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  • Entity Framework 4 - Delay Loading Expensive Fields

    - by JohnnyO
    I know this same question was asked for Entity Framework 1, but now that Entity Framework 4 has come out, and Microsoft claims that it provides all of the features of Linq to Sql + more, does Entity Framework now support lazy loading expensive properties? In Linq to Sql, this is extremely easy. There's a Delay Loaded option on any property (accessible through the Designer) that can simply be toggled on or off. Is there something similar in Entity Framework? Thanks

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  • How to model my database when using entity framework 4?

    - by Junior Ewing
    Trying to wrap my head around the best approach in modelling a database when we are using Entity Framework 4 as the ORM layer. We are going to use asp.net mvc 2 for the application. Is it worth trying to model using the class diagram modeller that comes with Visual Studio 2010 where you graphically configure your models into the EDMX file and then generate out the database structure? I have run into a bunch of non trivial issues and for complex many to many mappings or multi primary key entities the answer is not that obvious even after poking around a while with the tools. I figure its easy at this point to give up and start modelling the DB using real, working DB modelling tools and then try to generate out the EDMX from the database, rather than trying to do the model first approach.

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  • Entity Framework 4 - Handling very large (1000+ tables) data models?

    - by David Kreps
    We've got a database with over 1000+ tables and would like to consider using EF4 for our data access layer, but I'm concerned about the practical realities of using it for such a large data model. I've seen this question and read about the suggested solutions here and here. These may work, but appear to refer to the first version of the Entity Framework (and are more complex than I'd like). Does anyone know if these solutions have been improved upon in EF4? Or have other suggestions all together? Thanks.

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  • SQL Server Management Studio Reports: Why no open transactions?

    - by Sleepless
    On a server with several hundred user connections, when I open the SQL Server 2008 SP1 Management Studio report "Database - User Statistics", the result page shows the following results: Login Name: appUser Active Sessions: 243 Active Connections: 243 Open Transactions: 374 Still, when I open the report "Database - All Transactions" on the same DB, it doesn't show any connections ("Currently, there are no transactions running for [Database Name] Database"). What gives? Is this a bug in Management Studio? This is not the only report where this kind of behavious happens... Thanks all!

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  • Obstacle Avoidance steering behavior: how can an entity avoid an obstacle while other forces are acting on the entity?

    - by Prog
    I'm trying to implement the Obstacle Avoidance steering behavior in my 2D game. Currently my approach is to apply a force on the entity, in the direction of the normal of the heading, scaled by a number that gets bigger the closer we are to the obstacle. This is supposed to push the entity to the side and avoid the obstacle that blocks it's way. However, in the same time that my entity tries to avoid an obstacle, it Seeks to a point more or less behind the obstacle (which is the reason it needs to avoid the obstacle in the first place). The Seek algorithm constantly applies a force on the entity that pushes it (more or less) in the direction of the obstacle, while the Obstacle Avoidance algorithm constantly applies a force that pushes the entity away (more accurately, to the side) of the obstacle. The result is that sometimes the entity succesfully avoids the obstacle, and sometimes it collides with it, depending on the strength of the avoidance force I'm applying. How can I make sure that a force will succeed in steering the entity in some direction, while other forces are currently acting on the entity? (And while still looking natural). I can't allow entities to collide with obstacles when realistically they should be able to easily avoid them, doesn't matter what they're currently doing. Also, the Obstacle Avoidance algorithm is made exactly for the case where another force is acting on the entity. Otherwise it wouldn't be moving and there would be no need to avoid anything. So maybe I'm missing something. Thanks

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  • NServiceBus and NHibernate - Message Handler and Transactions

    - by mattcodes
    From my understanding NServiceBus executes the Handle method of an IMessageHandler within a transaction, if an exception propagates out of this method, then NServiceBus will ensure the message is put back on the message queue (up X amount of times before error queue) etc.. so we have an atomic operation so to speak. Now when if I inside my NServiceBus Message Handle method I do something like this using(var trans = session.BeginTransaction()) { person.Age = 10; session.Update<Person>(person); trans.Commit() } using(var trans2 = session.BeginTransaction()) { person.Age = 20; session.Update<Person>(person); // throw new ApplicationException("Oh no"); trans2.Commit() } What is the effect of this on the transaction scope? Is trans1 now counted as a nested transaction in terms of its relationship with the Nservicebus transaction even though we have done nothing to marry them up? (if not how would one link onto the transaction of NServiceBus? Looking at the second block (trans2), if I uncomment the throw statement, will the NServiceBus transaction then rollback trans1 as well? In basic scenarios, say I dump the above into a console app, then trans1 is independent, commit, flushed and won't rollback. I'm trying to clarify what happens now we sit in someone else's transaction like NServiceBus? The above is just example code, im wouldnt be working directly with session, more like through a uow pattern.

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  • Hibernate session problem for transactions.

    - by Jani
    Hi all, I am new to hibernate and trying integrate hibernate with an existing spring based application. I configured session factory and transaction manager, transaction proxy template. I am also using Quartz scheduler in this application. When I run the application, I am getting the following exception. ERROR au.com.michaelpage.ctsgui.utils.OrganisationMergeProfileThread - Error while updating opportunity: Could not open Hibernate Session for transaction; nested exception is java.lang.IllegalStateException: Already value [org.springframework.jdbc.datasource.ConnectionHolder@9f6885] for key [weblogic.jdbc.common.internal.RmiDataSource@32b034] bound to thread [DefaultQuartzScheduler_Worker-0] My hibernate session configuration: <bean id="sessionFactoryAU" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="dataSource"> <ref bean="profileAU" /> </property> <property name="mappingResources"> <list> <value> /au/com/michaelpage/ctsgui/hibernate/dao/mappings/Opportunity.hbm.xml </value> <value> /au/com/michaelpage/ctsgui/hibernate/dao/mappings/Position.hbm.xml </value> <value> /au/com/michaelpage/ctsgui/hibernate/dao/mappings/EventRole.hbm.xml </value> </list> </property> <property name="hibernateProperties"> <props> <!-- Database Settings --> <prop key="hibernate.dialect"> org.hibernate.dialect.SybaseDialect </prop> <prop key="hibernate.query.factory_class"> org.hibernate.hql.ast.ASTQueryTranslatorFactory </prop> <!-- Cache settings --> <prop key="hibernate.cache.provider_class"> org.hibernate.cache.EhCacheProvider </prop> </props> </property> </bean> <!-- Transaction manager for a Hibernate SessionFactory --> <bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory"> <ref bean="sessionFactoryAU" /> </property> </bean> <!-- Transaction template for Managers --> <bean id="txProxyTemplateHibernateProfileAU" abstract="true" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean"> <property name="transactionManager"> <ref bean="txManager" /> </property> <property name="transactionAttributes"> <props> <prop key="create*">PROPAGATION_REQUIRED</prop> <prop key="save*">PROPAGATION_REQUIRED</prop> <prop key="update*">PROPAGATION_REQUIRED</prop> <prop key="delete*">PROPAGATION_REQUIRED</prop> <prop key="remove*">PROPAGATION_REQUIRED</prop> <prop key="get*">PROPAGATION_SUPPORTS</prop> </props> </property> </bean> <bean id="organisationMergeProfileMgrAU" parent="txProxyTemplateHibernateProfileAU"> <property name="target"> <bean class="au.com.michaelpage.ctsgui.mgr.profile.OrganisationMergeProfileMgrImpl"> <property name="commonProfileDao"> <ref bean="commonProfileDaoAU" /> </property> <property name="organisationMergeProfileDao"> <ref bean="organisationMergeDaoAU" /> </property> <property name="hibernateOrganisationDAO"> <ref bean="hibernateOrganisationDAOAU" /> </property> <property name="hibernateOpportunityDAO"> <ref bean="hibernateOpportunityDAOAU" /> </property> <property name="hibernatePositionDAO"> <ref bean="hibernatePositionDAOAU" /> </property> <property name="hibernateEventRoleDAO"> <ref bean="hibernateEventRoleDAOAU" /> </property> </bean> </property> </bean> My Quartz scheduler configuration: <bean id="organisationMergeJobDetail" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean"> <property name="targetObject" ref="organisationMergeJob" /> <property name="targetMethod" value="execute" /> <property name="concurrent" value="false" /> </bean> <bean id="organisationMergeProfileRegularCheckerTrigger" class="org.springframework.scheduling.quartz.SimpleTriggerBean"> <property name="jobDetail" ref="organisationMergeJobDetail" /> <property name="repeatInterval"> <util:constant static-field="au.com.michaelpage.ctsgui.common.Constants.CHECK_FREQUENCY" /> </property> </bean> Here is the bean definition for 'organisationMergeJob' <bean id="organisationMergeJob" class="au.com.michaelpage.ctsgui.utils.OrganisationMergeProfileThread"> <property name="organisationMergeMgr" ref="organisationMergeMgr"/> </bean> <bean id="organisationMergeMgr" class="au.com.michaelpage.ctsgui.mgr.OrganisationMergeMgrImpl"> <property name="organisationMergeDao" ref="organisationMergeDao"/> </bean> Any help to solve this? Thank you in advance. Hi skaffman, Here is the stack trace of the error: Could not open Hibernate Session for transaction; nested exception is java.lang.IllegalStateException: Already value [org.springframework.jdbc.datasource.ConnectionHolder@5f2fb8] for key [weblogic.jdbc.common.internal.RmiDataSource@326b7b] bound to thread [DefaultQuartzScheduler_Worker-3] Caused by: java.lang.IllegalStateException: Already value [org.springframework.jdbc.datasource.ConnectionHolder@5f2fb8] for key [weblogic.jdbc.common.internal.RmiDataSource@326b7b] bound to thread [DefaultQuartzScheduler_Worker-3] at org.springframework.transaction.support.TransactionSynchronizationManager.bindResource(TransactionSynchronizationManager.java:163) at org.springframework.orm.hibernate3.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:526) at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:350) at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:262) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:101) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204) at $Proxy73.updateEventRole(Unknown Source) 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:597) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204) at $Proxy73.updateEventRole(Unknown Source) at au.com.michaelpage.ctsgui.utils.OrganisationMergeProfileThread.execute(OrganisationMergeProfileThread.java:100) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.util.MethodInvoker.invoke(MethodInvoker.java:283) at org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean$MethodInvokingJob.executeInternal(MethodInvokingJobDetailFactoryBean.java:272) at org.springframework.scheduling.quartz.QuartzJobBean.execute(QuartzJobBean.java:86) at org.quartz.core.JobRunShell.run(JobRunShell.java:203) at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:520) Thank you. Here is the bean definition for 'organisationMergeMgr' <bean id="organisationMergeMgr" class="au.com.michaelpage.ctsgui.mgr.OrganisationMergeMgrImpl"> <property name="organisationMergeDao" ref="organisationMergeDao"/> </bean>

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  • Using separate model methods to manage transactions

    - by DCrystal
    If i’ve got 2(or more) model methods which do (for example, in billing system) enrolling/withdrawing, and one controller’s method that calls 2(or more) of these model methods. Is it a good way(maybe, any suggestions how to do it better) to write/use 2model methods like these: public function start_transaction(){ $this->db->trans_start(); } public function end_transaction(){ $this->db->trans_complete(); } And call in controller’s method: public function smth(){ //something $this->model->start_transaction(); $this->model->enroll(); //something else $this->model->withdraw(); $this->model->end_transaction(); } Will transaction be reversed, if model's withdraw() method fails? Thanks.

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  • MySQL: Transactions across multiple threads

    - by Zombies
    Preliminary: I have an application which maintains a thread pool of about 100 threads. Each thread can last about 1-30 seconds before a new task replaces it. When a thread end, that thread almost always will result in inserting 1-3 records into a table, this table is used by all of the threads. Right now, no transactional support exists, but I am trying to add that now. So... Goal I want to implement a transaction for this. The rules for whether or not this transaction commits or rollback reside in the main thread. Basically there is a simple function that will return a boolean. Can I implement a transaction across multiple connections? If not, can multiple threads share the same connection? (Note: there are a LOT of inserts going on here, and that is a requirement).

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  • .NET Data Providers - How do I determine what they can do?

    - by rbellamy
    I have code which could be executed using a Provider that doesn't support transactions, or doesn't support nested transactions. How would I programmatically determine such support? E.g. The code below throws a System.InvalidOperationException on the final commit when using the MySQL .NET Connector, but works fine for MSSQL. I'd like to be able to alter the code to accommodate various providers, without having to hardcode tests based on the type of provider (E.g. I don't want to have to do if(typeof(connection) == "some provider name")) using (IDbConnection connection = Use.Connection(ConnectionStringName)) using (IDbTransaction transaction = connection.BeginTransaction()) { using (currentCommand = connection.CreateCommand()) { using (IDbCommand cmd = connection.CreateCommand()) { currentCommand = cmd; currentCommand.Transaction = transaction; currentCommand.ExecuteNonQuery(); } if (PipelineExecuter.HasErrors) { transaction.Rollback(); } else { transaction.Commit(); } } transaction.Commit(); }

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  • Group Policy for DNS Server Addresses

    - by John
    This question deals strictly with the methodology of using Active Directory to publish DNS settings and controlling the DNS server address order to domain attached clients. This is not asking about if this is the right function, role, or best use of group policy; but rather, how to make it work. I would like to be able to publish in group policy DNS addresses and possibly control the order in which the client consumes the addresses. I have tried following the information from this site without success. I set the following setting within group policy, but the client never shows the settings within the TCP/IP properties. Computer Configuration/Administrative Templates/Network/DNS Client/DNS Servers I did list them as a single space separated list. For example, the following: 192.168.0.1 192.168.10.3 192.168.34.2 192.168.2.67 192.168.56.99 192.168.99.23 This would be for Windows 7, Windows Server 2003, and Windows Server 2008 clients. I am not sure what I am doing wrong or how to get this to work. Am I missing a setting? Do I need to set something differently?

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  • Problems installing Windows service via Group Policy in a domain

    - by CraneStyle
    I'm reasonably new to Group Policy administration and I'm trying to deploy an MSI installer via Active Directory to install a service. In reality, I'm a software developer trying to test how my service will be installed in a domain environment. My test environment: Server 2003 Domain Controller About 10 machines (between XP SP3, and server 2008) all joined to my domain. No real other setup, or active directory configuration has been done apart from things like getting DNS right. I suspect that I may be missing a step in Group Policy that says I need to grant an explicit permission somewhere, but I have no idea where that might be or what it will say. What I've done: I followed the documentation from Microsoft in How to Deploy Software via Group Policy, so I believe all those steps are correct (I used the UNC path, verified NTFS permissions, I have verified the computers and users are members of groups that are assigned to receive the policy etc). If I deploy the software via the Computer Configuration, when I reboot the target machine I get the following: When the computer starts up it logs Event ID 108, and says "Failed to apply changes to software installation settings. Software changes could not be applied. A previous log entry with details should exist. The error was: An operations error occurred." There are no previous log entries to check, which is weird because if it ever actually tried to invoke the windows installer it should log any sort of failure of my application's installer. If I open a command prompt and manually run: msiexec /qb /i \\[host]\[share]\installer.msi It installs the service just fine. If I deploy the software via the User Configuration, when I log that user in the Event Log says that software changes were applied successfully, but my service isn't installed. However, when deployed via the User configuration even though it's not installed when I go to Control Panel - Add/Remove Programs and click on Add New Programs my service installer is being advertised and I can install/remove it from there. (this does not happen when it's assigned to computers) Hopefully that wall of text was enough information to get me going, thanks all for the help.

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  • Grails Services / Transactions / RuntimeException / Testing

    - by Rob
    I'm testing come code in a service with transactional set to true , which talks to a customer supplied web service the main part of which looks like class BarcodeService { .. /// some stuff ... try{ cancelBarCodeResponse = cancelBarCode(cancelBarcodeRequest) } catch(myCommsException e) { throw new RuntimeException(e) } ... where myCommsException extends Exception .. I have a test which looks like // As no connection from my machine, it should fail .. shouldFailWithCause(RuntimeException){ barcodeServices.cancelBarcodeDetails() } The test fails cause it's catching a myCommsException rather than the RuntimeException i thought i'd converted it to .. Anyone care to point out what i'm doing wrong ? Also will the fact that it's not a RuntimeException mean any transaction related info done before my try/catch actually be written out rather than thrown away ?? Thanks

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  • User Group Policy in Server 2008 to set Default Profile settings

    - by Chris
    I have computers to deploy and want to apply changes to the default user policy on these PCs automatically. What's the best way to do this? Our current procedure is: Create the computer account in an OU called "Deployment" on our server Unbox the PC Login as the user who will be receiving the PC Change settings (pre-configure outlook, authorize Office, etc.) move computer account to correct OU Place the PC on the users desk. I would like to make as many of the changes in step #4 with Group Policies applied to the Deployment OU if possible since they're largely repeated for every computer. There are a dozen policies created and the computer ones apply correctly but the user policies do not. I understand this is because the end user is not in our "Deployment" OU. I don't want to apply these settings to the user at their current station just the new PC I'm working on. I believe I have the desired effect with Group Policy Loopback Replace enabled on policies that need user policies changed but this just feels wrong/inefficient/complicated to maintain. Am I doing this correctly? Is Group Policy Loopback the only way to change user accounts on one computer? What do you do to setup a user on a new PC?

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  • SQL Server 2005 Transactions

    - by mcallec
    I have a long running stored proc (approx 30 mins) which is currently running within a transaction (isolation level snapshot). I've set the transaction to snapshot to avoid locking records preventing other processes from accessing the data. What I'm trying to do is write to and read from a status table, but although we're in a transaction I'd like to write to and read from the status table as if I'm not in a transaction. I need this so that other processes can read any updates to this table by my stored proc, and this stored proc can also read any inserts made by other processes. I realise that having my entire stored proc running within a transaction isn't recommended, but this has been done for other reasons and we need to stick with that approach. So my question is within a transaction, is it possible to execute a query or call a stored proc which effectively isn't enlisted in the transaction?

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  • 2-Way databinding with Entity Framework and WPF DataGrid , is Possible ?

    - by Panindra
    i am working on POS application using SQL CE , WPF , Entity framework 3.5sp2 and iam trying to use data grid as my Order Entry Control for User to enter Products Order . Iam plannning to bind this to enitiy frmae work model , abd looking for 2 way updating ? private void button1_Click(object sender, RoutedEventArgs e) { using (MasterEntities nwEntities = new MasterEntities()) { var users = from d in nwEntities.Companies select new { d.CompanyId, d.CompanyName, d.Place }; listBox1.DataContext = users; dataGrid1.DataContext = users; // foreach (String c in customers) // { // MessageBox.Show(c.ToString()); // } } } When try to double clikc on the datagrid it through s a error with Caption " Invalid Operation Execption was unhandled " and Message " A TwoWay or OneWayToSource binding cannot work on the read-only property 'CompanyId' of type '<f__AnonymousType0`3[System.Int32,System.String,System.String]'. whats wrong here and my xaml coding goes like this <Grid> <ListBox Name="listBox1" ItemsSource="{Binding}" /> <Button Content="Show " Name="button1" Click="button1_Click" /> <DataGrid AutoGenerateColumns="False" Name="dataGrid1" ItemsSource="{Binding}" > <DataGrid.Columns> <DataGridTextColumn Header=" ID" Binding="{Binding CompanyId}"/> <DataGridTextColumn Header="Company Name" Binding="{Binding CompanyName}"/> <DataGridTextColumn Header="Place" Binding="{Binding Place}" /> </DataGrid.Columns> </DataGrid> </Grid> EDITED : i made the changes shown by @vorrtex, But, then i added another button to save the chages and in button click event i added follwing code , butit showing Updating error private void button2_Click(object sender, RoutedEventArgs e) { nwEntities.SaveChanges(); }

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  • A question about entities, roles and interfaces in Entity Framework 4.

    - by mvole
    Hi, I am an experienced .NET developer but new to EF - so please bear with me. I will use an example of a college application to illustrate my problem. I have these user roles: Lecturer, Student, Administrator. In my code I envisage working with these entities as distinct classes so e.g. a Lecturer teaches a collection of Students. And work with 'is Student' 'TypeOf' etc. Each of these entities share lots of common properties/methods e.g. they can all log onto the system and do stuff related to their role. In EF designer I can create a base entity Person (or User...) and have Lecturer, Student and Administrator all inherit from that. The difficulty I have is that a Lecturer can be an Administrator - and in fact on occasion a Student can be a Lecturer. If I were to add other entities such as Employee and Warden then this gets even more of an issue. I could presumably work with Interfaces so a person could implement ILecturer and IStudent, however I do not see how this fits within EF. I would like to work within the EF designer if possible and I'm working model-first (coding in C#). So any help and advice/samples would be very welcome and much appreciated. Thanks

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  • Entity Framework LINQ Query using Custom C# Class Method - Once yes, once no - because executing on the client or in SQL?

    - by BrooklynDev
    I have two Entity Framework 4 Linq queries I wrote that make use of a custom class method, one works and one does not: The custom method is: public static DateTime GetLastReadToDate(string fbaUsername, Discussion discussion) { return (discussion.DiscussionUserReads.Where(dur => dur.User.aspnet_User.UserName == fbaUsername).FirstOrDefault() ?? new DiscussionUserRead { ReadToDate = DateTime.Now.AddYears(-99) }).ReadToDate; } The linq query that works calls a from after a from, the equivalent of SelectMany(): from g in oc.Users.Where(u => u.aspnet_User.UserName == fbaUsername).First().Groups from d in g.Discussions select new { UnReadPostCount = d.Posts.Where(p => p.CreatedDate > DiscussionRepository.GetLastReadToDate(fbaUsername, p.Discussion)).Count() }; The query that does not work is more like a regular select: from d in oc.Discussions where d.Group.Name == "Student" select new { UnReadPostCount = d.Posts.Where(p => p.CreatedDate > DiscussionRepository.GetLastReadToDate(fbaUsername, p.Discussion)).Count(), }; The error I get is: LINQ to Entities does not recognize the method 'System.DateTime GetLastReadToDate(System.String, Discussion)' method, and this method cannot be translated into a store expression. My question is, why am I able to use my custom GetLastReadToDate() method in the first query and not the second? I suppose this has something to do with what gets executed on the db server and what gets executed on the client? These queries seem to use the GetLastReadToDate() method so similarly though, I'm wondering why would work for the first and not the second, and most importantly if there's a way to factor common query syntax like what's in the GetLastReadToDate() method into a separate location to be reused in several different places LINQ queries. Please note all these queries are sharing the same object context.

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  • Entity Relationship Diagram - Relationship Strength?

    - by 01010011
    Hi, I am trying to figure out under what circumstances I should use weak (non-identifying) relationships (where the primary key of the related entity does not contain a primary key component of the parent entity), verses when I should use strong (identifying) relationships (primary key of the related entity contains a primary key component of the parent entity). For example, when designing an Entity Relationship Diagram , if I have two entities, (e.g. book and purchaser), how do I know when to choose the solid Crows Foot or the dashed Crows Foot to connect the two entities? Any assistance will be appreciated. Thanks in advance.

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  • Entity Framework mant to many insert

    - by Jacob
    I've been playing around with Entity Framework v2 and added some code to insert new entity with many to many relationship , lets say this entity is called meeting. I add hours to meeting : meeting.Hours.Add(hour); and I get different errors on different occasions On Update : Cannot insert the value NULL into column 'Meetings_Id', table 'Plan.dbo.MeetingHour'; column does not allow nulls. INSERT fails. The statement has been terminated. On Inset : An item with the same key has already been added. But the tricky party is that if I add this manually trough SQL Server Management Studio , I can update the entity with the same value , clearing it first (meeting.Hour.Clear()) Can't see what could be the problem , maybe entity model isn't mapped correctly ?

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  • flex/actionscript client entity state refresh on JPA update using Pimento EntityManager

    - by Chris
    My Flex application uses a client-side pimento EntityManager which fetches quite a few objects and associations. It does this by forcing eager fetching of particular association ends in the form of fetch plans. I would like to update the client whenever a change has been made to an entity existing in the EntityManager's cache. Is it possible to update the state of the changed entity ONLY, including updating which entities are associated, without resetting the state of these associated entities? I have setup an EntityListener with a JPA post-update method that notifies clients when a persisted entity has been updated. I want this to trigger a refresh for the modified client-side entity, but calling EntityManager.refresh(entity) resets all lazy associations to proxies. Initializing these proxies resets the associated entities, even if they were loaded previously. I'm looking for an efficient way to keep the client's state in synch with the server's state, at least with respect to the entities that have already been retrieved by the initial load.

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