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  • Define tables from a part of my ER Diagram.

    - by M R Jafari
    I have a ER-Diagram (Show in http://www.4freeimagehost.com/show.php?i=f82997ca4d5d.png). In the diagram you see 2 entities and a 1:N relataion together. Project has 2 columns as ProjectID, ProjectName. Employee has 3 colums as EmployeeID, EmployeeName and ProjectID. A project has ONLY 1 project-manager and project-manager is a employee. What columns add them?

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  • Value object or not for 3d points ?

    - by Stefano Borini
    I need to develop a geometry library in python, describing points, lines and planes in 3d space, and various geometry operations. Related to my previous question. The main issue in the design is if these entities should have identity or not. I was wondering if there's a similar library out there (developed in another language) to take inspiration from, what is the chosen design, and in particular the reason for one choice vs. the other.

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  • Remove then Query fails in JPA/Hibernate (deleted entity passed to persist)

    - by Kevin
    I've got a problem with the removal of entities in my JPA application: basically, I do in this EJB Business method: load photo list ; for each photo { //UPDATE remove TagPhoto element from @OneToMany relation //DISPLAY create query involving TagPhoto ... } and this last query always throws an EntityNotFoundException (deleted entity passed to persist: [...TagPhoto#]) I think I understand the meaning of this exception, like a synchronization problem caused by my Remove, but how can I get rid of it?

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  • What transaction manager should I use for JBDC template When using JPA ?

    - by Sajid
    I am using standard JPA transaction manager for my JPA transactions. However, now I want to add some JDBC entities which will share the same 'datasource'. How can I make the JDBC operations transactional with spring transaction? Do I need to swith to JTA transaction managers? Is it possible to use both JPA & JDBC transactional service with same datasource? Even better, is it possible to mix these two transactions?

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  • How to use NSPredicate with Key-Paths (and ALL)?

    - by Konstantin
    Taking example from Apple docs using predicates with Key-Paths NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY employees.firstName like 'Matthew'"]; Now, assume the employees has a bool field "isGood". The question: how do I select just those entities, having ALL of employees isGood==TRUE? I tried but failed with following predicates: "!(ANY employees.isGood != TRUE)" "(ALL employees.isGood == TRUE)" // Would be perfect, but throws an exception..

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  • Would ViewModels fit in the Model View Presenter pattern?

    - by Jonn
    Having used ViewModels in MVC, I was wondering if applying the same to the MVP pattern is practical. I only have a few considerations, one being that MVP is already fairly hard to implement (with all the additional coding, not much on the seeming complexity) or that ViewModels already have a slightly similar way of modeling data or entities. Would adding another layer in the form of ViewModels be redundant or is it a logical abstraction that I, as one implementing the MVP pattern, should adhere to?

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  • Functional programming approach for Java's input/output streams

    - by Elazar Leibovich
    I'm using Java's DataInputStream with scala to parse some simple binary file (which is very bad exprerience due to the lack of unsigned types, even in scala, but that's a different story). However I find myself forced to use mutable data structure, since Java's streams are inherently state preserving entities. What's a good design to wrap Java's streams with nice functional data structure?

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  • Hibernate custom join clause on association

    - by myso
    I would like to associate 2 entities using hibernate annotations with a custom join clause. The clause is on the usual FK/PK equality, but also where the FK is null. In SQL this would be something like: join b on a.id = b.a_id or b.a_id is null From what I have read I should use the @WhereJoinTable annotation on the owner entity, but I'm puzzled about how I specify this condition...especially the first part of it - referring to the joining entity's id. Does anyone have an example?

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  • Saving order of a List in JPA

    - by Rosen Martev
    Hello, I have the following question about JPA: Can I save the order of the elements in a java.util.List? In my application the order in which I put elements in the Lists is important but after I get those collections from the database the order is not the same (as expected). Can you show me a way to deal with this problem? P.S. There is not a field in the entities that I put in the collections by which I can order them. Rosen

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  • ASP.NET Elements are null when assigning data source

    - by deccks
    For some reason, all of the objects in my ASP.NET markup are now null when I try to assign values to their properties in the code behind. My project was going fine and then now when I try to assign a data source to a GridView, I get a null reference error. I have no idea why it's doing this. I am not doing nothing special. I am just trying to assign a value to a property to an asp.net element in on the page. The intellisense knows that the element is there and I get no errors when I build the project. It's just when I am running the website I get the null reference. I have been trying to fix this issue for a couple weeks now. Please Help. Thanks. Here is the code: protected void Page_PreRender(object sender, EventArgs e) { LoadData(); } private void LoadData() { Entities context = new Entities(); var types = (from t in context.CustomerTypes select t).OrderBy(t => t.TypeName); gvCustomerTypes.DataSource = types; gvCustomerTypes.DataBind(); } and on in the markup the gridview looks like this: <asp:GridView ID="gvCustomerTypes" runat="server" ShowHeader="true" GridLines="Both" AutoGenerateColumns="false" AlternatingRowStyle-BackColor="AliceBlue" Width="100%"> <Columns> <asp:TemplateField HeaderText="Customer Type Name" HeaderStyle-HorizontalAlign="Left" ItemStyle-HorizontalAlign="Left"> <ItemTemplate> <asp:Label ID="lblType" runat="server" Text='<%# Eval("TypeName") %>' /> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Edit" HeaderStyle-HorizontalAlign="Center" ItemStyle-HorizontalAlign="Center"> <ItemTemplate> <asp:HyperLink ID="HyperLink1" NavigateUrl='<%#Eval("CustomerTypeID", "CreateEditCustomerType.aspx?ID={0}") %>' Text="Edit" runat="server" /> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Delete" HeaderStyle-HorizontalAlign="Center" ItemStyle-HorizontalAlign="Center"> <ItemTemplate> <asp:LinkButton ID="LinkButton1" CommandName='<%#Eval("CustomerTypeID") %>' OnClientClick="javascript:return confirm('Are you sure you want to delete this Customer Type?');" OnCommand="DeleteCustomerType" Text="Delete" runat="server" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView>

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  • NHibernate requires events to be virtual?

    - by Jimit
    I'm attempting to map an entity hierarchy using NHibernate almost all of which have events. When attempting to build a session factory however, I get error messages similar to the following: Core.Domain.Entities.Delivery: method remove_Scheduled should be virtual Delivery is an entity in my domain model with an event called Scheduled. Since events cannot be declared virtual I'm at a loss as to how to proceed here. Why would NHibernate need events to be virtual?

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  • How do I use Entity Framework in a CLR stored procedure?

    - by Ivan
    I am looking forward to move all the logic (which is implemented as manipulating Entity Framework 4 objects) to a server side. It looks going to be simple (thanks to the application structure) and beneficial (as all I have is one oldy laptop as a client and one tough server which runs SQL Server 2008, and building a separate service for the logic can just introduce more latency if compared to doing it inside the database). So how do I correctly use Entities Framework inside a CLR stored procedure and make it using a host-server-provided SqlContext?

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  • Escaping textarea content

    - by user198729
    <textarea><?php echo htmlspecialchars($content)?></textarea> Does content inside <textarea need to be converted into HTML entities? Is htmlspecialchars necessary here? I tried with and without it, and both work for the content I used.

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  • How to disable sql creation for JPA entity classes

    - by Samuel
    We have some JPA entity classes which are currently under development and wouldn't want them as part of the testing cycle. We tried commenting out the relevant entity classes in META-INF\persistence.xml but the hbm2ddl reverse engineering tool still seems to generate SQL for those entities. How do I tell my code to ignore these classes? Are there any annotations for these or should I have to comment out the @Entity annotation along with my changes in persistence.xml file.

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  • How to make a nested query with an Entity that doesn't really exist (many-to-many)

    - by Calou
    Hi everyone, I'm new with Doctrine2 so my question can be easy to answer (I hope so). First of all, here the SQL query that I'd want : SELECT * FROM Document WHERE id NOT IN (SELECT document_id FROM Documents_Folders) Pretty simple isn't it ? The porblem is that my table 'Documents_Folders' is not an entity. In fact, it was create because I have a many-to-many relation between my entities 'Document' and 'Folder'. I tried several queries, but none worked. Thanks.

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  • ASP.NET Dynamic Data field value disappears in the browser.

    - by ProfK
    I have an ASP.NET Dynamic Data web application, with an entity called ActivationResource. One of the properties of this is a CellPhone field. Now, whenever I open a List or Details view of one of these entities, the cell phone number displays for a moment then disappears. Anyone have any ideas as to the cause of this mysterious behavior?

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  • hibernate modeling relationships managed through an intermediate table

    - by shikarishambu
    I have a datamodel that has an intermediate table to manage relationships between entities. For example, tables Person and Organization are related through the Relationship table Party (table) - ID Person (table) - ID (references Party.ID) - name Organization (table) -ID (references Party.ID) -name Relationship (table) -ID (PK) -type (references relationshiptype lookup) -fromID (references Party.ID) -ToID (references Party.ID) -fromDate -ToDate Type+fromID+ToID+fromDate+ToDate is guaranteed to be unique. How do I manage this using hibernate? TIA

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  • Robust way to save/load objects with dependencies?

    - by mrteacup
    I'm writing an Android game in Java and I need a robust way to save and load application state quickly. The question seems to apply to most OO languages. To understand what I need to save: I'm using a Strategy pattern to control my game entities. The idea is I have a very general Entity class which e.g. stores the location of a bullet/player/enemy and I then attach a Behaviour class that tells the entity how to act: class Entiy { float x; float y; Behavior b; } abstract class Behavior { void update(Entity e); {} // Move about at a constant speed class MoveBehavior extends Behavior { float speed; void update ... } // Chase after another entity class ChaseBehavior extends Behavior { Entity target; void update ... } // Perform two behaviours in sequence class CombineBehavior extends Behavior { Behaviour a, b; void update ... } Essentially, Entity objects are easy to save but Behaviour objects can have a semi-complex graph of dependencies between other Entity objects and other Behaviour objects. I also have cases where a Behaviour object is shared between entities. I'm willing to change my design to make saving/loading state easier, but the above design works really well for structuring the game. Anyway, the options I've considered are: Use Java serialization. This is meant to be really slow in Android (I'll profile it sometime). I'm worried about robustness when changes are made between versions however. Use something like JSON or XML. I'm not sure how I would cope with storing the dependencies between objects however. Would I have to give each object a unique ID and then use these IDs on loading to link the right objects together? I thought I could e.g. change the ChaseBehaviour to store a ID to an entity, instead of a reference, that would be used to look up the Entity before performing the behaviour. I'd rather avoid having to write lots of loading/saving code myself as I find it really easy to make mistakes (e.g. forgetting to save something, reading things out in the wrong order). Can anyone give me any tips on good formats to save to or class designs that make saving state easier?

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  • How to map a Entity Data Model conceptual model property to a storage model column using the "Serial

    - by codekaizen
    I have a conceptual model in EDM where one of the entities has a property which is essentially a big value object whose properties aren't really useful as columns in the datamodel. I'd like to apply the Serialized LOB pattern to it so that I can fit it into a 192 byte binary column. How do I map this in the EDM v4? Is it even possible at this time? Actually, is it possible in any ORM?

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  • Which is the "best" data access framework/approach for C# and .NET?

    - by Frans
    (EDIT: I made it a community wiki as it is more suited to a collaborative format.) There are a plethora of ways to access SQL Server and other databases from .NET. All have their pros and cons and it will never be a simple question of which is "best" - the answer will always be "it depends". However, I am looking for a comparison at a high level of the different approaches and frameworks in the context of different levels of systems. For example, I would imagine that for a quick-and-dirty Web 2.0 application the answer would be very different from an in-house Enterprise-level CRUD application. I am aware that there are numerous questions on Stack Overflow dealing with subsets of this question, but I think it would be useful to try to build a summary comparison. I will endeavour to update the question with corrections and clarifications as we go. So far, this is my understanding at a high level - but I am sure it is wrong... I am primarily focusing on the Microsoft approaches to keep this focused. ADO.NET Entity Framework Database agnostic Good because it allows swapping backends in and out Bad because it can hit performance and database vendors are not too happy about it Seems to be MS's preferred route for the future Complicated to learn (though, see 267357) It is accessed through LINQ to Entities so provides ORM, thus allowing abstraction in your code LINQ to SQL Uncertain future (see Is LINQ to SQL truly dead?) Easy to learn (?) Only works with MS SQL Server See also Pros and cons of LINQ "Standard" ADO.NET No ORM No abstraction so you are back to "roll your own" and play with dynamically generated SQL Direct access, allows potentially better performance This ties in to the age-old debate of whether to focus on objects or relational data, to which the answer of course is "it depends on where the bulk of the work is" and since that is an unanswerable question hopefully we don't have to go in to that too much. IMHO, if your application is primarily manipulating large amounts of data, it does not make sense to abstract it too much into objects in the front-end code, you are better off using stored procedures and dynamic SQL to do as much of the work as possible on the back-end. Whereas, if you primarily have user interaction which causes database interaction at the level of tens or hundreds of rows then ORM makes complete sense. So, I guess my argument for good old-fashioned ADO.NET would be in the case where you manipulate and modify large datasets, in which case you will benefit from the direct access to the backend. Another case, of course, is where you have to access a legacy database that is already guarded by stored procedures. ASP.NET Data Source Controls Are these something altogether different or just a layer over standard ADO.NET? - Would you really use these if you had a DAL or if you implemented LINQ or Entities? NHibernate Seems to be a very powerful and powerful ORM? Open source Some other relevant links; NHibernate or LINQ to SQL Entity Framework vs LINQ to SQL

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