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  • In Haskell, will calling length on a Lazy ByteString force the entire string into memory?

    - by me2
    I am reading a large data stream using lazy bytestrings, and want to know if at least X more bytes is available while parsing it. That is, I want to know if the bytestring is at least X bytes long. Will calling length on it result in the entire stream getting loaded, hence defeating the purpose of using the lazy bytestring? If yes, then the followup would be: How to tell if it has at least X bytes without loading the entire stream? EDIT: Originally I asked in the context of reading files but understand that there are better ways to determine filesize. Te ultimate solution I need however should not depend on the lazy bytestring source.

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  • Lazy umount or Unmounting a busy disk in Linux

    - by deed02392
    I have read that it is possible to 'umount' a disk that is otherwise busy by using the 'lazy' option. The manpage has this to say about it: umount - unmount file systems -l Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. This option allows a "busy" filesystem to be unmounted. (Requires kernel 2.4.11 or later.) But what would be the point in that? I considered why we dismount partitions at all: To remove the hardware To perform operations on the filesystem that would be unsafe to do while mounted In either of these cases, all a 'lazy' unmount serves IMHO is to make it more difficult to determine if the disk really is dismounted and you can actually proceed with these actions. The only application for umount -l seems to be for inexperienced users to 'feel' like they've achieved something they haven't. Why would you use a lazy unmount?

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  • Lazy HTML attributes wrapping in Internet Explorer

    - by AGS777
    Having encountered this Internet Explorer (all versions) behavior several times previously, I eventually decided to share this most probably useless knowledge. Excuse my lengthy explanations because I am going to show the behavior along with a very simple case when one can come across it inadvertently. Let's say I want to implement some simple templating solution in JavaScript. I wrote an HTML template with an intention to bind data to it on the client side: Please note, that name of the “sys-template” class is just a coincidence. I do not use any ASP.NET AJAX code in this simple example. As you can see we need to replace placeholders (property name wrapped with curly braces) with actual data. Also, as you can see, many of the placeholders are situated within attribute values and it is where the danger lies. I am going to use <a /> element HTML as a template and replace each placeholder pattern with respective properties’ values with a little bit of jQuery like this: You can find complete code along with the contextFormat() method definition at the end of the post. Let’s assume that value for the name property (that we want to put in the title attribute) of the first data item is “first tooltip”. So it consists of two words. When the replacement occurred, title attribute should contain the “first tooltip” text which we are going to see as a tooltip for the <a /> element. But let’s run the sample code in Internet Explorer and check it out. What you’ll see is that only the first word of the supposed “title” attribute’s content is shown. So, were is the rest of my attribute and what happened? The answer is obvious once you see the result of jQuery(“.sys-template”).html() line for the given HTML markup. In IE you’ll get the following <A id={id} class={cssClass} title={name} href="{source}" myAttr="{attr}">Link to {source}</A> See any difference between this HTML and the one shown earlier? No? Then look carefully. While the original HTML of the <a /> element is well-formed and all the attributes are correctly quoted, when you take the same HTML back in Internet Explorer (it doesn’t matter whether you use html() method from jQuery library or IE’s innerHTML directly), you lose attributes’ quotes for some of the attributes. Then, after replacement, we’ll get following HTML for our first data item. I marked the attribute value in question with italic: <A id=1 class=first title=first tooltip href="first.html" myAttr="firstAttr">Link to first.html</A> Now you can easily imagine for yourself what happens when this HTML is inserted into the document and why we do not see the second (and any subsequent words if any) of our title attribute in the tooltip. There are still two important things to note. The first one (and it actually the reason why I named the post “lazy wrapping” is that if value of the HTML attribute does contains spaces in the original HTML, then it WILL be wrapped with quotation marks. For example, if I wrote following on my page (note the trailing space for the title attribute value) <a href="{source}" title="{name}  " id="{id}" myAttr="{attr}" class="{cssClass}">Link to {source}</a> then I would have my placeholder quoted correctly and the result of the replacement would render as expected: The second important thing to note is that there are exceptions for the lazy attributes wrapping rule in IE. As you can see href attribute value did not contain spaces exactly as all the other attributes with placeholders, but it was still returned correctly quoted Custom attribute myAttr is also quoted correctly when returned back from document, though its placeholder value does not contain spaces either. Now, on account of the highly unlikely probability that you found this information useful and need a solution to the problem the aforementioned behavior introduces for Internet Explorer browser, I can suggest a simple workaround – manually quote the mischievous attributes prior the placeholder pattern is replaced. Using the code of contextFormat() method shown below, you would need to add following line right before the return statement: result = result.replace(/=({([^}]+)})/g, '="$1"'); Below please find original sample code:

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  • What good books are out there on program execution models? [on hold]

    - by murungu
    Can anyone out there name a few books that address the topic of program execution models?? I want a book that can answer questions such as... What is the difference between interpreted and compiled languages and what are the performance consequences at runtime?? What is the difference between lazy evaluation, eager evaluation and short circuit evaluation?? Why would one choose to use one evaluation strategy over another?? How do you simulate lazy evaluation in a language that favours eager evaluation??

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  • OOP App Architecture: Which layer does a lazy loader sit in?

    - by JW
    I am planning the implemention an Inheritance Mapper pattern for an application component http://martinfowler.com/eaaCatalog/inheritanceMappers.html One feature it needs to have is for a domain object to reference a large list of aggreageted items (10,000 other domain objects) So I need some kind of lazy loading collection to be passed out of the aggregate root domain object to other domain objects. To keep my (php) model scripts organised i am storing them in two folders: MyComponent\ controllers\ models\ domain\ <- domain objects, DDD repository, DDD factory daccess\ <- PoEAA data mappers, SQL queries etc views\ But now I am racking my brains wondering where my lazy loading collection sits. Any suggestions / justifications for putting it in one place over another another? DDD = Domain Driven Design Patterns, Eric Evans - book PoEAA = Patterns of Application Architecture Patterns, Martin Fowler - book

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  • C# Unit Testing: How do I set a Lazy<T>.ValueCreated to false?

    - by michael paul
    Basically, I have a unit test that gets a singleton instance of a class. Some of my tests required me to mock this singleton, so when I do Foo.Instance I get a different type of instance. The problem is that my checks are passing individually, but failing overall because one test is interfering with another. I tried to do a TestCleanup where I set: Foo_Accessor._instance = null; but that didn't work. What I really need is Foo_Accessor._instance.IsValueCreated = false; (_instance is a Lazy). Any way to unset the Lazy object that I didn't think of?

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  • Why does the entity framework need an ICollection for lazy loading?

    - by Akk
    I want to write a rich domain class such as public class Product { public IEnumerable<Photo> Photos {get; private set;} public void AddPhoto(){...} public void RemovePhoto(){...} } But the entity framework (V4 code first approach) requires an ICollection type for lazy loading! The above code no longer works as designed since clients can bypass the AddPhoto / RemovePhoto method and directly call the add method on ICollection. This is not good. public class Product { public ICollection<Photo> Photos {get; private set;} //Bad public void AddPhoto(){...} public void RemovePhoto(){...} } It's getting really frustrating trying to implement DDD with the EF4. Why did they choose the ICollection for lazy loading? How can i overcome this? Does NHibernate offer me a better DDD experience?

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  • Can lazy loading be considered an example of RAII?

    - by codemonkey
    I have been catching up on my c++ lately, after a couple years of exclusive Objective-C on iOS, and the topic that comes up most on 'new style' c++ is RAII To make sure I understand RAII concept correctly, would you consider Objective-C lazy loading property accessors a type of RAII? For example, check the following access method - (NSArray *)items { if(_items==nil) { _items=[[NSArray alloc] initWithCapacity:10]; } return _items } Would this be considered an example of RAII? If not, can you please explain where I'm mistaken?

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  • Mirroring git and mercurial repos the lazy way

    - by Greg Malcolm
    I maintain Python Koans on mirrored on both Github using git and Bitbucket using mercurial. I get pull requests from both repos but it turns out keeping the two repos in sync is pretty easy. Here is how it's done... Assuming I’m starting again on a clean laptop, first I clone both repos ~/git $ hg clone https://bitbucket.org/gregmalcolm/python_koans ~/git $ git clone [email protected]:gregmalcolm/python_koans.git python_koans2 The only thing that makes a folder a git or mercurial repository is the .hg folder in the root of python_koans and the .git folder in the root of python_koans2. So I just need to move the .git folder over into the python_koans folder I'm using for mercurial: ~/git $ rm -rf python_koans/.git ~/git $ mv python_koans2/.git python_koans ~/git $ ls -la python_koans total 48 drwxr-xr-x 11 greg staff 374 Mar 17 15:10 . drwxr-xr-x 62 greg staff 2108 Mar 17 14:58 .. drwxr-xr-x 12 greg staff 408 Mar 17 14:58 .git -rw-r--r-- 1 greg staff 34 Mar 17 14:54 .gitignore drwxr-xr-x 13 greg staff 442 Mar 17 14:54 .hg -rw-r--r-- 1 greg staff 48 Mar 17 14:54 .hgignore -rw-r--r-- 1 greg staff 365 Mar 17 14:54 Contributor Notes.txt -rw-r--r-- 1 greg staff 1082 Mar 17 14:54 MIT-LICENSE -rw-r--r-- 1 greg staff 5765 Mar 17 14:54 README.txt drwxr-xr-x 10 greg staff 340 Mar 17 14:54 python 2 drwxr-xr-x 10 greg staff 340 Mar 17 14:54 python 3 That’s about it! Now git and mercurial are tracking files in the same folder. Of course you will still need to set up your .gitignore to ignore mercurial’s dotfiles and .hgignore to ignore git’s dotfiles or there will be squabbling in the backseat. ~/git $ cd python_koans/ ~/git/python_koans $ cat .gitignore *.pyc *.swp .DS_Store answers .hg <-- Ignore mercurial ~/git/python_koans $ cat .hgignore syntax: glob *.pyc *.swp .DS_Store answers .git <-- Ignore git Because both my mirrors are both identical as far as tracked files are concerned I won’t yet see anything if I check statuses at this point: ~/git/python_koans $ git status # On branch master nothing to commit (working directory clean) ~/git/python_koans $ hg status ~/git/python_koans But how about if I accept a pull request from the bitbucket (mercuial) site? ~/git/python_koans $ hg status ~/git/python_koans $ git status # On branch master # Your branch is behind 'origin/master' by 1 commit, and can be fast-forwarded. # # Changed but not updated: # (use "git add <file>..." to update what will be committed) # (use "git checkout -- <file>..." to discard changes in working directory) # # modified: python 2/koans/about_decorating_with_classes.py # modified: python 2/koans/about_iteration.py # modified: python 2/koans/about_with_statements.py # modified: python 3/koans/about_decorating_with_classes.py # modified: python 3/koans/about_iteration.py # modified: python 3/koans/about_with_statements.py Mercurial doesn’t have any changes to track right now, but git has changes. Commit and push them up to github and balance is restored to the force: ~/git/python_koans $ git commit -am "Merge from bitbucket mirror: 'gpiancastelli - Fix for issue #21 and some other tweaks'" [master 79ca184] Merge from bitbucket mirror: 'gpiancastelli - Fix for issue #21 and some other tweaks' 6 files changed, 78 insertions(+), 63 deletions(-) ~/git/python_koans $ git push origin master Or just use hg-git? The github developers have actually published a plugin for automatic mirroring: http://hg-git.github.com I haven’t used it because at the time I tried it a couple of years ago I was having problems getting all the parts to play nice with each other. Probably works fine now though..

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  • Does Entity Framework 4 not support property automatic lazy loading for model-first entities?

    - by KallDrexx
    All references that I find for lazy loading say it's possible but they all mention POCOs and that's it. I am using EF4 with the model-first methodology. In my model diagram I have a Project table and a UserObject table, with a 1 to many relationship between them. However, in code, when I have a valid UserObject and I attempt to get the project performing: Project prj = userobj.Project. Unfortunately, this doesn't work as it claims that UserObject.Project is null. It seems like I have to explicitly load the Project object via calling UserObject.ProjectReference.Load() prior to calling .Project. Is there any way for this to occur automatically when I access the .Project property?

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  • How can I implement lazy loading on a page with 500+ images?

    - by Fedor
    I basically have a booking engine unit results page which must show 40 units and per each unit there's 1 large image of the first thumbnail and an X number of accompanying thumbnail images. I've been using the jquery lazy load plugin, but it's not thorough enough ( I'm invoking it on DOM Ready ), plus it doesn't really work in IE ( 50% of the clients use IE so it's a big issue ). What I think I really need to do is not really spit out the image but a fake element such as a span, and possibly modify my code such that if the user views the span, render it into an image element. <span src="/images/foo.gif"> The booking engine relies on JS so I think I might be forced to just rely on ajaxifying all the thumbnails and have event handlers on window scroll, etc in order for the page to be "usable" and load at an average time ( 2-3 seconds instead of 5-30s on high speed DSL/Cable ). I'd appreciate any examples or ideas.

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  • Lazy loading? Better avoiding it?

    - by Charlie Pigarelli
    I just read about this design pattern: Lazy Load. And, since in the application i'm working on i have all the classes in one folder, i was wondering if this pattern could just make me avoiding the include() function for every class. I mean: It's nice to know that if i forgot to include a class, PHP, before falling into an error, trough an __autoload() function try to get it. But is it fine enough to just don't care about including classes and let PHP do it by your own every time? Or we should write __autoload() just in case it is needed?

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  • What is the best way to lazy load doubleclick ads that use document.write?

    - by user560585
    Ads requested through via doubleclick often get served from an ad provider network that returns javascript that in turn performs document.write to place ads in the page. The use of document.write requires that the document be open, implying that the page hasn't reached document.complete. This gets in the way of deferring or lazy loading ad content. Putting such code at page bottom is helpful but doesn't do enough to lower all-important "page-loaded" time. Are "friendly iframes" the best we have? Is there any other alternative such as a clever way to override document.write?

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  • How can I make a WPF TreeView data binding lazy and asynchronous?

    - by pauldoo
    I am learning how to use data binding in WPF for a TreeView. I am procedurally creating the Binding object, setting Source, Path, and Converter properties to point to my own classes. I can even go as far as setting IsAsync and I can see the GUI update asynchronously when I explore the tree. So far so good! My problem is that WPF eagerly evaluates parts of the tree prior to them being expanded in the GUI. If left long enough this would result in the entire tree being evaluated (well actually in this example my tree is infinite, but you get the idea). I would like the tree only be evaluated on demand as the user expands the nodes. Is this possible using the existing asynchronous data binding stuff in the WPF? As an aside I have not figured out how ObjectDataProvider relates to this task. My XAML code contains only a single TreeView object, and my C# code is: public partial class Window1 : Window { public Window1() { InitializeComponent(); treeView.Items.Add( CreateItem(2) ); } static TreeViewItem CreateItem(int number) { TreeViewItem item = new TreeViewItem(); item.Header = number; Binding b = new Binding(); b.Converter = new MyConverter(); b.Source = new MyDataProvider(number); b.Path = new PropertyPath("Value"); b.IsAsync = true; item.SetBinding(TreeView.ItemsSourceProperty, b); return item; } class MyDataProvider { readonly int m_value; public MyDataProvider(int value) { m_value = value; } public int[] Value { get { // Sleep to mimick a costly operation that should not hang the UI System.Threading.Thread.Sleep(2000); System.Diagnostics.Debug.Write(string.Format("Evaluated for {0}\n", m_value)); return new int[] { m_value * 2, m_value + 1, }; } } } class MyConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { // Convert the double to an int. int[] values = (int[])value; IList<TreeViewItem> result = new List<TreeViewItem>(); foreach (int i in values) { result.Add(CreateItem(i)); } return result; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new InvalidOperationException("Not implemented."); } } } Note: I have previously managed to do lazy evaluation of the tree nodes by adding WPF event handlers and directly adding items when the event handlers are triggered. I'm trying to move away from that and use data binding instead (which I understand is more in spirit with "the WPF way").

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  • Problem using Lazy<T> from within a generic abstract class

    - by James Black
    I have a generic class that all my DAO classes derive from, which is defined below. I also have a base class for all my entities, but that is not generic. The method GetIdOrSave is going to be a different type than how I defined SabaAbstractDAO, as I am trying to get the primary key to fulfill the foreign key relationships, so this function goes out to either get the primary key or save the entity and then get the primary key. The last code snippet has a solution on how it will work if I get rid of the generic part, so I think this can be solved by using variance, but I can't figure out how to write an interface that will compile. public abstract class SabaAbstractDAO<T> { ... public K GetIdOrSave<K>(K item, Lazy<SabaAbstractDAO<BaseModel>> lazyitemdao) where K : BaseModel { if (item != null && item.Id.IsNull()) { var itemdao = lazyitemdao.Value; item.Id = itemdao.retrieveID(item); if (item.Id.IsNull()) { return itemdao.SaveData(item); } } return item; } } I am getting this error, when I try to compile: Argument 2: cannot convert from 'System.Lazy<ORNL.HRD.LMS.Dao.SabaCourseDAO>' to 'System.Lazy<ORNL.HRD.LMS.Dao.SabaAbstractDAO<ORNL.HRD.LMS.Models.BaseModel>>' I am trying to call it this way: GetIdOrSave(input.OfferingTemplate, new Lazy<SabaCourseDAO>( () => { return new SabaCourseDAO() { Dao = Dao }; }) ); If I change the definition to this, it works. public K GetIdOrSave<K>(K item, Lazy<SabaCourseDAO> lazyitemdao) where K : BaseModel { So, how can I get this to compile using variance (if needed) and generics, so I can have a very general method that will only work with BaseModel and AbstractDAO<BaseModel>? I expect I should only need to make the change in the method and perhaps abstract class definition, the usage should be fine.

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  • LINQ to SQL: On load processing of lazy loaded associations

    - by Matt Holmes
    If I have an object that lazy loads an association with very large objects, is there a way I can do processing at the time the lazy load occurs? I thought I could use AssociateWith or LoadWith from DataLoadOptions, but there are very, very specific restrictions on what you can do in those. Basically I need to be notified when an EntitySet< decides it's time to load the associated object, so I can catch that event and do some processing on the loaded object. I don't want to simply walk through the EntitySet when I load the parent object, because that will force all the lazy loaded items to load (defeating the purpose of lazy loading entirely).

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  • To be a lazy developer or not to be a lazy developer?

    - by JamesStuddart
    Am I a lazy developer? Is it being lazy to use automated tools, such as code generators and such? Now, I could, if I had to, create all the data layers and entities I needed, but I choose to use CodeSmith to generate my datalayers and entities. I also use Resharper and I would say it fights with MSDeploy as to which gets installed first after Visual Studio. Again if I had to, I could code without it, but prefer not to. Both these tools from my point of view are no brainers as they improve output massively. But is this lazy? I'm sure there are purists out there that would say everything should be wirtten by you so you know what everything is doing, but if you can read through the code and see what is happening is that ok? So am I being lazy or am I just using all the cards in my hand?

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  • Java Hibernate Lazy=false

    - by Noor
    When setting Lazy=false, then hibernate will automatically loads the objects into the required sets e.g. <set name="Options" table="ATTRIBUTEOPTION" inverse="false" cascade="all" lazy="false"> <key> <column name="ATTRIBUTEID" /> </key> <one-to-many class="com.BiddingSystem.Models.AttributeOption" /> </set> but if in my xml mapping, I place lazy=true and in some place in my application i decide that i want to load all attribute options, should i do it manually, or is there a technique which lets tells hibernate that now i want to set lazy=false??

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  • WPF: Reloading app parts to handle persistence as well as memory management.

    - by Ingó Vals
    I created a app using Microsoft's WPF. It mostly handles data reading and input as well as associating relations between data within specific parameters. As a total beginner I made some bad design decision ( not so much decisions as using the first thing I got to work ) but now understanding WPF better I'm getting the urge to refactor my code with better design principles. I had several problems but I guess each deserves it's own question for clarity. Here I'm asking for proper ways to handle the data itself. In the original I wrapped each row in a object when fetched from database ( using LINQ to SQL ) somewhat like Active Record just not active or persistence (each app instance had it's own data handling part). The app has subunits handling different aspects. However as it was setup it loaded everything when started. This creates several problems, for example often it wouldn't be neccesary to load a part unless we were specifically going to work with that part so I wan't some form of lazy loading. Also there was problem with inner persistance because you might create a new object/row in one aspect and perhaps set relation between it and different object but the new object wouldn't appear until the program was restarted. Persistance between instances of the app won't be huge problem because of the small amount of people using the program. While I could solve this now using dirty tricks I would rather refactor the program and do it elegantly, Now the question is how. I know there are several ways and a few come to mind: 1) Each aspect of the program is it's own UserControl that get's reloaded/instanced everytime you navigate to it. This ensures you only load up the data you need and you get some persistancy. DB server located on same LAN and tables are small so that shouldn't be a big problem. Minor drawback is that you would have to remember the state of each aspect so you wouldn't always start at beginners square. 2) Having a ViewModel type object at the base level of the app with lazy loading and some kind of timeout. I would then propegate this object down the visual tree to ensure every aspect is getting it's data from the same instance 3) Semi active record data layer with static load methods. 4) Some other idea What in your opinion is the most practical way in WPF, what does MVVM assume?

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  • How to fix a NHibernate lazy loading error "no session or session was closed"?

    - by MCardinale
    I'm developing a website with ASP.NET MVC, NHibernate and Fluent Hibernate and getting the error "no session or session was closed" when I try to access a child object. These are my domain classes: public class ImageGallery { public virtual int Id { get; set; } public virtual string Title { get; set; } public virtual IList<Image> Images { get; set; } } public class Image { public virtual int Id { get; set; } public virtual ImageGallery ImageGallery { get; set; } public virtual string File { get; set; } } These are my maps: public class ImageGalleryMap:ClassMap<ImageGallery> { public ImageGalleryMap() { Id(x => x.Id); Map(x => x.Title); HasMany(x => x.Images); } } public class ImageMap:ClassMap<Image> { public ImageMap() { Id(x => x.Id); References(x => x.ImageGallery); Map(x => x.File); } } And this is my Session Factory helper class: public class NHibernateSessionFactory { private static ISessionFactory _sessionFactory; private static ISessionFactory SessionFactory { get { if(_sessionFactory == null) { _sessionFactory = Fluently.Configure() .Database(MySQLConfiguration.Standard.ConnectionString(MyConnString)) .Mappings(m => m.FluentMappings.AddFromAssemblyOf<ImageGalleryMap>()) .ExposeConfiguration(c => c.Properties.Add("hbm2ddl.keywords", "none")) .BuildSessionFactory(); } return _sessionFactory; } } public static ISession OpenSession() { return SessionFactory.OpenSession(); } } Everything works fine, when I get ImageGallery from database using this code: IImageGalleryRepository igr = new ImageGalleryRepository(); ImageGallery ig = igr.GetById(1); But, when I try to access the Image child object with this code string imageFile = ig.Images[1].File; I get this error: Initializing[Entities.ImageGallery#1]-failed to lazily initialize a collection of role: Entities.ImageGallery.Images, no session or session was closed Someone know how can I fix this? Thank you very much!

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  • Entity Framework 4 relationship management in POCO Templates - More lazy than FixupCollection?

    - by Joe Wood
    I've been taking a look at EF4 POCO templates in beta 2. The FixupCollection looks fine for maintaining the model correctness after updating the relationship collection property (i.e. product.Orders it would set the order.Product reference ). But what about support for handling the scenario when some of those Order objects are removed from the context? The use-case of maintaining cascading deletes in the in-memory model. The old Typed DataSet model used to do this by performing the query through the container to derive the relationship results. Like the DataSet, this would require a reference to the ObjectContext inside the entity class so that it could query the top-level Order collection. Better support for Separation of Concerns in the ObjectContext would be required. It looks like EF is not suited to this use-case that DataSets did out of the box.... am I right?

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  • Entity Framework in n-layered application - Lazy loading vs. Eager loading patterns

    - by Marconline
    Hi all. This questions doesn't let me sleep as it's since one year I'm trying to find a solution but... still nothing happened in my mind. Probably you can help me, because I think this is a very common issue. I've a n-layered application: presentation layer, business logic layer, model layer. Suppose for simplicity that my application contains, in the presentation layer, a form that allows a user to search for a customer. Now the user fills the filters through the UI and clicks a button. Something happens and the request arrives to presentation layer to a method like CustomerSearch(CustomerFilter myFilter). This business logic layer now keeps it simple: creates a query on the model and gets back results. Now the question: how do you face the problem of loading data? I mean business logic layer doesn't know that that particular method will be invoked just by that form. So I think that it doesn't know if the requesting form needs just the Customer objects back or the Customer objects with the linked Order entities. I try to explain better: our form just wants to list Customers searching by surname. It has nothing to do with orders. So the business logic query will be something like: (from c in ctx.CustomerSet where c.Name.Contains(strQry) select c).ToList(); now this is working correctly. Two days later your boss asks you to add a form that let you search for customers like the other and you need to show the total count of orders created by each customer. Now I'd like to reuse that query and add the piece of logic that attach (includes) orders and gets back that. How would you front this request? Here is the best (I think) idea I had since now. I'd like to hear from you: my CustomerSearch method in BLL doesn't create the query directly but passes through private extension methods that compose the ObjectQuery like: private ObjectQuery<Customer> SearchCustomers(this ObjectQuery<Customer> qry, CustomerFilter myFilter) and private ObjectQuery<Customer> IncludeOrders(this ObjectQuery<Customer> qry) but this doesn't convince me as it seems too complex. Thanks, Marco

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