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• Argument exception after trying to use TryGetObjectByKey

  - by Rickjaah

  Hi, EDIT: Somethings wrong.... I have to use objectContext.Frontpages.ToArray() before I can use TryGetObjectByEntityKey(). Any ideas anyone? I'm trying to retrieve an object from my database using entity (framework 4) When I use the following code it gives an ArgumentException: An item with the same key has already been added. if (databaseContext.TryGetObjectByKey(entityKey, out result)) { return (result != null && result is TEntityObject) ? result as TEntityObject : null; } else { return null; } When I check the objectContext, I see the entities, but only if I enumerate the specific list of entities manually using VS2010, it works. What am I missing? Do I have to do something else before i can get the item from the database? I searched google, but could not find any results, the same for the msdn library EDIT: Still working on this.... It's a weird problem. I retrieve a value, but get an error that says a duplicate item exists. STACKTRACE: [ArgumentException: An item with the same key has already been added.] System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +52 System.Collections.Generic.Dictionary2.Insert(TKey key, TValue value, Boolean add) +9549131 System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.LoadRelationshipTypes() +661 System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.LoadTypesFromAssembly() +17 System.Data.Metadata.Edm.ObjectItemAssemblyLoader.Load() +25 System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.Load() +4 System.Data.Metadata.Edm.AssemblyCache.LoadAssembly(Assembly assembly, Boolean loadReferencedAssemblies, ObjectItemLoadingSessionData loadingData) +160 System.Data.Metadata.Edm.AssemblyCache.LoadAssembly(Assembly assembly, Boolean loadReferencedAssemblies, KnownAssembliesSet knownAssemblies, EdmItemCollection edmItemCollection, Action1 logLoadMessage, Object& loaderCookie, Dictionary2& typesInLoading, List1& errors) +166 System.Data.Metadata.Edm.ObjectItemCollection.LoadAssemblyFromCache(ObjectItemCollection objectItemCollection, Assembly assembly, Boolean loadReferencedAssemblies, EdmItemCollection edmItemCollection, Action`1 logLoadMessage) +316 System.Data.Metadata.Edm.MetadataWorkspace.ImplicitLoadAssemblyForType(Type type, Assembly callingAssembly) +306 System.Data.Metadata.Edm.MetadataWorkspace.ImplicitLoadFromEntityType(EntityType type, Assembly callingAssembly) +109 System.Data.Objects.ObjectContext.TryGetObjectByKey(EntityKey key, Object& value) +288 EDIT: Lazy loading is set to true. EDIT: Somethings wrong.... I have to use objectContext.Frontpages.ToArray() before I can use TryGetObjectByEntityKey(). Any ideas anyone?

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• A list of Entity Framework providers for various databases

  - by Robert Koritnik

  Which providers are there and your experience using them I would like to know about all possible native .net Framework Entity Framework providers that are out there as well as their limitations compared to the default Linq2Entities (from MS for MS SQL). If there are more for the same database even better. Tell me and I'll be updating this post with this list. Feel free to add additional providers directly into this post or provide an answer and others (including me) will add it to the list. Entity Framework 1 Microsoft SQL Server Standard/Enterprise/Express Linq 2 Entities - Microsoft SQL Server connector DataDirect ADO.NET Data Providers Microsoft SQL Server CE (Compact Edition) Any provider? MySQL MySQL Connector (since version 6.0) - I've read about issues when using Skip(), Take() and Sort() in the same expression tree - everyone welcome to input their experience/knowledge regarding this. (NOTE: MySQL Connector/NET Visual Studio Integration is not supported in the Express Editions of Visual Studio, meaning you won't be able to view MySQL databases in the Database explorer window or add a MySQL data source via Visual Studio wizard dialog boxes. Some users may find that this limits their ability to use Entity Framework and MySQL within Visual Studio Express). Devart dotConnect for MySQL - similar issues to MySql's connector as I've read and both try to blame MS for it [these issues are supposed to be solved] SQLite Devart dotConnect for SQLite System.Data.SQLite PostgreSQL Devart dotConnect for PostgreSQL Npgsql Oracle Devart dotConnect for Oracle Sample Entity Framework Provider for Oracle - community effort project DataDirect ADO.NET Data Providers DB2 IBM Data Server Provider has EF support. Here are some limitations. DataDirect ADO.NET Data Providers Sybase Sybase iAnywhere DataDirect ADO.NET Data Providers Informix IBM Data Server Provider supports Informix Firebird ADO.NET Data Provider with EF support Provider Wrappers Tracing and Caching Providers for EF Entity Framework 4 (beta) Microsoft SQL Server Microsoft's Linq to Entities 4 - shipped with .net 4.0 and Visual Studio 2010; so far the only provider for EF4 MySQL Devart dotConnect for MySQL SQLite Devart dotConnect for SQLite PostgreSQL Devart dotConnect for PostgreSQL Oracle Devart dotConnect for Oracle

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• "The name 'WithTable' does not exist in the current context" using Fluent NHibernate

  - by Byron Sommardahl

  Might be a really easy problem to fix, but it the solution is eluding me! I'm using Fluent NHibernate 1.0 RTM (and using NHibernate bins that ships with it). I'm trying to map my entities and cannot use the WithTable() method. It's not available in Intelligence and VS doesn't suggest any namespaces to reference. Here's my code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using GeoCodeThe.Net.Domain.Entities; using FluentNHibernate.Mapping; namespace GeoCodeThe.Net.Domain.Mappings { class CategoryMap: ClassMap<ICategory> { public CategoryMap() { WithTable("Categories"); // <----- Compile error: The name 'WithTable' does not exist in the current context Id(x => x.Id); Map(x => x.Name); Map(x => x.Tags); } } My bin folder has: Antlr3.Runtime.dll Castle.Core.dll Castle.DynamicProxy2.dll FluentNHibernate.dll Iesi.Collections.dll log4net.dll NHibernate.ByteCode.Castle.dll NHibernate.dll FluentNHibernate.pdb Castle.Core.xml Castle.DynamicProxy2.xml FluentNHibernate.xml Iesi.Collections.xml log4net.xml NHibernate.ByteCode.Castle.xml NHibernate.xml Any clue what I'm missing? Let me know if you need any more clarification.

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• Problem with custom Equality in Entity Framework

  - by Shimmy

  Hello! I am using Entity Framework in my application. I implemented with the partial class of an entity the IEquatable<T> interface: Partial Class Address : Implements IEquatable(Of Address) 'Other part generated Public Overloads Function Equals(ByVal other As Address) As Boolean _ Implements System.IEquatable(Of Address).Equals If ReferenceEquals(Me, other) Then Return True Return AddressId = other.AddressId End Function Public Overrides Function Equals(ByVal obj As Object) As Boolean If obj Is Nothing Then Return MyBase.Equals(obj) If TypeOf obj Is Address Then Return Equals(DirectCast(obj, Address)) Else Return False End Function Public Overrides Function GetHashCode() As Integer Return AddressId.GetHashCode End Function End Class Now in my code I use it this way: Sub Main() Using e As New CompleteKitchenEntities Dim job = e.Job.FirstOrDefault Dim address As New Address() job.Addresses.Add(address) Dim contains1 = job.Addresses.Contains(address) 'True e.SaveChanges() Dim contains2 = job.Addresses.Contains(address) 'False 'The problem is that I can't remove it: Dim removed = job.Addresses.Remoeve(address) 'False End Using End Sub Note (I checked in the debugger visualizer) that the EntityCollection class stores its entities in HashSet so it has to do with the GetHashCode function, I want it to depend on the ID so entities are compared by their IDs. Please help me find what's wrong in the GetHashCode function (by ID) and what can I change to make it work. Thanks a lot.

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• WPF Control validation

  - by Jon

  Hi all, I'm developing a WPF GUI framework and have had bad experiences with two way binding and lots of un-needed events being fire(mainly in Flex) so I have gone down the route of having bindings (string that represent object paths) in my controls. When a view is requested to be displayed the controller loads the view, and gets the needed entities (using the bindings) from the DB and populates the controls with the correct values. This has a number of advantages i.e. lazy loading, default undo behaviour etc. When the data in the view needs to be saved the view is passed back to the controller again which basically does the reserve i.e. re-populates the entities from the view if values have changed. However, I have run into problems when I try and validate the components. Each entity has attributes on its properties that define validation rules which the controller can access easily and validate the data from the view against it. The actual validation of data is fine. The problem comes when I want the GUI control to display error validation information. It I try changing the style I get errors saying styles cannot be changed once in use. Is the a way in c# to fire off the normal WPF validation mechanism and just proved it with the validaiton errors the controller has found? Thanks in advance Jon

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• Map NHibernate entity to multiple tables based on parent

  - by Programming Hero

  I'm creating a domain model where entities often (but not always) have a member of type ActionLog. ActionLog is a simple class which allows for an audit trail of actions being performed on an instance. Each action is recorded as an ActionLogEntry instance. ActionLog is implemented (approximately) as follows: public class ActionLog { public IEnumerable<ActionLogEntry> Entries { get { return EntriesCollection; } } protected ICollection<ActionLogEntry> EntriesCollection { get; set; } public void AddAction(string action) { // Append to entries collection. } } What I would like is to re-use this class amongst my entities and have the entries map to different tables based on which class they are logged against. For example: public class Customer { public ActionLog Actions { get; protected set; } } public class Order { public ActionLog Actions { get; protected set; } } This design is suitable for me in the application, however I can't see a clear way to map this scenario to a database with NHibernate. I typically use Fluent NHibernate for my configuration, but I'm happy to accept answers in more general HBM xml.

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• Castle MonoRail ARDataBind trying to bind to non-existent row

  - by dave thieben

  I have a shopping cart application running on MonoRail and using Castle ActiveRecord/NHibernate, and there is a ShoppingCart table and a ShoppingCartItems table, which are mapped to entities. Here's the scenario: a user adds things to the shopping cart, say 5 items, and goes to view the cart. The cart shows all 5 items. the user duplicates the tab/window and gets another tab of the same cart (call it tab B). the user removes an item from the cart, so now there are 4 items in tab B, but in the original tab A, there are still 5 items. the user goes back to tab A, and updates something in the cart and clicks the "update" button which submits the changes. my MonoRail action tries to do an ARDataBind on ShoppingCartItems using the data from the view, which includes all 5 items. when it gets to the item that the user deleted from tab B, it throws a "No row with the given identifier exists" for that item. I can't figure out if there is a way to have it not bind that row, return null, return new instance, etc.? there is an AutoLoadBehavior parameter on the ARDataBind attribute, but that appears to only affect loading of child entities, and not the root entity. regardless of which option I choose, I get the exception before control even enters the action method (except AutoLoadBehavior.Never, but that doesn't really help me). instead, I have code that calls Request.ObtainParamsNode() to pull the form nodes and parse them manually into objects, and ignores the ones that no longer exist. is there a better way? thanks.

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• Deleting JPA entity containing @CollectionOfElements throws ConstraintViolationException

  - by Lyle

  I'm trying to delete entities which contain lists of Integer, and I'm getting ConstraintViolationExceptions because of the foreign key on the table generated to hold the integers. It appears that the delete isn't cascading to the mapped collection. I've done quite a bit of searching, but all of the examples I've seen on how to accomplish this are in reference to a mapped collection of other entities which can be annotated; here I'm just storing a list of Integer. Here is the relevant excerpt from the class I'm storing: @Entity @Table(name="CHANGE_IDS") @GenericGenerator( name = "CHANGE_ID_GEN", strategy = "org.hibernate.id.enhanced.SequenceStyleGenerator", parameters = { @Parameter(name="sequence_name", value="course_changes_seq"), @Parameter(name="increment_size", value="5000"), @Parameter(name=" optimizer", value="pooled") } ) @NamedQueries ({ @NamedQuery( name="Changes.getByStatus", query= "SELECT c " + "FROM DChanges c " + "WHERE c.status = :status "), @NamedQuery( name="Changes.deleteByStatus", query= "DELETE " + "FROM Changes c " + "WHERE c.status = :status ") }) public class Changes { @Id @GeneratedValue(generator="CHANGE_ID_GEN") @Column(name = "ID") private final long id; @Enumerated(EnumType.STRING) @Column(name = "STATUS", length = 20, nullable = false) private final Status status; @Column(name="DOC_ID") @org.hibernate.annotations.CollectionOfElements @org.hibernate.annotations.IndexColumn(name="DOC_ID_ORDER") private List<Integer> docIds; } I'm deleting the Changes objects using a @NamedQuery: final Query deleteQuery = this.entityManager.createNamedQuery("Changes.deleteByStatus"); deleteQuery.setParameter("status", Status.POST_FLIP); final int deleted = deleteQuery.executeUpdate(); this.logger.info("Deleted " + deleted + " POST_FLIP Changes");

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• Using YQL multi-query & XPath to parse HTML, how to escape nested quotes?

  - by Tivac

  The title is more complicated than it has to be, here's the problem query. SELECT * FROM query.multi WHERE queries=" SELECT * FROM html WHERE url='http://www.stumbleupon.com/url/http://www.guildwars2.com' AND xpath='//li[@class=\"listLi\"]/div[@class=\"views\"]/a/span'; SELECT * FROM xml WHERE url='http://services.digg.com/1.0/endpoint?method=story.getAll&link=http://www.guildwars2.com'; SELECT * FROM json WHERE url='http://api.tweetmeme.com/url_info.json?url=http://www.guildwars2.com'; SELECT * FROM xml WHERE url='http://api.facebook.com/restserver.php?method=links.getStats&urls=http://www.guildwars2.com'; SELECT * FROM json WHERE url='http://www.reddit.com/button_info.json?url=http://www.guildwars2.com'" Specifically this line, xpath='//li[@class=\"listLi\"]/div[@class=\"views\"]/a/span' It's problematic because of the quoting, I have to nest them three levels deep and I've run out of quote characters to use. I've tried the following variations without success: //no attribute quoting xpath='//li[@class=listLi]/div[@class=views]/a/span' //try to quote attribute w/ backslash & single quote xpath='//li[@class=\'listLi\']/div[@class=\'views\']/a/span' //try to quote attribute w/ backslash & double quote xpath='//li[@class=\"listLi\"]/div[@class=\"views\"]/a/span' //try to quote attribute with double single quotes, like SQL xpath='//li[@class=''listLi'']/div[@class=''views'']/a/span' //try to quote attribute with double double quotes, like SQL xpath='//li[@class=""listLi""]/div[@class=""views""]/a/span' //try to quote attribute with quote entities xpath='//li[@class=&quot;listLi&quot;]/div[@class=&quot;views&quot;]/a/span' //try to surround XPath with backslash & double quote xpath=\"//li[@class='listLi']/div[@class='views']/a/span\" //try to surround XPath with double double quote xpath=""//li[@class='listLi']/div[@class='views']/a/span"" All without success. I don't see much out there about escaping XPath strings but everything I've found seems to be variations on using concat (which won't help because neither ' nor " are available) or html entities. Not using quotes for the attributes doesn't throw an error but fails because it's not the actual XPath string I need. I don't see anything in the YQL docs about how to handle escaping. I'm aware of how edge-casey this is but was hoping they'd have some sort of escaping guide.

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• How do you determine subtype of an entity using Inheritance with Entity Framework 4?

  - by KallDrexx

  I am just starting to use the Entity Framework 4 for the first time ever. So far I am liking it but I am a bit confused on how to correctly do inheritance. I am doing a model-first approach, and I have my Person entity with two subtype entities, Employee and Client. EF is correctly using the table per type approach, however I can't seem to figure out how to determine what type of a Person a specific object is. For example, if I do something like var people = from p in entities.Person select p; return people.ToList<Person>(); In my list that I form from this, all I care about is the Id field so i don't want to actually query all the subtype tables (this is a webpage list with links, so all I need is the name and the Id, all in the Persons table). However, I want to form different lists using this one query, one for each type of person (so one list for Clients and another for Employees). The issue is if I have a Person entity, I can't see any way to determine if that entity is a Client or an Employee without querying the Client or Employee tables directly. How can I easily determine the subtype of an entity without performing a bunch of additional database queries?

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• REST application, Transactions, Cache drop

  - by Julian Davchev

  Hi, I am building REST API in php with memcache layer on top for caching all resources. After some reading experience it turns out it's best when documents are as simple as posible...mainly due to dropping cache sequences. So if there is 'building','room' entities for the 'room' document I would only place the id of the 'building' and not the whole data of it. Then on api client side I would merge data as needed. Problem becomes when I need to update/insert (most cases more than one table). I update one resource but on second update system fails or whatever and there becomes database inconsistancies. I see several solutions: 1. Implement rest transactions which I find wrong and complex as idea is to be stateless and easy. 2. On update/insert actions I pass more complex data (not single entities) so I can force transactions on API level. But this will make it weird that your GET document structure is same as PUT document structure. And again somehow make drop sequences complex. Any pointers are more than welcome. Cheers,

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• ORM model and DAO in my particular case

  - by EugeneP

  I have the DB structure as follows: table STUDENT (say, id, surname, etc) table STUDENT_PROPERTIES (say, name_of_the_property:char, value_of_the_property:char, student_id:FK) table COURSE (id, name, statusofcourse_id) table STATUSOFCOURSE (id, name_of_status:char ('active','inactive','suspended' etc)) table STUDENT_COURSE (student_id,course_id,statusofcourse_id) Let's try to pick up domain objects in my database: Student and Course are main entities. Student has a list of courses he attends, also he has a list of properties, that is all for this student. Next, Course entitity. It may contain a list of students that attend it. But in fact, the whole structure looks like this: the starting point is Student, with it's PK we can look a list of his properties, then we look into the STUDENT_COURSE and extract both FK of the Course entity and also the Status of the combination, it would look like "Student named bla bla, with all his properties, attends math and the status of it is "ACTIVE". now, quotation 1) Each DAO instance is responsible for one primary domain object or entity. If a domain object has an independent lifecycle, it should have its own DAO. 2) The DAO is responsible for creations, reads (by primary key), updates, and deletions -- that is, CRUD -- on the domain object. Now, first question is What are entities in my case? Student, Course, Student_Course, Status = all except for StudentProperties? Do I have to create a separate DAO for every object?

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• Entity Framework Update Error in ASP.NET Mvc with related entity

  - by Barry

  I have run into a problem which have searched and tried everything i can to find a solution but to no avail. I am using the same repository and context throughout the process I have a booking entity and a userExtension Entity Below is my image i then get my form collection back from my page and create a new booking public ActionResult Create(FormCollection collection) { Booking toBooking = new Booking(); i then do some validation and property assignment and find an associated BidInstance toBooking.BidInstance = bid; i have checked and the bid is not null. finally i get the user extension file from the Current IPRINCIPAL USER as below UserExtension loggedInUser = m_BookingRepository.GetBookingCurrentUser(User); toBooking.UserExtension = loggedInUser; The Code to do the getUserExtension is : public UserExtension GetBookingCurrentUser(IPrincipal currentUser) { var user = (from u in Context.aspnet_Users .Include("UserExtension") where u.UserName == currentUser.Identity.Name select u).FirstOrDefault(); if (user != null) { var userextension = (from u in Context.UserExtension.Include("aspnet_Users") where u.aspnet_Users.UserId == user.UserId select u).FirstOrDefault(); return userextension; } else{ return null; } } It returns the userextension fine and assigns it fine. i originally used the aspnet_users but encountered this problem so tried to change it to the extension entity. as soon as i call the : Context.AddToBooking(booking); Context.SaveChanges(); i get the following exception and im completely baffled by how to fix it Entities in 'FutureFlyersEntityModel.Booking' participate in the 'FK_Booking_UserExtension' relationship. 0 related 'UserExtension' were found. 1 'UserExtension' is expected. then the final error that comes to the front end is: Metadata information for the relationship 'FutureFlyersModel.FK_Booking_BidInstance' could not be retrieved. Make sure that the EdmRelationshipAttribute for the relationship has been defined in the assembly. Parameter name: relationshipName.. But both the related entities are set in the booking entity passed thruogh PLEASE HELP Im at wits end with this

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• Problem with custom Equality and GetHashCode in a mutable object

  - by Shimmy

  Hello! I am using Entity Framework in my application. I implemented with the partial class of an entity the IEquatable<T> interface: Partial Class Address : Implements IEquatable(Of Address) 'Other part generated Public Overloads Function Equals(ByVal other As Address) As Boolean _ Implements System.IEquatable(Of Address).Equals If ReferenceEquals(Me, other) Then Return True Return AddressId = other.AddressId End Function Public Overrides Function Equals(ByVal obj As Object) As Boolean If obj Is Nothing Then Return MyBase.Equals(obj) If TypeOf obj Is Address Then Return Equals(DirectCast(obj, Address)) Else Return False End Function Public Overrides Function GetHashCode() As Integer Return AddressId.GetHashCode End Function End Class Now in my code I use it this way: Sub Main() Using e As New CompleteKitchenEntities Dim job = e.Job.FirstOrDefault Dim address As New Address() job.Addresses.Add(address) Dim contains1 = job.Addresses.Contains(address) 'True e.SaveChanges() Dim contains2 = job.Addresses.Contains(address) 'False 'The problem is that I can't remove it: Dim removed = job.Addresses.Remoeve(address) 'False End Using End Sub Note (I checked in the debugger visualizer) that the EntityCollection class stores its entities in HashSet so it has to do with the GetHashCode function, I want it to depend on the ID so entities are compared by their IDs. The problem is that when I hit save, the ID changes from 0 to its db value. So the question is how can I have an equatable object, being properly hashed. Please help me find what's wrong in the GetHashCode function (by ID) and what can I change to make it work. Thanks a lot.

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• Persisting complex data between postbacks in ASP.NET MVC

  - by Robert Wagner

  I'm developing an ASP.NET MVC 2 application that connects to some services to do data retrieval and update. The services require that I provide the original entity along with the updated entity when updating data. This is so it can do change tracking and optimistic concurrency. The services cannot be changed. My problem is that I need to somehow store the original entity between postbacks. In WebForms, I would have used ViewState, but from what I have read, that is out for MVC. The original values do not have to be tamper proof as the services treat them as untrusted. The entities would be (max) 1k and it is an intranet app. The options I have come up are: Session - Ruled out - Store the entity in the Session, but I don't like this idea as there are no plans to share session between URL - Ruled out - Data is too big HiddenField - Store the serialized entity in a hidden field, perhaps with encryption/encoding HiddenVersion - The entities have a (SQL) version field on them, which I could put into a hidden field. Then on a save I get "original" entity from the services and compare the versions, doing my own optimistic concurrency. Cookies - Like 3 or 4, but using a cookie instead of a hidden field I'm leaning towards option 4, although 3 would be simpler. Are these valid options or am I going down the wrong track? Is there a better way of doing this?

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• parameterized doctype in xsl:stylesheet

  - by Flavius

  How could I inject a --stringparam (xsltproc) into the DOCTYPE of a XSL stylesheet? The --stringparam is specified from the command line. I have several books in docbook5 format I want to process with the same customization layer, each book having an unique identifier, here "demo", so I'm running something like xsltproc --stringparam course.name demo ... for each book. Obviously the parameter is not recognized as such, but as verbatim text, giving the error: warning: failed to load external entity "http://edu.yet-another-project.com/course/$(course.name)/entities.ent" Here it is how I've tried, which won't work: <?xml version='1.0'?> <!DOCTYPE stylesheet [ <!ENTITY % myent SYSTEM "http://edu.yet-another-project.com/course/$(course.name)/entities.ent"> %myent; ]> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> <!-- the docbook template used --> <xsl:import href="http://docbook.org/ns/docbook/xhtml/chunk.xsl"/> <!-- processor parameters --> <xsl:param name="html.stylesheet">default.css</xsl:param> <xsl:param name="use.id.as.filename">1</xsl:param> <xsl:param name="chunker.output.encoding">UTF-8</xsl:param> <xsl:param name="chunker.output.indent">yes</xsl:param> <xsl:param name="navig.graphics">1</xsl:param> <xsl:param name="generate.revhistory.link">1</xsl:param> <xsl:param name="admon.graphics">1</xsl:param> <!-- here more stuff --> </xsl:stylesheet> Ideas?

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• Entity Framework query

  - by carter-boater

  Hi all, I have a piece of code that I don't know how to improve it. I have two entities: EntityP and EntityC. EntityP is the parent of EntityC. It is 1 to many relationship. EntityP has a property depending on a property of all its attached EntityC. I need to load a list of EntityP with the property set correctly. So I wrote a piece of code to get the EntityP List first.It's called entityP_List. Then as I wrote below, I loop through the entityP_List and for each of them, I query the database with a "any" function which will eventually be translated to "NOT EXIST" sql query. The reason I use this is that I don't want to load all the attached entityC from database to memory, because I only need the aggregation value of their property. But the problem here is, the looping will query the databae many times, for each EntityP! So I am wondering if anybody can help me improve the code to query the database only once to get all the EntityP.IsAll_C_Complete set, without load EntityC to memory. foreach(EntityP p in entityP_List) { isAnyNotComoplete = entities.entityC.Any(c => c.IsComplete==false && c.parent.ID == p.ID); p.IsAll_C_Complete = !isAnyNotComoplete; } Thank you very much!

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• RESTfully Nesting Resource Routes with Single Identifiers

  - by Craig Walker

  In my Rails app I have a fairly standard has_many relationship between two entities. A Foo has zero or more Bars; a Bar belongs to exactly one Foo. Both Foo and Bar are identified by a single integer ID value. These values are unique across all of their respective instances. Bar is existence dependent on Foo: it makes no sense to have a Bar without a Foo. There's two ways to RESTfully references instances of these classes. Given a Foo.id of "100" and a Bar.id of "200": Reference each Foo and Bar through their own "top-level" URL routes, like so: /foo/100 /bar/200 Reference Bar as a nested resource through its instance of Foo: /foo/100 /foo/100/bar/200 I like the nested routes in #2 as it more closely represents the actual dependency relationship between the entities. However, it does seem to involve a lot of extra work for very little gain. Assuming that I know about a particular Bar, I don't need to be told about a particular Foo; I can derive that from the Bar itself. In fact, I probably should be validating the routed Foo everywhere I go (so that you couldn't do /foo/150/bar/200, assuming Bar 200 is not assigned to Foo 150). Ultimately, I don't see what this brings me. So, are there any other arguments for or against these two routing schemes?

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• Proper way to validate model in ASP.NET MVC 2 and ViewModel apporach

  - by adrin

  I am writing an ASP.NET MVC 2 application using NHibernate and repository pattern. I have an assembly that contains my model (business entities), moreover in my web project I want to use flattened objects (possibly with additional properties/logic) as ViewModels. These VMs contain UI-specific metadata (eg. DisplayAttribute used by Html.LabelFor() method). The problem is that I don't know how to implement validation so that I don't repeat myself throughout various tiers (specifically validation rules are written once in Model and propagated to ViewModel). I am using DataAnnotations on my ViewModel but this means no validation rules are imposed on the Model itself. One approach I am considering is deriving ViewModel objects from business entities adding new properties/overriding old ones, thus preserving validation metadata between the two however this is an ugly workaround. I have seen Automapper project which helps to map properties, but I am not sure if it can handle ASP.NET MVC 2 validation metadata properly. Is it difficult to use custom validation framework in asp.net mvc 2? Do you have any patterns that help to preserve DRY in regard to validation?

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• PHP DomDocument class unable access domnode

  - by turbod

  Hi. I dont parse this url: http://foldmunka.net $ch = curl_init("http://foldmunka.net"); //curl_setopt($ch, CURLOPT_NOBODY, true); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); //curl_setopt($ch, CURLOPT_HEADER, true); curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); //not necessary unless the file redirects (like the PHP example we're using here) $data = curl_exec($ch); $info = curl_getinfo($ch); curl_close($ch); clearstatcache(); if ($data === false) { echo 'cURL failed'; exit; } $dom = new DOMDocument(); $data = mb_convert_encoding($data, 'HTML-ENTITIES', "utf-8"); $data = preg_replace('/<\!\-\-\[if(.*)\]>/', '', $data); $data = str_replace('<![endif]-->', '', $data); $data = str_replace('<!--', '', $data); $data = str_replace('-->', '', $data); $data = preg_replace('@<script[^>]*?>.*?</script>@si', '', $data); $data = preg_replace('@<style[^>]*?>.*?</style>@si', '', $data); $data = mb_convert_encoding($data, 'HTML-ENTITIES', "utf-8"); @$dom->loadHTML($data); $els = $dom->getElementsByTagName('*'); foreach($els as $el){ print $el->nodeName." | ".$el->getAttribute('content')."<hr />"; if($el->getAttribute('title'))$el->nodeValue = $el->getAttribute('title')." ".$el->nodeValue; if($el->getAttribute('alt'))$el->nodeValue = $el->getAttribute('alt')." ".$el->nodeValue; print $el->nodeName." | ".$el->nodeValue."<hr />"; } I need the alt, title attributes and the simple text, but this page i cannot access the nodes within the body tag.

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• using Autofac in a multi-layered architecture

  - by Kamyar

  I'm fairly new to the DI/IoC concept and would like to use Autofac in a 3-layered ASP.NET Webforms application. UI layer: An ASP.NET webforms website. BLL: Business logic layer which calls the repositories on DAL. DAL: .EDMX file (Entity Model) and ObjectContext with Repository classes which abstract the CRUD operations for each entity. Entities: The POCO Entities. Persistence Ignorant. Generated by Microsoft's ADO.Net POCO Entity Generator. I have asked a more general question here. Basically, I'd like to create an obejctcontext per HttpContext in my DAL. But i don't want to add a reference to DAL in UI or access to HttpContext in DAL directly. I guess this is where IoC tools come to play. The answer to my previous question is a very good example of using Windsor Castle. I'd like to use Autofac as my IoC tool and Don't know how to achieve this. (How to access DAL in application_start to register the component while I don't want to reference it in my UI, what are the proper references to be able to use DAL component in BLL with Autofac, Should I register BLL as a component with Autofac too) Sorry folks for not providing an explicit question and requesting a kind of working example, But I'm very unfamiliar to the whole IoC concept and I don't think I can achieve it to use in my current time-limited project.

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• Maintaining state and data context between requests in ASP.NET + EF4

  - by Nick

  I have a EF4/ASP.NET web application that is structured to use POCOs and generic repositories, based essentially on this excellent article. The application is relatively sophisticated with one page that involves selection and linking of multiple entities to build up a complex user profile. This requires access to multiple entity types (20 or so) and associated repositories across multiple posts. When a repository is first accessed it uses the existing data context if exists, else it creates a new context. The problem is that if the lifetime of the context is only per-request (as suggested in the article) then you have to deal with multiple contexts and the complexity around detaching and attaching entities from contexts. My solution is to share the context between posts by creating a single View Model that includes all required repositories (initialised to share the same context) plus any associated data and store this model in a Session variable, retrieving from Session on subsequent page requests. Therefore maintaining the same context across all posts until the profile is saved. This works fine BUT I am concerned that I don't actually know exactly what is stored in the model session variable or more importantly the size of the Session variable. So two questions I suppose: firstly should I look for a better solution to handle the shared context across posts issue (any suggestions welcome)? And secondly what is actually stored in the Session when it includes a repository plus context? Any help appreciated!

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• WCF Data Services - neither .Expand or .LoadProperty seems to do what I need

  - by TomK

  I am building a school management app where they track student tardiness and absences. I've got three entities to help me in this. A Students entity (first name, last name, ID, etc.); a SystemAbsenceTypes entity with SystemAbsenceTypeID values for Late, Absent-with-Reason, Absent-without-Reason; and a cross-reference table called StudentAbsences (matching the student IDs with the absence-type ID, plus a date, and a Notes field). What I want to do is query my entities for a given student, and then add up the number of each kind of Absence, for a given date range. I prepare my currentStudent object without a problem, then I do this... Me.Data.LoadProperty(currentStudent, "StudentAbsences") 'Loads the cross-ref data lblDaysLate.Text = (From ab In currentStudent.StudentAbsences Where ab.SystemAbsenceTypes.SystemAbsenceTypeID = Common.enuStudentAbsenceTypes.Late).Count.ToString ...and this second line fails, complaining it has no value for an object. I presume the problem is that while it DOES see that there are (let's say) four absences for the currentStudent (ie, currentStudent.StudentAbsences.Count = 4) -- it can't yet "peer into" each one of the absences to look at its type. How do I use .Expand or .LoadProperty to make this happen? I tried fiddling with .LoadProperty but it doesn't take a two-level syntax like so... Data.LoadProperty(currentStudent,"StudentAbsences.SystemAbsenceTypeID") or the like. Is there some other technique?

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• ETL , Esper or Drools?

  - by geoaxis

  Hello, The question environment relates to JavaEE, Spring I am developing a system which can start and stop arbitrary TCP (or other) listeners for incoming messages. There could be a need to authenticate these messages. These messages need to be parsed and stored in some other entities. These entities model which fields they store. So for example if I have property1 that can have two text fields FillLevel1 and FillLevel2, I could receive messages on TCP which have both fill levels specified in text as F1=100;F2=90 Later I could add another filed say FillLevel3 when I start receiving messages F1=xx;F2=xx;F3=xx. But this is a conscious decision on the part of system modeler. My question is what do you think is better to use for parsing and storing the message. ETL (using Pantaho, which is used in other system) where you store the raw message and use task executor to consume them one by one and store the transformed messages as per your rules. One could use Espr or Drools to do the same thing , storing rules and executing them with timer, but I am not sure how dynamic you could get with making rules (they have to be made by end user in a running system and preferably in most user friendly way, ie no scripts or code, only GUI) The end user should be capable of changing the parse rules. It is also possible that end user might want to change the archived data as well (for example in the above example if a new value of FillLevel is added, one would like to put a FillLevel=-99 in the previous values to make the data consistent). Please ask for explanations, I have the feeling that I need to revise this question a bit. Thanks

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• How to implement IEquatable<T> when mutable fields are part of the equality - Problem with GetHashCo

  - by Shimmy

  Hello! I am using Entity Framework in my application. I implemented with the partial class of an entity the IEquatable<T> interface: Partial Class Address : Implements IEquatable(Of Address) 'Other part generated Public Overloads Function Equals(ByVal other As Address) As Boolean _ Implements System.IEquatable(Of Address).Equals If ReferenceEquals(Me, other) Then Return True Return AddressId = other.AddressId End Function Public Overrides Function Equals(ByVal obj As Object) As Boolean If obj Is Nothing Then Return MyBase.Equals(obj) If TypeOf obj Is Address Then Return Equals(DirectCast(obj, Address)) Else Return False End Function Public Overrides Function GetHashCode() As Integer Return AddressId.GetHashCode End Function End Class Now in my code I use it this way: Sub Main() Using e As New CompleteKitchenEntities Dim job = e.Job.FirstOrDefault Dim address As New Address() job.Addresses.Add(address) Dim contains1 = job.Addresses.Contains(address) 'True e.SaveChanges() Dim contains2 = job.Addresses.Contains(address) 'False 'The problem is that I can't remove it: Dim removed = job.Addresses.Remoeve(address) 'False End Using End Sub Note (I checked in the debugger visualizer) that the EntityCollection class stores its entities in HashSet so it has to do with the GetHashCode function, I want it to depend on the ID so entities are compared by their IDs. The problem is that when I hit save, the ID changes from 0 to its db value. So the question is how can I have an equatable object, being properly hashed. Please help me find what's wrong in the GetHashCode function (by ID) and what can I change to make it work. Thanks a lot.

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