server = [NSConnection rootProxyForConnectionWithRegisteredName:@"test-server" host:nil]; [server setProtocolForProxy:@protocol(DOServer)]; NSLog(@"Created target: %@", [server createTarget]); [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:1.0]]; [pool drain]; } return 0; } The issue is that any remote objects created by the root proxy are not released when their proxy counterparts in the client go out of scope. According to the documentation: When an object’s remote proxy is deallocated, a message is sent back to the receiver to notify it that the local object is no longer shared over the connection. I would therefore expect that as each DOTarget goes out of scope (each time around the loop) it's remote counterpart would be dellocated, since there is no other reference to it being held on the remote side of the connection. In reality this does not happen: the temporary objects are only deallocate when the client application quits, or more accurately, when the connection is invalidated. I can force the temporary objects on the remote side to be deallocated by explicitly invalidating the NSConnection object I'm using each time around the loop and creating a new one but somehow this just feels wrong. Is this the correct behaviour from DO? Should all temporary objects live as long as the connection that created them? Are connections therefore to be treated as temporary objects which should be opened and closed with each series of requests against the server? Any insights would be appreciated.

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• File sizing issue in DOS/FAT

  - by Heather

  I've been tasked with writing a data collection program for a Unitech HT630, which runs a proprietary DOS operating system that can run executables compiled for 16-bit MS DOS with some restrictions. I'm using the Digital Mars C/C++ compiler, which is working well thus far. One of the application requirements is that the data file must be human-readable plain text, meaning the file can be imported into Excel or opened by Notepad. I'm using a variable length record format much like CSV that I've successfully implemented using the C standard library file I/O functions. When saving a record, I have to calculate whether the updated record is larger or smaller than the version of the record currently in the data file. If larger, I first shift all records immediately after the current record forward by the size difference calculated before saving the updated record. EOF is extended automatically by the OS to accommodate the extra data. If smaller, I shift all records backwards by my calculated offset. This is working well, however I have found no way to modify the EOF marker or file size to ignore the data after the end of the last record. Most of the time records will grow in size because the data collection program will be filling some of the empty fields with data when saving a record. Records will only shrink in size when a correction is made on an existing entry, or on a normal record save if the descriptive data in the record is longer than what the program reads in memory. In the situation of a shrinking record, after the last record in the file I'm left with whatever data was sitting there before the shift. I have been writing an EOF delimiter into the file after a "shrinking record save" to signal where the end of my records are and space-filling the remaining data, but then I no longer have a clean file until a "growing record save" extends the size of the file over the space-filled area. The truncate() function in unistd.h does not work (I'm now thinking this is for *nix flavors only?). One proposed solution I've seen involves creating a second file and writing all the data you wish to save into that file, and then deleting the original. Since I only have 4MB worth of disk space to use, this works if the file size is less than 2MB minus the size of my program executable and configuration files, but would fail otherwise. It is very likely that when this goes into production, users would end up with a file exceeding 2MB in size. I've looked at Ralph Brown's Interrupt List and the interrupt reference in IBM PC Assembly Language and Programming and I can't seem to find anything to update the file size or similar. Is reducing a file's size without creating a second file even possible in DOS?

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• Windows 7 - pydoc from cmd

  - by Random_Person

  Okay, I'm having one of those moments that makes me question my ability to use a computer. This is not the sort of question I imagined asking as my first SO post, but here goes. Started on Zed's new "Learn Python the Hard Way" since I've been looking to get back into programming after a 10 year hiatus and python was always what I wanted. This book has really spoken to me. That being said, I'm having a serious issue with pydoc from the command. I've got all the directories in c:/python26 in my system path and I can execute pydoc from the command line just fine regardless of pwd - but it accepts no arguments. Doesn't matter what I type, I just get the standard pydoc output telling me the acceptable arguments. Any ideas? For what it's worth, I installed ActivePython as per Zed's suggestion. C:\Users\Chevee>pydoc file pydoc - the Python documentation tool pydoc.py <name> ... Show text documentation on something. <name> may be the name of a Python keyword, topic, function, module, or package, or a dotted reference to a class or function within a module or module in a package. If <name> contains a '\', it is used as the path to a Python source file to document. If name is 'keywords', 'topics', or 'modules', a listing of these things is displayed. pydoc.py -k <keyword> Search for a keyword in the synopsis lines of all available modules. pydoc.py -p <port> Start an HTTP server on the given port on the local machine. pydoc.py -g Pop up a graphical interface for finding and serving documentation. pydoc.py -w <name> ... Write out the HTML documentation for a module to a file in the current directory. If <name> contains a '\', it is treated as a filename; if it names a directory, documentation is written for all the contents. C:\Users\Chevee> EDIT: New information, pydoc works just fine in PowerShell. As a linux user, I have no idea why I'm trying to use cmd anyways--but I'd still love to figure out what's up with pydoc and cmd. EDIT 2: More new information. In cmd... c:\>python c:/python26/lib/pydoc.py file ...works just fine. Everything works just fine with just pydoc in PowerShell without me worrying about pwd, or extensions or paths.

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• WCF Service with callbacks coming from background thread?

  - by Mark Struzinski

  Here is my situation. I have written a WCF service which calls into one of our vendor's code bases to perform operations, such as Login, Logout, etc. A requirement of this operation is that we have a background thread to receive events as a result of that action. For example, the Login action is sent on the main thread. Then, several events are received back from the vendor service as a result of the login. There can be 1, 2, or several events received. The background thread, which runs on a timer, receives these events and fires an event in the wcf service to notify that a new event has arrived. I have implemented the WCF service in Duplex mode, and planned to use callbacks to notify the UI that events have arrived. Here is my question: How do I send new events from the background thread to the thread which is executing the service? Right now, when I call OperationContext.Current.GetCallbackChannel<IMyCallback>(), the OperationContext is null. Is there a standard pattern to get around this? I am using PerSession as my SessionMode on the ServiceContract. UPDATE: I thought I'd make my exact scenario clearer by demonstrating how I'm receiving events from the vendor code. My library receives each event, determines what the event is, and fires off an event for that particular occurrence. I have another project which is a class library specifically for connecting to the vendor service. I'll post the entire implementation of the service to give a clearer picture: [ServiceBehavior( InstanceContextMode = InstanceContextMode.PerSession )] public class VendorServer:IVendorServer { private IVendorService _vendorService; // This is the reference to my class library public VendorServer() { _vendorServer = new VendorServer(); _vendorServer.AgentManager.AgentLoggedIn += AgentManager_AgentLoggedIn; // This is the eventhandler for the event which arrives from a background thread } public void Login(string userName, string password, string stationId) { _vendorService.Login(userName, password, stationId); // This is a direct call from the main thread to the vendor service to log in } private void AgentManager_AgentLoggedIn(object sender, EventArgs e) { var agentEvent = new AgentEvent { AgentEventType = AgentEventType.Login, EventArgs = e }; } } The AgentEvent object contains the callback as one of its properties, and I was thinking I'd perform the callback like this: agentEvent.Callback = OperationContext.Current.GetCallbackChannel<ICallback>(); How would I pass the OperationContext.Current instance from the main thread into the background thread?

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• How to handle ordering of @Rule's when they are dependant on eachother

  - by Lennart Schedin

  I use embedded servers that run inside Junit test cases. Sometimes these servers require a working directory (for example the Apache Directory server). The new @Rule in Junit 4.7 can handle these cases. The TemporaryFolder-Rule can create a temporary directory. A custom ExternalResource-Rule can be created for server. But how do I handle if I want to pass the result from one rule into another: import static org.junit.Assert.assertEquals; import java.io.*; import org.junit.*; import org.junit.rules.*; public class FolderRuleOrderingTest { @Rule public TemporaryFolder folder = new TemporaryFolder(); @Rule public MyNumberServer server = new MyNumberServer(folder); @Test public void testMyNumberServer() throws IOException { server.storeNumber(10); assertEquals(10, server.getNumber()); } /** Simple server that can store one number */ private static class MyNumberServer extends ExternalResource { private TemporaryFolder folder; /** The actual datafile where the number are stored */ private File dataFile; public MyNumberServer(TemporaryFolder folder) { this.folder = folder; } @Override protected void before() throws Throwable { if (folder.getRoot() == null) { throw new RuntimeException("TemporaryFolder not properly initialized"); } //All server data are stored to a working folder File workingFolder = folder.newFolder("my-work-folder"); dataFile = new File(workingFolder, "datafile"); } public void storeNumber(int number) throws IOException { dataFile.createNewFile(); DataOutputStream out = new DataOutputStream(new FileOutputStream(dataFile)); out.writeInt(number); } public int getNumber() throws IOException { DataInputStream in = new DataInputStream(new FileInputStream(dataFile)); return in.readInt(); } } } In this code the folder is sent as a parameter into the server so that the server can create a working directory to store data. However this does not work because Junit processes the rules in reverse order as they are defined in the file. The TemporaryFolder Rule will not be executed before the server Rule. Thus the root-folder in TempraryFolder will be null, resulting that any files are created relative to the current working directory. If I reverse the order of the attributes in my class I get a compile error because I cannot reference a variable before it is defined. I'm using Junit 4.8.1 (because the ordering of rules was fixed a bit from the 4.7 release)

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• Gradual memory leak in loop over contents of QTMovie

  - by Benji XVI

  I have a simple foundation tool that exports every frame of a movie as a .tiff file. Here is the relevant code: NSString* movieLoc = [NSString stringWithCString:argv[1]]; QTMovie *sourceMovie = [QTMovie movieWithFile:movieLoc error:nil]; int i=0; while (QTTimeCompare([sourceMovie currentTime], [sourceMovie duration]) != NSOrderedSame) { // save image of movie to disk NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSString *filePath = [NSString stringWithFormat:@"/somelocation_%d.tiff", i++]; NSData *currentImageData = [[sourceMovie currentFrameImage] TIFFRepresentation]; [currentImageData writeToFile:filePath atomically:NO]; NSLog(@"%@", filePath); [sourceMovie stepForward]; [arp release]; } [pool drain]; return 0; As you can see, in order to prevent very large memory buildups with the various transparently-autoreleased variables in the loop, we create, and flush, an autoreleasepool with every run through the loop. However, over the course of stepping through a movie, the amount of memory used by the program still gradually increases. Instruments is not detecting any memory leaks per se, but the object trace shows certain General Data blocks to be increasing in size. [Edited out reference to slowdown as it doesn't seem to be as much of a problem as I thought.] Edit: let's knock out some parts of the code inside the loop & see what we find out... Test 1 while (banana) { NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSString *filePath = [NSString stringWithFormat:@"/somelocation_%d.tiff", i++]; NSLog(@"%@", filePath); [sourceMovie stepForward]; [arp release]; } Here we simply loop over the whole movie, creating the filename and logging it. Memory characteristics: remains at 15MB usage for the duration. Test 2 while (banana) { NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSImage *image = [sourceMovie currentFrameImage]; [sourceMovie stepForward]; [arp release]; } Here we add back in the creation of the NSImage from the current frame. Memory characteristics: gradually increasing memory usage. RSIZE is at 60MB by frame 200; 75MB by f300. Test 3 while (banana) { NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSImage *image = [sourceMovie currentFrameImage]; NSData *imageData = [image TIFFRepresentation]; [sourceMovie stepForward]; [arp release]; } We've added back in the creation of an NSData object from the NSImage. Memory characteristics: Memory usage is again increasing: 62MB at f200; 75MB at f300. In other words, largely identical. It looks like a memory leak in the underlying system QTMovie uses to do currentFrameImage, to me.

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• My mental block - struggling to learn Objective C

  - by iqessar

  Hello people, this would be my first question after signing up! Anyway heres my question, I did Java at university and I was always told I am a good programmer. However I never pursued it as a career - I went into support and management instead. Im pretty much bored with my job, I have therefore started to learn Objective C so that I can develop apps for the iphone. I am currently watching several different Videos / Books. My problem is that when I go through the Apple documentation, although I understand most of it, sometimes I stumble. I believe that because you/we have the Apple documentation (i.e. Framework references) , everything should be clear, and therefore you should have no need to refer to a book or video (in order to learn how to use a particular class). But I alway do refer to a book and video and subsequently feel guilty as I believe the framework reference should be enough. (I therefore feel I am not up to being a programmer) I also believe that you shouldn't need example code in order to learn how to use a particular class because Apple provides documentation for each class, but AGAIN I find my self googling example code and I find my answer like that - again I feel guilty for doing this. Am I right in saying that Apple documentation is simply not clear? and that its ok to refer to a video/book or google? or forums for that matter? I have proffesional programmers who tell me that I am worrying too much and that I should get on with it and use all the resources that I have. I just cant seem to get round this mental block that I have in my head. When I start a programming project I am able to use the excellent search skills that I have to find the code I need, copy and paste it (yes I do understand it) BUT then I feel guilty telling myself that why didn't you think up the code yourself???? Therefore your not a real programmer, your just good at googling. Currently I am going through 20+ books so that I can learn most of the frameworks, syntax etc to develop iphone apps. I believe if I do this, then when I think of a project I can make it quickly. Should I read a few books, like 2-3 and then just start a project /app , and if I get stuck just google it and get the code I need? Can anybody please answer my questions?

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• Null Exception RelativeLayout

  - by theblixguy

  I am trying to remove objects from my relative layout and replace the background with another image but I get a java.lang.NullPointerException on this line: RelativeLayout ths = (RelativeLayout)findViewById(R.layout.activity_main); Below is my code: package com.ssrij.qrmag; import android.app.Activity; import android.content.Intent; import android.net.Uri; import android.os.Bundle; import android.view.View; import android.view.animation.Animation; import android.view.animation.TranslateAnimation; import android.view.animation.Animation.AnimationListener; import android.widget.Button; import android.widget.RelativeLayout; import android.widget.TextView; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Initialize animations Animation a = new TranslateAnimation(1000,0,0,0); Animation a1 = new TranslateAnimation(1000,0,0,0); Animation a2 = new TranslateAnimation(1000,0,0,0); Animation a3 = new TranslateAnimation(1000,0,0,0); // Set animation durations (ms) a.setDuration(1200); a1.setDuration(1400); a2.setDuration(1600); a3.setDuration(1800); // Get a reference to the objects we want to apply the animation to final TextView v = (TextView)findViewById(R.id.textView1); final TextView v1 = (TextView)findViewById(R.id.textView2); final TextView v2 = (TextView)findViewById(R.id.TextView3); final Button v3 = (Button)findViewById(R.id.tap_scan); // Clear existing animations, just in case... v.clearAnimation(); v1.clearAnimation(); v2.clearAnimation(); v3.clearAnimation(); // Start animating v.startAnimation(a); v1.startAnimation(a1); v2.startAnimation(a2); v3.startAnimation(a3); a1.setAnimationListener(new AnimationListener() { @Override public void onAnimationStart(Animation animation) { // TODO Auto-generated method stub } @Override public void onAnimationRepeat(Animation animation) { // TODO Auto-generated method stub } @Override public void onAnimationEnd(Animation animation) { v.setVisibility(View.INVISIBLE); v1.setVisibility(View.INVISIBLE); v2.setVisibility(View.INVISIBLE); v3.setVisibility(View.INVISIBLE); RelativeLayout ths = (RelativeLayout)findViewById(R.layout.activity_main); ths.setBackgroundResource(R.drawable.blurbg); } }); } public void ScanQr(View v) { // Open the QR Scan page Intent a = new Intent(MainActivity.this, ScanActivity.class); startActivity(a); } } Is there anything that I am doing wrong?

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• Can't access font resource in Silverlight class library

  - by Matt

  I have a reasonably large Silveright 3.0 project on the go, and I'm having issues accessing a couple of custom font resources from within one of the assemblies. I've got a working test solution where I have added a custom font as a resource, and can access it fine from XAML using: <TextBlock Text="Test" FontFamily="FontName.ttf#Font Name" /> The test solution consists of the TestProject.Application and the TestProject.Application.Web projects, with all the fun and games obviously in the TestProject.Application project However, when I try this in my main solution, the fonts refuse to show in the correct type face (instead showing in the default font). There's no difference in the way the font has been added to project between the test solution and the main solution, and the XAML is identical. However, there is a solution layout difference. In the main solution, as well as having a MainApp.Application and MainApp.Application.Web project, I also have a MainApp.Application.ViewModel project and a MainApp.Application.Views project, and the problem piece of XAML is the in the MainApp.Application.Views project (not the .Application project like the test solution). I've tried putting the font into either the .Application or .Application.Views project, tried changing the Build Action to Content, Embedded Resource etc, all to no avail. So, is there an issue accessing font resources from a child assembly that I don't know about, or has anyone successfully done this? My long term need will be to have the valid custom fonts being stored as resources in a separate .Application.FontLibrary assembly that will be on-demand downloaded and cached, and the XAML controls in the .Application.Views project will need to reference this FontLibrary assembly to get the valid fonts. I've also tried xcreating this separate font library assembly, and I can't seem to get the fonts from the second assembly. As some additional information, I've also tried the following font referencing approaches: <TextBlock Text="Test" FontFamily="/FontName.ttf#Font Name" /> <TextBlock Text="Test" FontFamily="pack:application,,,/FontName.ttf#Font Name" /> <TextBlock Text="Test" FontFamily="pack:application,,,/MainApp.Application.Views;/FontName.ttf#Font Name" /> <TextBlock Text="Test" FontFamily="pack:application,,,/MainApp.Application.Views;component/FontName.ttf#Font Name" /> And a few similar variants with different assembly references/sub directories/random semi colons. And so far nothing works... anyone struck this (and preferably solved it)?

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• Virtual member call in a constructor when assigning value to property

  - by comecme

  I have an Abstract class and a Derived class. The abstract class defines an abstract property named Message. In the derived class, the property is implemented by overriding the abstract property. The constructor of the derived class takes a string argument and assigns it to its Message property. In Resharper, this assignment leads to a warning "Virtual member call in constructor". The AbstractClass has this definition: public abstract class AbstractClass { public abstract string Message { get; set; } protected AbstractClass() { } public abstract void PrintMessage(); } And the DerivedClass is as follows: using System; public class DerivedClass : AbstractClass { private string _message; public override string Message { get { return _message; } set { _message = value; } } public DerivedClass(string message) { Message = message; // Warning: Virtual member call in a constructor } public DerivedClass() : this("Default DerivedClass message") {} public override void PrintMessage() { Console.WriteLine("DerivedClass PrintMessage(): " + Message); } } I did find some other questions about this warning, but in those situations there is an actual call to a method. For instance, in this question, the answer by Matt Howels contains some sample code. I'll repeat it here for easy reference. class Parent { public Parent() { DoSomething(); } protected virtual void DoSomething() {}; } class Child : Parent { private string foo; public Child() { foo = "HELLO"; } protected override void DoSomething() { Console.WriteLine(foo.ToLower()); } } Matt doesn't describe on what error the warning would appear, but I'm assuming it will be on the call to DoSomething in the Parent constructor. In this example, I understand what is meant by a virtual member being called. The member call occurs in the base class, in which only a virtual method exists. In my situation however, I don't see why assigning a value to Message would be calling a virtual member. Both the call to and the implementation of the Message property are defined in the derived class. Although I can get rid of the error by making my Derived Class sealed, I would like to understand why this situation is resulting in the warning.

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• Continuous Form, how to add/update records with external connection

  - by Mohgeroth

  EDIT After some more research I found that I cannot use a continuous form with an unbound form since it can only reference a single record at a time. Given that I've altered my question... I have a sample form that pulls out data to enter into a table as an intermediary. Initially the form is unbound and I open connections to two main recordsets. I set the listbox's recordset equal to one of them and the forms recordset equal to the other. The problem is that I cannot add records or update existing ones. Attempting to key into the fields does nothing almost as if the field was locked (Which it is not). Settings of the recordsets are OpenKeyset and LockPessimistic. Tables are not linked, they come from an outside access database seperate from this project and must remain that way. I am using an adodb connection to get the data. Could the separation of the data from the project be causing this? Sample Code from the Form Option Compare Database Option Explicit Private conn As CRobbers_Connections Private exception As CError_Trapping Private mClient_Translations As ADODB.Recordset Private mUnmatched_Clients As ADODB.Recordset Private mExcluded_Clients As ADODB.Recordset //Construction Private Sub Form_Open(Cancel As Integer) Set conn = New CRobbers_Connections Set exception = New CError_Trapping Set mClient_Translations = New ADODB.Recordset Set mUnmatched_Clients = New ADODB.Recordset Set mExcluded_Clients = New ADODB.Recordset mClient_Translations.Open "SELECT * FROM Client_Translation" _ , conn.RBRS_Conn, adOpenKeyset, adLockPessimistic mUnmatched_Clients.Open "SELECT DISTINCT(a.Client) as Client" _ & " FROM Master_Projections a " _ & " WHERE Client NOT IN ( " _ & " SELECT DISTINCT ClientID " _ & " FROM Client_Translation);" _ , conn.RBRS_Conn, adOpenKeyset, adLockPessimistic mExcluded_Clients.Open "SELECT * FROM Clients_Excluded" _ , conn.RBRS_Conn, adOpenKeyset, adLockPessimistic End Sub //Add new record to the client translations Private Sub cmdAddNew_Click() If lstUnconfirmed <> "" Then AddRecord End If End Sub Private Function AddRecord() With mClient_Translations .AddNew .Fields("ClientID") = Me.lstUnconfirmed .Fields("ClientAbbr") = Me.txtTmpShort .Fields("ClientName") = Me.txtTmpLong .Update End With UpdateRecords End Function Private Function UpdateRecords() Me.lstUnconfirmed.Requery End Function //Load events (After construction) Private Sub Form_Load() Set lstUnconfirmed.Recordset = mUnmatched_Clients //Link recordset into listbox Set Me.Recordset = mClient_Translations End Sub //Destruction method Private Sub Form_Close() Set conn = Nothing Set exception = Nothing Set lstUnconfirmed.Recordset = Nothing Set Me.Recordset = Nothing Set mUnmatched_Clients = Nothing Set mExcluded_Clients = Nothing Set mClient_Translations = Nothing End Sub

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• Why is my namespace not recognized in Visual Studio / xaml

  - by msfanboy

  Hello, these are my 2 classes a Attachable Property SelectedItems: code is from here: http://stackoverflow.com/questions/1297643/sync-selecteditems-in-a-muliselect-listbox-with-a-collection-in-viewmodel The namespace TBM.Helper is for sure proper as it works for other classes too. The namespace reference is also in the xaml file: xmlns:Helper="clr_namespace:TBM.Helper" But <ListBox Helper:SelectedItems.Items="{Binding SelectedItems}" ... does not work because = The property 'SelectedItems.Items' does not exist in XML namespace 'clr_namespace:TBM.Helper'. The attachable property 'Items' was not found in type 'SelectedItems What do I have to change ? using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows.Controls; using System.Collections; using System.Windows; namespace TBM.Helper { public static class SelectedItems : DependencyObject { private static readonly DependencyProperty SelectedItemsBehaviorProperty = DependencyProperty.RegisterAttached( "SelectedItemsBehavior", typeof(SelectedItemsBehavior), typeof(ListBox), null); public static readonly DependencyProperty ItemsProperty = DependencyProperty.RegisterAttached( "Items", typeof(IList), typeof(SelectedItems), new PropertyMetadata(null, ItemsPropertyChanged)); public static void SetItems(ListBox listBox, IList list) { listBox.SetValue(ItemsProperty, list); } public static IList GetItems(ListBox listBox) { return listBox.GetValue(ItemsProperty) as IList; } private static void ItemsPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var target = d as ListBox; if (target != null) { GetOrCreateBehavior(target, e.NewValue as IList); } } private static SelectedItemsBehavior GetOrCreateBehavior(ListBox target, IList list) { var behavior = target.GetValue(SelectedItemsBehaviorProperty) as SelectedItemsBehavior; if (behavior == null) { behavior = new SelectedItemsBehavior(target, list); target.SetValue(SelectedItemsBehaviorProperty, behavior); } return behavior; } } } using System.Windows; using System.Windows.Controls; using System.Collections; namespace TBM.Helper { public class SelectedItemsBehavior { private readonly ListBox _listBox; private readonly IList _boundList; public SelectedItemsBehavior(ListBox listBox, IList boundList) { _boundList = boundList; _listBox = listBox; SetSelectedItems(); _listBox.SelectionChanged += OnSelectionChanged; _listBox.DataContextChanged += OnDataContextChanged; } private void SetSelectedItems() { _listBox.SelectedItems.Clear(); foreach (object item in _boundList) { // References in _boundList might not be the same as in _listBox.Items int i = _listBox.Items.IndexOf(item); if (i >= 0) _listBox.SelectedItems.Add(_listBox.Items[i]); } } private void OnDataContextChanged(object sender, DependencyPropertyChangedEventArgs e) { SetSelectedItems(); } private void OnSelectionChanged(object sender, SelectionChangedEventArgs e) { _boundList.Clear(); foreach (var item in _listBox.SelectedItems) _boundList.Add(item); } } }

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• Using empty row as default in a ComboBox with Style "DropDownList"?

  - by Pesche Helfer

  Hi board I am trying to write a method, that takes a ComboBox, a DataTable and a TextBox as arguments. The purpose of it is to filter the members displayed in the ComboBox according to the TextBox.Text. The DataTable contains the entire list of possible entries that will then be filtered. For filtering, I create a DataView of the DataTable, add a RowFilter and then bind this View to the ComboBox as DataSource. To prevent the user from typing into the ComboBox, I choose the DropDownStyle DropDownList. That’s working fine so far, except that the user should also be able to choose nothing / empty line. In fact, this should be the default member to be displayed (to prevent choosing a wrong member by accident, if the user clicks through the dialog too fast). I tried to solve this problem by adding a new Row to the view. While this works for some cases, the main issue here is that any DataTable can be passed to the method. If the DataTable contains columns that cannot be null and don’t contain a default value, I suppose I will raise an error by adding an empty row. A possibility would be to create a view that contains only the column that is defined as DisplayMember, and the one that is defined as ValueMember. Alas, this can’t be done with a view in C#. I would like to avoid creating a true copy of the DataTable at all cost, since who knows how big it will get with time. Do you have any suggestions how to get around this problem? Instead of a view, could I create an object containing two members and assign the DisplayMember and the ValueMember to these members? Would the members be passed as reference (what I hope) or would true copied be created (in which case it would not be a solution)? Thank you very much for your help! Best regards public static void ComboFilter(ComboBox cb, DataTable dtSource, TextBox filterTextBox) { cb.DropDownStyle = ComboBoxStyle.DropDownList; string displayMember = cb.DisplayMember; DataView filterView = new DataView(dtSource); filterView.AddNew(); filterView.RowFilter = displayMember + " LIKE '%" + filterTextBox.Text + "%'"; cb.DataSource = filterView; }

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