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  • Inheritance Mapping Strategies with Entity Framework Code First CTP5 Part 1: Table per Hierarchy (TPH)

    - by mortezam
    A simple strategy for mapping classes to database tables might be “one table for every entity persistent class.” This approach sounds simple enough and, indeed, works well until we encounter inheritance. Inheritance is such a visible structural mismatch between the object-oriented and relational worlds because object-oriented systems model both “is a” and “has a” relationships. SQL-based models provide only "has a" relationships between entities; SQL database management systems don’t support type inheritance—and even when it’s available, it’s usually proprietary or incomplete. There are three different approaches to representing an inheritance hierarchy: Table per Hierarchy (TPH): Enable polymorphism by denormalizing the SQL schema, and utilize a type discriminator column that holds type information. Table per Type (TPT): Represent "is a" (inheritance) relationships as "has a" (foreign key) relationships. Table per Concrete class (TPC): Discard polymorphism and inheritance relationships completely from the SQL schema.I will explain each of these strategies in a series of posts and this one is dedicated to TPH. In this series we'll deeply dig into each of these strategies and will learn about "why" to choose them as well as "how" to implement them. Hopefully it will give you a better idea about which strategy to choose in a particular scenario. Inheritance Mapping with Entity Framework Code FirstAll of the inheritance mapping strategies that we discuss in this series will be implemented by EF Code First CTP5. The CTP5 build of the new EF Code First library has been released by ADO.NET team earlier this month. EF Code-First enables a pretty powerful code-centric development workflow for working with data. I’m a big fan of the EF Code First approach, and I’m pretty excited about a lot of productivity and power that it brings. When it comes to inheritance mapping, not only Code First fully supports all the strategies but also gives you ultimate flexibility to work with domain models that involves inheritance. The fluent API for inheritance mapping in CTP5 has been improved a lot and now it's more intuitive and concise in compare to CTP4. A Note For Those Who Follow Other Entity Framework ApproachesIf you are following EF's "Database First" or "Model First" approaches, I still recommend to read this series since although the implementation is Code First specific but the explanations around each of the strategies is perfectly applied to all approaches be it Code First or others. A Note For Those Who are New to Entity Framework and Code-FirstIf you choose to learn EF you've chosen well. If you choose to learn EF with Code First you've done even better. To get started, you can find a great walkthrough by Scott Guthrie here and another one by ADO.NET team here. In this post, I assume you already setup your machine to do Code First development and also that you are familiar with Code First fundamentals and basic concepts. You might also want to check out my other posts on EF Code First like Complex Types and Shared Primary Key Associations. A Top Down Development ScenarioThese posts take a top-down approach; it assumes that you’re starting with a domain model and trying to derive a new SQL schema. Therefore, we start with an existing domain model, implement it in C# and then let Code First create the database schema for us. However, the mapping strategies described are just as relevant if you’re working bottom up, starting with existing database tables. I’ll show some tricks along the way that help you dealing with nonperfect table layouts. Let’s start with the mapping of entity inheritance. -- The Domain ModelIn our domain model, we have a BillingDetail base class which is abstract (note the italic font on the UML class diagram below). We do allow various billing types and represent them as subclasses of BillingDetail class. As for now, we support CreditCard and BankAccount: Implement the Object Model with Code First As always, we start with the POCO classes. Note that in our DbContext, I only define one DbSet for the base class which is BillingDetail. Code First will find the other classes in the hierarchy based on Reachability Convention. public abstract class BillingDetail  {     public int BillingDetailId { get; set; }     public string Owner { get; set; }             public string Number { get; set; } } public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } } public class CreditCard : BillingDetail {     public int CardType { get; set; }                     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } } public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; } } This object model is all that is needed to enable inheritance with Code First. If you put this in your application you would be able to immediately start working with the database and do CRUD operations. Before going into details about how EF Code First maps this object model to the database, we need to learn about one of the core concepts of inheritance mapping: polymorphic and non-polymorphic queries. Polymorphic Queries LINQ to Entities and EntitySQL, as object-oriented query languages, both support polymorphic queries—that is, queries for instances of a class and all instances of its subclasses, respectively. For example, consider the following query: IQueryable<BillingDetail> linqQuery = from b in context.BillingDetails select b; List<BillingDetail> billingDetails = linqQuery.ToList(); Or the same query in EntitySQL: string eSqlQuery = @"SELECT VAlUE b FROM BillingDetails AS b"; ObjectQuery<BillingDetail> objectQuery = ((IObjectContextAdapter)context).ObjectContext                                                                          .CreateQuery<BillingDetail>(eSqlQuery); List<BillingDetail> billingDetails = objectQuery.ToList(); linqQuery and eSqlQuery are both polymorphic and return a list of objects of the type BillingDetail, which is an abstract class but the actual concrete objects in the list are of the subtypes of BillingDetail: CreditCard and BankAccount. Non-polymorphic QueriesAll LINQ to Entities and EntitySQL queries are polymorphic which return not only instances of the specific entity class to which it refers, but all subclasses of that class as well. On the other hand, Non-polymorphic queries are queries whose polymorphism is restricted and only returns instances of a particular subclass. In LINQ to Entities, this can be specified by using OfType<T>() Method. For example, the following query returns only instances of BankAccount: IQueryable<BankAccount> query = from b in context.BillingDetails.OfType<BankAccount>() select b; EntitySQL has OFTYPE operator that does the same thing: string eSqlQuery = @"SELECT VAlUE b FROM OFTYPE(BillingDetails, Model.BankAccount) AS b"; In fact, the above query with OFTYPE operator is a short form of the following query expression that uses TREAT and IS OF operators: string eSqlQuery = @"SELECT VAlUE TREAT(b as Model.BankAccount)                       FROM BillingDetails AS b                       WHERE b IS OF(Model.BankAccount)"; (Note that in the above query, Model.BankAccount is the fully qualified name for BankAccount class. You need to change "Model" with your own namespace name.) Table per Class Hierarchy (TPH)An entire class hierarchy can be mapped to a single table. This table includes columns for all properties of all classes in the hierarchy. The concrete subclass represented by a particular row is identified by the value of a type discriminator column. You don’t have to do anything special in Code First to enable TPH. It's the default inheritance mapping strategy: This mapping strategy is a winner in terms of both performance and simplicity. It’s the best-performing way to represent polymorphism—both polymorphic and nonpolymorphic queries perform well—and it’s even easy to implement by hand. Ad-hoc reporting is possible without complex joins or unions. Schema evolution is straightforward. Discriminator Column As you can see in the DB schema above, Code First has to add a special column to distinguish between persistent classes: the discriminator. This isn’t a property of the persistent class in our object model; it’s used internally by EF Code First. By default, the column name is "Discriminator", and its type is string. The values defaults to the persistent class names —in this case, “BankAccount” or “CreditCard”. EF Code First automatically sets and retrieves the discriminator values. TPH Requires Properties in SubClasses to be Nullable in the Database TPH has one major problem: Columns for properties declared by subclasses will be nullable in the database. For example, Code First created an (INT, NULL) column to map CardType property in CreditCard class. However, in a typical mapping scenario, Code First always creates an (INT, NOT NULL) column in the database for an int property in persistent class. But in this case, since BankAccount instance won’t have a CardType property, the CardType field must be NULL for that row so Code First creates an (INT, NULL) instead. If your subclasses each define several non-nullable properties, the loss of NOT NULL constraints may be a serious problem from the point of view of data integrity. TPH Violates the Third Normal FormAnother important issue is normalization. We’ve created functional dependencies between nonkey columns, violating the third normal form. Basically, the value of Discriminator column determines the corresponding values of the columns that belong to the subclasses (e.g. BankName) but Discriminator is not part of the primary key for the table. As always, denormalization for performance can be misleading, because it sacrifices long-term stability, maintainability, and the integrity of data for immediate gains that may be also achieved by proper optimization of the SQL execution plans (in other words, ask your DBA). Generated SQL QueryLet's take a look at the SQL statements that EF Code First sends to the database when we write queries in LINQ to Entities or EntitySQL. For example, the polymorphic query for BillingDetails that you saw, generates the following SQL statement: SELECT  [Extent1].[Discriminator] AS [Discriminator],  [Extent1].[BillingDetailId] AS [BillingDetailId],  [Extent1].[Owner] AS [Owner],  [Extent1].[Number] AS [Number],  [Extent1].[BankName] AS [BankName],  [Extent1].[Swift] AS [Swift],  [Extent1].[CardType] AS [CardType],  [Extent1].[ExpiryMonth] AS [ExpiryMonth],  [Extent1].[ExpiryYear] AS [ExpiryYear] FROM [dbo].[BillingDetails] AS [Extent1] WHERE [Extent1].[Discriminator] IN ('BankAccount','CreditCard') Or the non-polymorphic query for the BankAccount subclass generates this SQL statement: SELECT  [Extent1].[BillingDetailId] AS [BillingDetailId],  [Extent1].[Owner] AS [Owner],  [Extent1].[Number] AS [Number],  [Extent1].[BankName] AS [BankName],  [Extent1].[Swift] AS [Swift] FROM [dbo].[BillingDetails] AS [Extent1] WHERE [Extent1].[Discriminator] = 'BankAccount' Note how Code First adds a restriction on the discriminator column and also how it only selects those columns that belong to BankAccount entity. Change Discriminator Column Data Type and Values With Fluent API Sometimes, especially in legacy schemas, you need to override the conventions for the discriminator column so that Code First can work with the schema. The following fluent API code will change the discriminator column name to "BillingDetailType" and the values to "BA" and "CC" for BankAccount and CreditCard respectively: protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder) {     modelBuilder.Entity<BillingDetail>()                 .Map<BankAccount>(m => m.Requires("BillingDetailType").HasValue("BA"))                 .Map<CreditCard>(m => m.Requires("BillingDetailType").HasValue("CC")); } Also, changing the data type of discriminator column is interesting. In the above code, we passed strings to HasValue method but this method has been defined to accepts a type of object: public void HasValue(object value); Therefore, if for example we pass a value of type int to it then Code First not only use our desired values (i.e. 1 & 2) in the discriminator column but also changes the column type to be (INT, NOT NULL): modelBuilder.Entity<BillingDetail>()             .Map<BankAccount>(m => m.Requires("BillingDetailType").HasValue(1))             .Map<CreditCard>(m => m.Requires("BillingDetailType").HasValue(2)); SummaryIn this post we learned about Table per Hierarchy as the default mapping strategy in Code First. The disadvantages of the TPH strategy may be too serious for your design—after all, denormalized schemas can become a major burden in the long run. Your DBA may not like it at all. In the next post, we will learn about Table per Type (TPT) strategy that doesn’t expose you to this problem. References ADO.NET team blog Java Persistence with Hibernate book a { text-decoration: none; } a:visited { color: Blue; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } p.MsoNormal { margin-top: 0in; margin-right: 0in; margin-bottom: 10.0pt; margin-left: 0in; line-height: 115%; font-size: 11.0pt; font-family: "Calibri" , "sans-serif"; }

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  • PowerPivot and Parent/Child hierarchies

    - by AlbertoFerrari
    Does PowerPivot handle Parent/Child hierarchies? The common answer is “no”, since it does not handle them natively. During last PowerPivot course in London, I have been asked the same question once more and had an interesting discussion about this severe limitation of the PowerPivot data modeling and visualization capabilities. On my way back in Italy, I started thinking at a possible solution and, after some work, I managed to make PowerPivot handle Parent/Child hierarchies in a very nice way, which...(read more)

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  • PowerPivot, Parent/Child and Unary Operators

    - by AlbertoFerrari
    Following my last post about parent/child hierarchies in PowerPivot, I worked a bit more to implement a very useful feature of Parent/Child hierarchies in SSAS which is obviously missing in PowerPivot, i.e. unary operators. A unary operator is simply the aggregation function that needs to be used to aggregate values of children over their parent. Unary operators are very useful in accountings where you might have incomes and expenses in the same hierarchy and, at the total level, you want to subtract...(read more)

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  • C# - Close a child form from parent

    - by Nate Shoffner
    I have a parent form and a child form. I need to open the child form at the beginning of a method, do some pretty intensive tasks and then close the child form upon completion. Here is basically what I've tried so far (with no luck): Parent Form: Child child = new Child(); Method() { child.ShowDialog(); //Method code here child.CloseScan(); } Child Form: public void CloseScan() { this.Close(); }

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  • Code First / Database First / Model First : are they just personnal preferences?

    - by Antoine M
    Merely knowing the internal functionality of each approaches, and after reading a lot of posts, I still can't figure out if each one of them is just a matter of personnal preference for the developper or if they deserve different axes of productivity ? Does one of them should be applyed for some specific productivity needs or MS is just beeing kind offering three different flavours ? Should we consider CF as a sort of improvement over DBF or MF and thinking of it as a futur standard on wich spending a peculiar intelectual investment ... ? Is there a link showing a sort of synthetic table with un-passionate pros and cons for each approach, a little bit like for web-forms and MVC. Sorry for those who will find this question redondant. I know it is.

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  • Looking into Entity Framework Code First Migrations

    - by nikolaosk
    In this post I will introduce you to Code First Migrations, an Entity Framework feature introduced in version 4.3 back in February of 2012.I have extensively covered Entity Framework in this blog. Please find my other Entity Framework posts here .   Before the addition of Code First Migrations (4.1,4.2 versions), Code First database initialisation meant that Code First would create the database if it does not exist (the default behaviour - CreateDatabaseIfNotExists). The other pattern we could use is DropCreateDatabaseIfModelChanges which means that Entity Framework, will drop the database if it realises that model has changes since the last time it created the database.The final pattern is DropCreateDatabaseAlways which means that Code First will recreate the database every time one runs the application.That is of course fine for the development database but totally unacceptable and catastrophic when you have a production database. We cannot lose our data because of the work that Code First works.Migrations solve this problem.With migrations we can modify the database without completely dropping it.We can modify the database schema to reflect the changes to the model without losing data.In version EF 5.0 migrations are fully included and supported. I will demonstrate migrations with a hands-on example.Let me say a few words first about Entity Framework first. The .Net framework provides support for Object Relational Mappingthrough EF. So EF is a an ORM tool and it is now the main data access technology that microsoft works on. I use it quite extensively in my projects. Through EF we have many things out of the box provided for us. We have the automatic generation of SQL code.It maps relational data to strongly types objects.All the changes made to the objects in the memory are persisted in a transactional way back to the data store. You can find in this post an example on how to use the Entity Framework to retrieve data from an SQL Server Database using the "Database/Schema First" approach.In this approach we make all the changes at the database level and then we update the model with those changes. In this post you can see an example on how to use the "Model First" approach when working with ASP.Net and the Entity Framework.This model was firstly introduced in EF version 4.0 and we could start with a blank model and then create a database from that model.When we made changes to the model , we could recreate the database from the new model. The Code First approach is the more code-centric than the other two. Basically we write POCO classes and then we persist to a database using something called DBContext.Code First relies on DbContext. We create 2,3 classes (e.g Person,Product) with properties and then these classes interact with the DbContext class we can create a new database based upon our POCOS classes and have tables generated from those classes.We do not have an .edmx file in this approach.By using this approach we can write much easier unit tests.DbContext is a new context class and is smaller,lightweight wrapper for the main context class which is ObjectContext (Schema First and Model First).Let's move on to our hands-on example.I have installed VS 2012 Ultimate edition in my Windows 8 machine. 1)  Create an empty asp.net web application. Give your application a suitable name. Choose C# as the development language2) Add a new web form item in your application. Leave the default name.3) Create a new folder. Name it CodeFirst .4) Add a new item in your application, a class file. Name it Footballer.cs. This is going to be a simple POCO class.Place this class file in the CodeFirst folder.The code follows    public class Footballer     {         public int FootballerID { get; set; }         public string FirstName { get; set; }         public string LastName { get; set; }         public double Weight { get; set; }         public double Height { get; set; }              }5) We will have to add EF 5.0 to our project. Right-click on the project in the Solution Explorer and select Manage NuGet Packages... for it.In the window that will pop up search for Entity Framework and install it.Have a look at the picture below   If you want to find out if indeed EF version is 5.0 version is installed have a look at the References. Have a look at the picture below to see what you will see if you have installed everything correctly.Have a look at the picture below 6) Then we need to create a context class that inherits from DbContext.Add a new class to the CodeFirst folder.Name it FootballerDBContext.Now that we have the entity classes created, we must let the model know.I will have to use the DbSet<T> property.The code for this class follows     public class FootballerDBContext:DbContext     {         public DbSet<Footballer> Footballers { get; set; }             }    Do not forget to add  (using System.Data.Entity;) in the beginning of the class file 7) We must take care of the connection string. It is very easy to create one in the web.config.It does not matter that we do not have a database yet.When we run the DbContext and query against it , it will use a connection string in the web.config and will create the database based on the classes.I will use the name "FootballTraining" for the database.In my case the connection string inside the web.config, looks like this    <connectionStrings>    <add name="CodeFirstDBContext" connectionString="server=.;integrated security=true; database=FootballTraining" providerName="System.Data.SqlClient"/>                       </connectionStrings>8) Now it is time to create Linq to Entities queries to retrieve data from the database . Add a new class to your application in the CodeFirst folder.Name the file DALfootballer.csWe will create a simple public method to retrieve the footballers. The code for the class followspublic class DALfootballer     {         FootballerDBContext ctx = new FootballerDBContext();         public List<Footballer> GetFootballers()         {             var query = from player in ctx.Footballers select player;             return query.ToList();         }     } 9) Place a GridView control on the Default.aspx page and leave the default name.Add an ObjectDataSource control on the Default.aspx page and leave the default name. Set the DatasourceID property of the GridView control to the ID of the ObjectDataSource control.(DataSourceID="ObjectDataSource1" ). Let's configure the ObjectDataSource control. Click on the smart tag item of the ObjectDataSource control and select Configure Data Source. In the Wizzard that pops up select the DALFootballer class and then in the next step choose the GetFootballers() method.Click Finish to complete the steps of the wizzard.Build and Run your application.  10) Obviously you will not see any records coming back from your database, because we have not inserted anything. The database is created, though.Have a look at the picture below.  11) Now let's change the POCO class. Let's add a new property to the Footballer.cs class.        public int Age { get; set; } Build and run your application again. You will receive an error. Have a look at the picture below 12) That was to be expected.EF Code First Migrations is not activated by default. We have to activate them manually and configure them according to your needs. We will open the Package Manager Console from the Tools menu within Visual Studio 2012.Then we will activate the EF Code First Migration Features by writing the command “Enable-Migrations”.  Have a look at the picture below. This adds a new folder Migrations in our project. A new auto-generated class Configuration.cs is created.Another class is also created [CURRENTDATE]_InitialCreate.cs and added to our project.The Configuration.cs  is shown in the picture below. The [CURRENTDATE]_InitialCreate.cs is shown in the picture below  13) ??w we are ready to migrate the changes in the database. We need to run the Add-Migration Age command in Package Manager ConsoleAdd-Migration will scaffold the next migration based on changes you have made to your model since the last migration was created.In the Migrations folder, the file 201211201231066_Age.cs is created.Have a look at the picture below to see the newly generated file and its contents. Now we can run the Update-Database command in Package Manager Console .See the picture above.Code First Migrations will compare the migrations in our Migrations folder with the ones that have been applied to the database. It will see that the Age migration needs to be applied, and run it.The EFMigrations.CodeFirst.FootballeDBContext database is now updated to include the Age column in the Footballers table.Build and run your application.Everything will work fine now.Have a look at the picture below to see the migrations applied to our table. 14) We may want it to automatically upgrade the database (by applying any pending migrations) when the application launches.Let's add another property to our Poco class.          public string TShirtNo { get; set; }We want this change to migrate automatically to the database.We go to the Configuration.cs we enable automatic migrations.     public Configuration()        {            AutomaticMigrationsEnabled = true;        } In the Page_Load event handling routine we have to register the MigrateDatabaseToLatestVersion database initializer. A database initializer simply contains some logic that is used to make sure the database is setup correctly.   protected void Page_Load(object sender, EventArgs e)        {            Database.SetInitializer(new MigrateDatabaseToLatestVersion<FootballerDBContext, Configuration>());        } Build and run your application. It will work fine. Have a look at the picture below to see the migrations applied to our table in the database. Hope it helps!!!  

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  • aide --init show lots of errors

    - by newbie14
    I have a brand new centos 6.2 server. The first thing I did is yum -y install aide and then next I did aide --init. Below is a whole lot of errors I got.What does it means must I reinstall it? Or leave it ? /usr/sbin/prelink: /usr/sbin/lusermod: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/console-kit-daemon: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/NetworkManager: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/rtacct: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/tcpdump: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/dnsmasq: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/getsebool: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/ownership: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/modem-manager: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/pluginviewer: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/sasl2-shared-mechlist: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/ifdhandler: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/mklost+found: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/vpddecode: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/skdump: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/getpcaps: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/lpasswd: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/tmpwatch: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/ck-log-system-stop: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/alternatives: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/avahi-daemon: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/dump-acct: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/luseradd: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/nstat: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/efibootmgr: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/sasldblistusers2: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/e2freefrag: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/sa: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/lgroupadd: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/ss: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/dmidecode: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/sktest: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/fdformat: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/saslpasswd2: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/selinuxenabled: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/pppstats: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/wpa_supplicant: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/capsh: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/togglesebool: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/kppp: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/lgroupmod: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/cracklib-unpacker: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/getcap: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/avcstat: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/lnstat: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/filefrag: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/lid: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/bonobo-activation-sysconf: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/lockdev: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/mcelog: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/cifs.upcall: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/pcscd: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/brctl: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/logrotate: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/wpa_passphrase: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/pppdump: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/lsof: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/ck-log-system-start: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/setcap: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/rtkitctl: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/latencytop: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/wpa_cli: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process /usr/sbin/prelink: /usr/sbin/saned: at least one of file's dependencies has changed since prelinking Error on exit of prelink child process

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  • EF 6 Code First Many to many With Payload and self referencing many to many

    - by lesley86
    I Have the problem where i have a many to many relationship and on one of the tables there will be a self referencing many to many. So basically a school have zero or many groups and many groups can have 0 or many schools. The groups table will contain a parent child many to many with itself because a group can be a child of another group or it can have no children and that child can have a child, one child can also have many parents or a entity can have no parents. I created a mapping table with Payload to solvethe first many to many problem. code snippet public class School { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps } public class SchoolGroup { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps } public class SchoolGroupMap { public virtual School School public virtual SchoolGroup SchoolGroup } i Then tried modifying the code the following way for the the self referencing many to many public class SchoolGroup { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps public virtual ICollection<SchoolGroup> Parents public virtual ICollection<SchoolGroup> Children } I changed the context with has many and an auto mapping table (forgive me i have been trying so many things today i do not have the exact code). I received an error the properties on the classes must match. Can anyone help please. I want to do create navigation properties on the self referencing many to many. Also a seed example would be appreciated regards

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  • Entity Association Mapping with Code First Part 1 : Mapping Complex Types

    - by mortezam
    Last week the CTP5 build of the new Entity Framework Code First has been released by data team at Microsoft. Entity Framework Code-First provides a pretty powerful code-centric way to work with the databases. When it comes to associations, it brings ultimate flexibility. I’m a big fan of the EF Code First approach and am planning to explain association mapping with code first in a series of blog posts and this one is dedicated to Complex Types. If you are new to Code First approach, you can find a great walkthrough here. In order to build a solid foundation for our discussion, we will start by learning about some of the core concepts around the relationship mapping.   What is Mapping?Mapping is the act of determining how objects and their relationships are persisted in permanent data storage, in our case, relational databases. What is Relationship mapping?A mapping that describes how to persist a relationship (association, aggregation, or composition) between two or more objects. Types of RelationshipsThere are two categories of object relationships that we need to be concerned with when mapping associations. The first category is based on multiplicity and it includes three types: One-to-one relationships: This is a relationship where the maximums of each of its multiplicities is one. One-to-many relationships: Also known as a many-to-one relationship, this occurs when the maximum of one multiplicity is one and the other is greater than one. Many-to-many relationships: This is a relationship where the maximum of both multiplicities is greater than one. The second category is based on directionality and it contains two types: Uni-directional relationships: when an object knows about the object(s) it is related to but the other object(s) do not know of the original object. To put this in EF terminology, when a navigation property exists only on one of the association ends and not on the both. Bi-directional relationships: When the objects on both end of the relationship know of each other (i.e. a navigation property defined on both ends). How Object Relationships Are Implemented in POCO domain models?When the multiplicity is one (e.g. 0..1 or 1) the relationship is implemented by defining a navigation property that reference the other object (e.g. an Address property on User class). When the multiplicity is many (e.g. 0..*, 1..*) the relationship is implemented via an ICollection of the type of other object. How Relational Database Relationships Are Implemented? Relationships in relational databases are maintained through the use of Foreign Keys. A foreign key is a data attribute(s) that appears in one table and must be the primary key or other candidate key in another table. With a one-to-one relationship the foreign key needs to be implemented by one of the tables. To implement a one-to-many relationship we implement a foreign key from the “one table” to the “many table”. We could also choose to implement a one-to-many relationship via an associative table (aka Join table), effectively making it a many-to-many relationship. Introducing the ModelNow, let's review the model that we are going to use in order to implement Complex Type with Code First. It's a simple object model which consist of two classes: User and Address. Each user could have one billing address. The Address information of a User is modeled as a separate class as you can see in the UML model below: In object-modeling terms, this association is a kind of aggregation—a part-of relationship. Aggregation is a strong form of association; it has some additional semantics with regard to the lifecycle of objects. In this case, we have an even stronger form, composition, where the lifecycle of the part is fully dependent upon the lifecycle of the whole. Fine-grained domain models The motivation behind this design was to achieve Fine-grained domain models. In crude terms, fine-grained means “more classes than tables”. For example, a user may have both a billing address and a home address. In the database, you may have a single User table with the columns BillingStreet, BillingCity, and BillingPostalCode along with HomeStreet, HomeCity, and HomePostalCode. There are good reasons to use this somewhat denormalized relational model (performance, for one). In our object model, we can use the same approach, representing the two addresses as six string-valued properties of the User class. But it’s much better to model this using an Address class, where User has the BillingAddress and HomeAddress properties. This object model achieves improved cohesion and greater code reuse and is more understandable. Complex Types: Splitting a Table Across Multiple Types Back to our model, there is no difference between this composition and other weaker styles of association when it comes to the actual C# implementation. But in the context of ORM, there is a big difference: A composed class is often a candidate Complex Type. But C# has no concept of composition—a class or property can’t be marked as a composition. The only difference is the object identifier: a complex type has no individual identity (i.e. no AddressId defined on Address class) which make sense because when it comes to the database everything is going to be saved into one single table. How to implement a Complex Types with Code First Code First has a concept of Complex Type Discovery that works based on a set of Conventions. The convention is that if Code First discovers a class where a primary key cannot be inferred, and no primary key is registered through Data Annotations or the fluent API, then the type will be automatically registered as a complex type. Complex type detection also requires that the type does not have properties that reference entity types (i.e. all the properties must be scalar types) and is not referenced from a collection property on another type. Here is the implementation: public class User{    public int UserId { get; set; }    public string FirstName { get; set; }    public string LastName { get; set; }    public string Username { get; set; }    public Address Address { get; set; }} public class Address {     public string Street { get; set; }     public string City { get; set; }            public string PostalCode { get; set; }        }public class EntityMappingContext : DbContext {     public DbSet<User> Users { get; set; }        } With code first, this is all of the code we need to write to create a complex type, we do not need to configure any additional database schema mapping information through Data Annotations or the fluent API. Database SchemaThe mapping result for this object model is as follows: Limitations of this mappingThere are two important limitations to classes mapped as Complex Types: Shared references is not possible: The Address Complex Type doesn’t have its own database identity (primary key) and so can’t be referred to by any object other than the containing instance of User (e.g. a Shipping class that also needs to reference the same User Address). No elegant way to represent a null reference There is no elegant way to represent a null reference to an Address. When reading from database, EF Code First always initialize Address object even if values in all mapped columns of the complex type are null. This means that if you store a complex type object with all null property values, EF Code First returns a initialized complex type when the owning entity object is retrieved from the database. SummaryIn this post we learned about fine-grained domain models which complex type is just one example of it. Fine-grained is fully supported by EF Code First and is known as the most important requirement for a rich domain model. Complex type is usually the simplest way to represent one-to-one relationships and because the lifecycle is almost always dependent in such a case, it’s either an aggregation or a composition in UML. In the next posts we will revisit the same domain model and will learn about other ways to map a one-to-one association that does not have the limitations of the complex types. References ADO.NET team blog Mapping Objects to Relational Databases Java Persistence with Hibernate

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  • SQL SERVER – SSIS Parameters in Parent-Child ETL Architectures – Notes from the Field #040

    - by Pinal Dave
    [Notes from Pinal]: SSIS is very well explored subject, however, there are so many interesting elements when we read, we learn something new. A similar concept has been Parent-Child ETL architecture’s relationship in SSIS. Linchpin People are database coaches and wellness experts for a data driven world. In this 40th episode of the Notes from the Fields series database expert Tim Mitchell (partner at Linchpin People) shares very interesting conversation related to how to understand SSIS Parameters in Parent-Child ETL Architectures. In this brief Notes from the Field post, I will review the use of SSIS parameters in parent-child ETL architectures. A very common design pattern used in SQL Server Integration Services is one I call the parent-child pattern.  Simply put, this is a pattern in which packages are executed by other packages.  An ETL infrastructure built using small, single-purpose packages is very often easier to develop, debug, and troubleshoot than large, monolithic packages.  For a more in-depth look at parent-child architectures, check out my earlier blog post on this topic. When using the parent-child design pattern, you will frequently need to pass values from the calling (parent) package to the called (child) package.  In older versions of SSIS, this process was possible but not necessarily simple.  When using SSIS 2005 or 2008, or even when using SSIS 2012 or 2014 in package deployment mode, you would have to create package configurations to pass values from parent to child packages.  Package configurations, while effective, were not the easiest tool to work with.  Fortunately, starting with SSIS in SQL Server 2012, you can now use package parameters for this purpose. In the example I will use for this demonstration, I’ll create two packages: one intended for use as a child package, and the other configured to execute said child package.  In the parent package I’m going to build a for each loop container in SSIS, and use package parameters to pass in a value – specifically, a ClientID – for each iteration of the loop.  The child package will be executed from within the for each loop, and will create one output file for each client, with the source query and filename dependent on the ClientID received from the parent package. Configuring the Child and Parent Packages When you create a new package, you’ll see the Parameters tab at the package level.  Clicking over to that tab allows you to add, edit, or delete package parameters. As shown above, the sample package has two parameters.  Note that I’ve set the name, data type, and default value for each of these.  Also note the column entitled Required: this allows me to specify whether the parameter value is optional (the default behavior) or required for package execution.  In this example, I have one parameter that is required, and the other is not. Let’s shift over to the parent package briefly, and demonstrate how to supply values to these parameters in the child package.  Using the execute package task, you can easily map variable values in the parent package to parameters in the child package. The execute package task in the parent package, shown above, has the variable vThisClient from the parent package mapped to the pClientID parameter shown earlier in the child package.  Note that there is no value mapped to the child package parameter named pOutputFolder.  Since this parameter has the Required property set to False, we don’t have to specify a value for it, which will cause that parameter to use the default value we supplied when designing the child pacakge. The last step in the parent package is to create the for each loop container I mentioned earlier, and place the execute package task inside it.  I’m using an object variable to store the distinct client ID values, and I use that as the iterator for the loop (I describe how to do this more in depth here).  For each iteration of the loop, a different client ID value will be passed into the child package parameter. The final step is to configure the child package to actually do something meaningful with the parameter values passed into it.  In this case, I’ve modified the OleDB source query to use the pClientID value in the WHERE clause of the query to restrict results for each iteration to a single client’s data.  Additionally, I’ll use both the pClientID and pOutputFolder parameters to dynamically build the output filename. As shown, the pClientID is used in the WHERE clause, so we only get the current client’s invoices for each iteration of the loop. For the flat file connection, I’m setting the Connection String property using an expression that engages both of the parameters for this package, as shown above. Parting Thoughts There are many uses for package parameters beyond a simple parent-child design pattern.  For example, you can create standalone packages (those not intended to be used as a child package) and still use parameters.  Parameter values may be supplied to a package directly at runtime by a SQL Server Agent job, through the command line (via dtexec.exe), or through T-SQL. Also, you can also have project parameters as well as package parameters.  Project parameters work in much the same way as package parameters, but the parameters apply to all packages in a project, not just a single package. Conclusion Of the numerous advantages of using catalog deployment model in SSIS 2012 and beyond, package parameters are near the top of the list.  Parameters allow you to easily share values from parent to child packages, enabling more dynamic behavior and better code encapsulation. If you want me to take a look at your server and its settings, or if your server is facing any issue we can Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Nature of Lock is child table while deletion(sql server)

    - by Mubashar Ahmad
    Dear Devs From couple of days i am thinking of a following scenario Consider I have 2 tables with parent child relationship of kind one-to-many. On removal of parent row i have to delete the rows in child those are related to parents. simple right? i have to make a transaction scope to do above operation i can do this as following; (its psuedo code but i am doing this in c# code using odbc connection and database is sql server) begin transaction(read committed) Read all child where child.fk = p1 foreach(child) delete child where child.pk = cx delete parent where parent.pk = p1 commit trans OR begin transaction(read committed) delete all child where child.fk = p1 delete parent where parent.pk = p1 commit trans Now there are couple of questions in my mind Which one of above is better to use specially considering a scenario of real time system where thousands of other operations(select/update/delete/insert) are being performed within a span of seconds. does it ensure that no new child with child.fk = p1 will be added until transaction completes? If yes for 2nd question then how it ensures? do it take the table level locks or what. Is there any kind of Index locking supported by sql server if yes what it does and how it can be used. Regards Mubashar

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  • Improving first person camera and implementing third person camera

    - by brainydexter
    I want to improve upon my first person camera implementation and extend it to, so the user can toggle between third person/first person view. My current setup: draw():: glPushMatrix(); m_pCamera->ApplyCameraTransform(); // Render gameObjects glPopMatrix(); Camera is strongly coupled to the player, so much so, that it is a friend of player. This is what the Camera::ApplyCameraTransform looks like: glm::mat4 l_TransformationMatrix; m_pPlayer->m_pTransformation->GetTransformation(l_TransformationMatrix, false); l_TransformationMatrix = glm::core::function::matrix::inverse(l_TransformationMatrix); glMultMatrixf(glm::value_ptr(l_TransformationMatrix)); So, I take the player's transformation matrix and invert it to yield First person camera view. Since, Third person camera view is just a 'translated' first person view behind the player; what would be a good way to improve upon this (keeping in mind that I will be extending it to Third person camera as well. Thanks

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  • code first CTP5 error message

    - by user482833
    I get the following error message with a new project I have set using code first CTP5. Can't find anything on the web about it. Has anyone encountered this error message? The context cannot be used while the model is being created. This occurs the first time my database context is called (code below): using (StaffData context = new StaffData()) { return context.Employees.Count(e = e.EmployeeReference) == 1; } At this point the database has not been created. I have a database initialiser DropCreateDatabaseIfModelChanges which I set in app_start.

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  • How do I fork a maximum of 5 child processes of the parent at any one time?

    - by bstullkid
    I have the following code, which I'm trying to only allow a maximum of 5 children to run at a time, but I can't figure out how to decrement the child count when a child exits. struct { char *s1; char *s2; } s[] = { {"one", "oneB"}, {"two", "twoB"}, {"three", "thr4eeB"}, {"asdf", "3th43reeB"}, {"asdfasdf", "thr33eeB"}, {"asdfasdfasdf", "thdfdreeB"}, {"af3c3", "thrasdfeeB"}, {"fec33", "threfdeB"}, {NULL, NULL} }; int main(int argc, char *argv[]) { int i, im5, children = 0; int pid = fork(); for (i = 0; s[i].s2; i++) { im5 = 0; switch (pid) { case -1: { printf("Error\n"); exit(255); } case 0: { printf("%s -> %s\n", s[i].s1, s[i].s2); if (i==5) im5 = 1; printf("%d\n", im5); sleep(i); exit(1); } default: { // Here is where I need to sleep the parent until chilren < 5 // so where do i decrement children so that it gets modified in the parent process? while(children > 5) sleep(1); children++; pid = fork(); } } } return 1; }

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  • Compiling a program with a legacy version of gcc

    - by wyatt
    This is probably a very difficult problem to troubleshoot with the information I can practically provide, but I'm hoping someone might be able to at least point me in a possible direction. I'm trying to install HTK (http://htk.eng.cam.ac.uk/), which, according to this page needs to be installed using gcc 3.4. Their method of implementing backwards compatibility: #yum install compat-gcc-34-c++ compat-gcc-34 won't work for me as I'm running Ubuntu (On that note, I take it I can't simply install YUM and the subsequent package, since it's an entirely different distro, but if I'm wrong I'd love to hear it). I instead installed two versions of gcc 3.4 - 3.4.0 and 3.4.6 using instructions from this site. I then added the lines suggested by that page to the top of the makefile (on this note, what's the difference between makefile and makefile.in? I tried adding the lines to the top of both files regardless), both for version 3.4.0 and 3.4.6, but both failed. I also tried, on the off-chance, compiling it with my current version (4.4.1), but that also failed. I got the errors: (cd HTKLib && make HTKLib.a) \ || case "" in k) fail=yes;; ) exit 1;; esac; make1: Entering directory /home/charles/bin/htk-3.4/HTKLib' gcc -ansi -D_SVID_SOURCE -DOSS_AUDIO -D'ARCH="i686"' -Wall -Wno-switch -g -O2 -I. -c -o HGraf.o HGraf.c HGraf.c:73:77: error: X11/Xlib.h: No such file or directory HGraf.c:74:23: error: X11/Xutil.h: No such file or directory HGraf.c:75:21: error: X11/Xos.h: No such file or directory HGraf.c:77:27: error: X11/keysymdef.h: No such file or directory HGraf.c:87: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token HGraf.c:88: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘rootW’ HGraf.c:91: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘theCmap’ HGraf.c:92: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘theGC’ HGraf.c:93: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘gcs’ HGraf.c:95: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token HGraf.c:96: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘report’ HGraf.c:97: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘hints’ HGraf.c:111: error: ‘GXcopy’ undeclared here (not in a function) HGraf.c:111: error: ‘GXor’ undeclared here (not in a function) HGraf.c:111: error: ‘GXxor’ undeclared here (not in a function) HGraf.c:111: error: ‘GXinvert’ undeclared here (not in a function) HGraf.c:151: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token HGraf.c: In function ‘InstallFonts’: HGraf.c:164: error: ‘FontInfo’ undeclared (first use in this function) HGraf.c:164: error: (Each undeclared identifier is reported only once HGraf.c:164: error: for each function it appears in.) HGraf.c:164: warning: implicit declaration of function ‘XLoadQueryFont’ HGraf.c:164: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:167: error: ‘DefaultFont’ undeclared (first use in this function) HGraf.c: At top level: HGraf.c:176: error: expected ‘)’ before ‘*’ token HGraf.c: In function ‘HGetEvent’: HGraf.c:219: error: ‘XEvent’ undeclared (first use in this function) HGraf.c:219: error: expected ‘;’ before ‘xev’ HGraf.c:223: warning: implicit declaration of function ‘XFlush’ HGraf.c:223: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:225: warning: implicit declaration of function ‘XEventsQueued’ HGraf.c:225: error: ‘QueuedAfterFlush’ undeclared (first use in this function) HGraf.c:226: warning: implicit declaration of function ‘XNextEvent’ HGraf.c:226: error: ‘xev’ undeclared (first use in this function) HGraf.c:228: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:230: error: ‘ButtonPress’ undeclared (first use in this function) HGraf.c:235: error: ‘ButtonRelease’ undeclared (first use in this function) HGraf.c:240: error: ‘MotionNotify’ undeclared (first use in this function) HGraf.c:245: error: ‘KeyPress’ undeclared (first use in this function) HGraf.c:249: warning: implicit declaration of function ‘DecodeKeyPress’ HGraf.c:251: error: ‘KeyRelease’ undeclared (first use in this function) HGraf.c:257: error: ‘Expose’ undeclared (first use in this function) HGraf.c: In function ‘HEventsPending’: HGraf.c:281: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:281: error: ‘QueuedAfterFlush’ undeclared (first use in this function) HGraf.c: In function ‘HMousePos’: HGraf.c:288: error: ‘Window’ undeclared (first use in this function) HGraf.c:288: error: expected ‘;’ before ‘root’ HGraf.c:293: warning: implicit declaration of function ‘XQueryPointer’ HGraf.c:293: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:293: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:293: error: ‘root’ undeclared (first use in this function) HGraf.c:293: error: ‘child’ undeclared (first use in this function) HGraf.c: In function ‘InstallColours’: HGraf.c:311: error: ‘XColor’ undeclared (first use in this function) HGraf.c:311: error: expected ‘;’ before ‘greyDef’ HGraf.c:317: warning: implicit declaration of function ‘XParseColor’ HGraf.c:317: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:317: error: ‘theCmap’ undeclared (first use in this function) HGraf.c:317: error: ‘colourDef’ undeclared (first use in this function) HGraf.c:320: warning: implicit declaration of function ‘XAllocColor’ HGraf.c:334: error: ‘whiteDef’ undeclared (first use in this function) HGraf.c:334: warning: implicit declaration of function ‘XQueryColor’ HGraf.c:335: error: ‘blackDef’ undeclared (first use in this function) HGraf.c:341: error: ‘greyDef’ undeclared (first use in this function) HGraf.c: In function ‘HSetColour’: HGraf.c:361: warning: implicit declaration of function ‘XSetForeground’ HGraf.c:361: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:361: error: ‘gcs’ undeclared (first use in this function) HGraf.c: In function ‘HSetGrey’: HGraf.c:370: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:370: error: ‘gcs’ undeclared (first use in this function) HGraf.c: In function ‘HDrawLines’: HGraf.c:388: warning: implicit declaration of function ‘XDrawLines’ HGraf.c:388: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:388: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:388: error: ‘theGC’ undeclared (first use in this function) HGraf.c:388: error: ‘XPoint’ undeclared (first use in this function) HGraf.c:388: error: expected expression before ‘)’ token HGraf.c: In function ‘HDrawRectangle’: HGraf.c:395: warning: implicit declaration of function ‘XDrawRectangle’ HGraf.c:395: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:395: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:395: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HFillRectangle’: HGraf.c:402: warning: implicit declaration of function ‘XFillRectangle’ HGraf.c:402: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:402: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:402: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HDrawLine’: HGraf.c:408: warning: implicit declaration of function ‘XDrawLine’ HGraf.c:408: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:408: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:408: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HFillPolygon’: HGraf.c:414: warning: implicit declaration of function ‘XFillPolygon’ HGraf.c:414: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:414: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:414: error: ‘theGC’ undeclared (first use in this function) HGraf.c:414: error: ‘XPoint’ undeclared (first use in this function) HGraf.c:414: error: expected expression before ‘)’ token HGraf.c: In function ‘HDrawArc’: HGraf.c:427: warning: implicit declaration of function ‘XDrawArc’ HGraf.c:427: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:427: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:427: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HFillArc’: HGraf.c:440: warning: implicit declaration of function ‘XFillArc’ HGraf.c:440: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:440: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:440: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HPrintf’: HGraf.c:451: warning: implicit declaration of function ‘XDrawString’ HGraf.c:451: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:451: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:451: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HCopyArea’: HGraf.c:457: warning: implicit declaration of function ‘XCopyArea’ HGraf.c:457: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:457: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:457: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HPlotVector’: HGraf.c:476: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:476: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:476: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HSetFontSize’: HGraf.c:490: error: ‘CurrentFont’ undeclared (first use in this function) HGraf.c:490: error: ‘DefaultFont’ undeclared (first use in this function) HGraf.c:499: error: ‘FontInfo’ undeclared (first use in this function) HGraf.c:502: warning: implicit declaration of function ‘XSetFont’ HGraf.c:502: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:502: error: ‘gcs’ undeclared (first use in this function) HGraf.c: In function ‘HSetLineWidth’: HGraf.c:511: warning: implicit declaration of function ‘XSetLineAttributes’ HGraf.c:511: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:511: error: ‘gcs’ undeclared (first use in this function) HGraf.c:511: error: ‘LineSolid’ undeclared (first use in this function) HGraf.c:511: error: ‘JoinRound’ undeclared (first use in this function) HGraf.c:511: error: ‘FillSolid’ undeclared (first use in this function) HGraf.c: In function ‘HSetXMode’: HGraf.c:517: error: ‘theGC’ undeclared (first use in this function) HGraf.c:517: error: ‘gcs’ undeclared (first use in this function) HGraf.c: In function ‘CentreX’: HGraf.c:523: warning: implicit declaration of function ‘XTextWidth’ HGraf.c:523: error: ‘CurrentFont’ undeclared (first use in this function) HGraf.c: In function ‘CentreY’: HGraf.c:529: error: ‘CurrentFont’ undeclared (first use in this function) HGraf.c: In function ‘HTextWidth’: HGraf.c:535: error: ‘CurrentFont’ undeclared (first use in this function) HGraf.c: In function ‘HTextHeight’: HGraf.c:541: error: ‘CurrentFont’ undeclared (first use in this function) HGraf.c: In function ‘HDrawImage’: HGraf.c:550: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token HGraf.c:550: error: ‘xi’ undeclared (first use in this function) HGraf.c:557: warning: implicit declaration of function ‘XDestroyImage’ HGraf.c:558: warning: implicit declaration of function ‘XGetImage’ HGraf.c:558: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:558: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:558: error: ‘AllPlanes’ undeclared (first use in this function) HGraf.c:558: error: ‘XYPixmap’ undeclared (first use in this function) HGraf.c:562: warning: implicit declaration of function ‘XPutPixel’ HGraf.c:564: warning: implicit declaration of function ‘XPutImage’ HGraf.c:564: error: ‘theGC’ undeclared (first use in this function) HGraf.c: In function ‘HFlush’: HGraf.c:570: error: ‘theDisp’ undeclared (first use in this function) HGraf.c: In function ‘InitGCs’: HGraf.c:780: error: ‘XGCValues’ undeclared (first use in this function) HGraf.c:780: error: expected ‘;’ before ‘values’ HGraf.c:783: error: ‘GCLineWidth’ undeclared (first use in this function) HGraf.c:783: error: ‘GCFunction’ undeclared (first use in this function) HGraf.c:783: error: ‘GCForeground’ undeclared (first use in this function) HGraf.c:785: error: ‘values’ undeclared (first use in this function) HGraf.c:788: error: ‘gcs’ undeclared (first use in this function) HGraf.c:788: warning: implicit declaration of function ‘XCreateGC’ HGraf.c:788: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:788: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:790: error: ‘GCPlaneMask’ undeclared (first use in this function) HGraf.c: In function ‘InitGlobals’: HGraf.c:800: warning: implicit declaration of function ‘DefaultScreen’ HGraf.c:800: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:801: error: ‘theCmap’ undeclared (first use in this function) HGraf.c:801: warning: implicit declaration of function ‘DefaultColormap’ HGraf.c:802: error: ‘rootW’ undeclared (first use in this function) HGraf.c:802: warning: implicit declaration of function ‘RootWindow’ HGraf.c:803: error: ‘theGC’ undeclared (first use in this function) HGraf.c:803: warning: implicit declaration of function ‘DefaultGC’ HGraf.c:804: error: ‘theVisual’ undeclared (first use in this function) HGraf.c:804: warning: implicit declaration of function ‘DefaultVisual’ HGraf.c:805: warning: implicit declaration of function ‘DisplayCells’ HGraf.c:806: warning: implicit declaration of function ‘DisplayWidth’ HGraf.c:807: warning: implicit declaration of function ‘DisplayHeight’ HGraf.c:808: warning: implicit declaration of function ‘DisplayPlanes’ HGraf.c:809: warning: implicit declaration of function ‘WhitePixel’ HGraf.c:810: warning: implicit declaration of function ‘BlackPixel’ HGraf.c: In function ‘MakeXGraf’: HGraf.c:817: error: ‘Window’ undeclared (first use in this function) HGraf.c:817: error: expected ‘;’ before ‘window’ HGraf.c:818: error: ‘XSetWindowAttributes’ undeclared (first use in this function) HGraf.c:818: error: expected ‘;’ before ‘setwinattr’ HGraf.c:823: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:823: warning: implicit declaration of function ‘XOpenDisplay’ HGraf.c:824: warning: implicit declaration of function ‘XDisplayName’ HGraf.c:828: error: ‘parent’ undeclared (first use in this function) HGraf.c:829: error: ‘window’ undeclared (first use in this function) HGraf.c:829: warning: implicit declaration of function ‘XCreateSimpleWindow’ HGraf.c:831: error: ‘CWBackingStore’ undeclared (first use in this function) HGraf.c:831: error: ‘setwinattr’ undeclared (first use in this function) HGraf.c:831: error: ‘WhenMapped’ undeclared (first use in this function) HGraf.c:832: warning: implicit declaration of function ‘XChangeWindowAttributes’ HGraf.c:834: error: ‘hints’ undeclared (first use in this function) HGraf.c:834: error: ‘PPosition’ undeclared (first use in this function) HGraf.c:834: error: ‘PSize’ undeclared (first use in this function) HGraf.c:834: error: ‘PMaxSize’ undeclared (first use in this function) HGraf.c:834: error: ‘PMinSize’ undeclared (first use in this function) HGraf.c:841: warning: implicit declaration of function ‘XSetStandardProperties’ HGraf.c:841: error: ‘None’ undeclared (first use in this function) HGraf.c:843: warning: implicit declaration of function ‘XSelectInput’ HGraf.c:843: error: ‘ExposureMask’ undeclared (first use in this function) HGraf.c:843: error: ‘KeyPressMask’ undeclared (first use in this function) HGraf.c:843: error: ‘ButtonPressMask’ undeclared (first use in this function) HGraf.c:844: error: ‘ButtonReleaseMask’ undeclared (first use in this function) HGraf.c:844: error: ‘PointerMotionHintMask’ undeclared (first use in this function) HGraf.c:844: error: ‘PointerMotionMask’ undeclared (first use in this function) HGraf.c:845: warning: implicit declaration of function ‘XMapWindow’ HGraf.c:845: error: ‘theWindow’ undeclared (first use in this function) HGraf.c:850: error: ‘report’ undeclared (first use in this function) HGraf.c:851: error: ‘Expose’ undeclared (first use in this function) HGraf.c:852: warning: implicit declaration of function ‘XSendEvent’ HGraf.c:852: error: ‘False’ undeclared (first use in this function) HGraf.c: In function ‘TermHGraf’: HGraf.c:861: error: ‘theDisp’ undeclared (first use in this function) HGraf.c:862: warning: implicit declaration of function ‘XCloseDisplay’ make[1]: *** [HGraf.o] Error 1 make[1]: Leaving directory/home/charles/bin/htk-3.4/HTKLib' make: ** [HTKLib/HTKLib.a] Error 1 Thank you for any help you can provide.

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  • Custom TableViewCell with TextField and first responder

    - by Robb
    I have a custom TableView cell that contains a TextField and I want it to become the first responder as soon as the view is shown but [textcell.textfield becomeFirstResponder] does not work. I know it's because it's a custom cell in another class and I even tried it there and it didn't work. Anyone know how to pull this off? Thanks...

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  • Looking into Enum Support in Entity Framework 5.0 Code First

    - by nikolaosk
    In this post I will show you with a hands-on demo the enum support that is available in Visual Studio 2012, .Net Framework 4.5 and Entity Framework 5.0. You can have a look at this post to learn about the support of multilple diagrams per model that exists in Entity Framework 5.0. We will demonstrate this with a step by step example. I will use Visual Studio 2012 Ultimate. You can also use Visual Studio 2012 Express Edition. Before I move on to the actual demo I must say that in EF 5.0 an enumeration can have the following types. Byte Int16 Int32 Int64 Sbyte Obviously I cannot go into much detail on what EF is and what it does. I will give again a short introduction.The .Net framework provides support for Object Relational Mapping through EF. So EF is a an ORM tool and it is now the main data access technology that microsoft works on. I use it quite extensively in my projects. Through EF we have many things out of the box provided for us. We have the automatic generation of SQL code.It maps relational data to strongly types objects.All the changes made to the objects in the memory are persisted in a transactional way back to the data store. You can find in this post an example on how to use the Entity Framework to retrieve data from an SQL Server Database using the "Database/Schema First" approach. In this approach we make all the changes at the database level and then we update the model with those changes. In this post you can see an example on how to use the "Model First" approach when working with ASP.Net and the Entity Framework. This model was firstly introduced in EF version 4.0 and we could start with a blank model and then create a database from that model.When we made changes to the model , we could recreate the database from the new model. You can search in my blog, because I have posted many posts regarding ASP.Net and EF. I assume you have a working knowledge of C# and know a few things about EF. The Code First approach is the more code-centric than the other two. Basically we write POCO classes and then we persist to a database using something called DBContext. Code First relies on DbContext. We create 2,3 classes (e.g Person,Product) with properties and then these classes interact with the DbContext class. We can create a new database based upon our POCOS classes and have tables generated from those classes.We do not have an .edmx file in this approach.By using this approach we can write much easier unit tests. DbContext is a new context class and is smaller,lightweight wrapper for the main context class which is ObjectContext (Schema First and Model First). Let's begin building our sample application. 1) Launch Visual Studio. Create an ASP.Net Empty Web application. Choose an appropriate name for your application. 2) Add a web form, default.aspx page to the application. 3) Now we need to make sure the Entity Framework is included in our project. Go to Solution Explorer, right-click on the project name.Then select Manage NuGet Packages...In the Manage NuGet Packages dialog, select the Online tab and choose the EntityFramework package.Finally click Install. Have a look at the picture below   4) Create a new folder. Name it CodeFirst . 5) Add a new item in your application, a class file. Name it Footballer.cs. This is going to be a simple POCO class.Place it in the CodeFirst folder. The code follows public class Footballer { public int FootballerID { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public double Weight { get; set; } public double Height { get; set; } public DateTime JoinedTheClub { get; set; } public int Age { get; set; } public List<Training> Trainings { get; set; } public FootballPositions Positions { get; set; } }    Now I am going to define my enum values in the same class file, Footballer.cs    public enum FootballPositions    {        Defender,        Midfielder,        Striker    } 6) Now we need to create the Training class. Add a new class to your application and place it in the CodeFirst folder.The code for the class follows.     public class Training     {         public int TrainingID { get; set; }         public int TrainingDuration { get; set; }         public string TrainingLocation { get; set; }     }   7) Then we need to create a context class that inherits from DbContext.Add a new class to the CodeFirst folder.Name it FootballerDBContext.Now that we have the entity classes created, we must let the model know.I will have to use the DbSet<T> property.The code for this class follows       public class FootballerDBContext:DbContext     {         public DbSet<Footballer> Footballers { get; set; }         public DbSet<Training> Trainings { get; set; }     } Do not forget to add  (using System.Data.Entity;) in the beginning of the class file 8) We must take care of the connection string. It is very easy to create one in the web.config.It does not matter that we do not have a database yet.When we run the DbContext and query against it,it will use a connection string in the web.config and will create the database based on the classes. In my case the connection string inside the web.config, looks like this      <connectionStrings>    <add name="CodeFirstDBContext"  connectionString="server=.\SqlExpress;integrated security=true;"  providerName="System.Data.SqlClient"/>                       </connectionStrings>   9) Now it is time to create Linq to Entities queries to retrieve data from the database . Add a new class to your application in the CodeFirst folder.Name the file DALfootballer.cs We will create a simple public method to retrieve the footballers. The code for the class follows public class DALfootballer     {         FootballerDBContext ctx = new FootballerDBContext();         public List<Footballer> GetFootballers()         {             var query = from player in ctx.Footballers where player.FirstName=="Jamie" select player;             return query.ToList();         }     }   10) Place a GridView control on the Default.aspx page and leave the default name.Add an ObjectDataSource control on the Default.aspx page and leave the default name. Set the DatasourceID property of the GridView control to the ID of the ObjectDataSource control.(DataSourceID="ObjectDataSource1" ). Let's configure the ObjectDataSource control. Click on the smart tag item of the ObjectDataSource control and select Configure Data Source. In the Wizzard that pops up select the DALFootballer class and then in the next step choose the GetFootballers() method.Click Finish to complete the steps of the wizzard. Build your application.  11)  Let's create an Insert method in order to insert data into the tables. I will create an Insert() method and for simplicity reasons I will place it in the Default.aspx.cs file. private void Insert()        {            var footballers = new List<Footballer>            {                new Footballer {                                 FirstName = "Steven",LastName="Gerrard", Height=1.85, Weight=85,Age=32, JoinedTheClub=DateTime.Parse("12/12/1999"),Positions=FootballPositions.Midfielder,                Trainings = new List<Training>                             {                                     new Training {TrainingDuration = 3, TrainingLocation="MelWood"},                    new Training {TrainingDuration = 2, TrainingLocation="Anfield"},                    new Training {TrainingDuration = 2, TrainingLocation="MelWood"},                }                            },                            new Footballer {                                  FirstName = "Jamie",LastName="Garragher", Height=1.89, Weight=89,Age=34, JoinedTheClub=DateTime.Parse("12/02/2000"),Positions=FootballPositions.Defender,                Trainings = new List<Training>                                             {                                 new Training {TrainingDuration = 3, TrainingLocation="MelWood"},                new Training {TrainingDuration = 5, TrainingLocation="Anfield"},                new Training {TrainingDuration = 6, TrainingLocation="Anfield"},                }                           }                    };            footballers.ForEach(foot => ctx.Footballers.Add(foot));            ctx.SaveChanges();        }   12) In the Page_Load() event handling routine I called the Insert() method.        protected void Page_Load(object sender, EventArgs e)        {                   Insert();                }  13) Run your application and you will see that the following result,hopefully. You can see clearly that the data is returned along with the enum value.  14) You must have also a look at the database.Launch SSMS and see the database and its objects (data) created from EF Code First.Have a look at the picture below. Hopefully now you have seen the support that exists in EF 5.0 for enums.Hope it helps !!!

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  • How to include a child object's child object in Entity Framework 5

    - by Brendan Vogt
    I am using Entity Framework 5 code first and ASP.NET MVC 3. I am struggling to get a child object's child object to populate. Below are my classes.. Application class; public class Application { // Partial list of properties public virtual ICollection<Child> Children { get; set; } } Child class: public class Child { // Partial list of properties public int ChildRelationshipTypeId { get; set; } public virtual ChildRelationshipType ChildRelationshipType { get; set; } } ChildRelationshipType class: public class ChildRelationshipType { public int Id { get; set; } public string Name { get; set; } } Part of GetAll method in the repository to return all the applications: return DatabaseContext.Applications .Include("Children"); The Child class contains a reference to the ChildRelationshipType class. To work with an application's children I would have something like this: foreach (Child child in application.Children) { string childName = child.ChildRelationshipType.Name; } I get an error here that the object context is already closed. How do I specify that each child object must include the ChildRelationshipType object like what I did above?

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  • Calculating a child Position, Rotation and Scale values?

    - by Sergio Plascencia
    I am making my own game editor(just for fun) anyway I have problem that I had several days trying to resolve but I have been unsuccessful. Here goes... I have an object "A": Position: (3,3,3), Rotation: (45,10,0), Scale(1,2,2.5) And an object "B": Position: (1,1,1), Rotation: (10,34,18), Scale(1.5,2,1) I now make a parent/child relationship. "B" is a child of "A": A |--B When I do the relationship I need to re-calculate the Child("B") Position, Rotation and Scale such that it maintains its current position, rotation and scale(Location in world). So for child position "B" it would now be (-2, -2, -2) since now "A" it is center and (-2, -2, -2) will keep the object in its same position. I think I got the Position and scale figure out, but rotation I cant. So I was trying to figure out what to do and what I did is opened Unity and run the same example and I did noticed that when making an abject a child object the child object did not moved at all but had its Position, Rotation and Scale values changed(Related to the parent). For example: Unity (Parent Object "A"): Position: (0,0,0) Rotation: (45,10,0) Scale: (1,1,1) Unity (Child Object "B"): Position: (0,0,0) Rotation: (0,0,0) Scale: (1,1,1) When making it a parent child relation("B" is a child of "A") the child object("B") in its Rotation values now has: X: -44.13605 Y: -14.00195 Z: 9.851074 If I plug the same values to my editor(To the child "B" rotation X, Y, Z values) the object does not move at all. So I basically need to know how did Unity arrive at those rotation values for the child(What are the calculations?). If you can help and put all the equations for the Position, Rotation or Scale then I can double check I am doing it correctly but with the Rotation I really need help. Thanks!

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  • Using Entity Framework (code first) migrations in production

    - by devdigital
    I'm just looking into using EF migrations for our project, and in particular for performing schema changes in production between releases. I can see that generating SQL (delta) script files is an option, but is there no way of running the migrations programmatically on app start up? Will I instead need to add each delta script to the solution and write my own framework to apply them in order (from the current version to the latest) on bootstrap?

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  • Pluggable Rules for Entity Framework Code First

    - by Ricardo Peres
    Suppose you want a system that lets you plug custom validation rules on your Entity Framework context. The rules would control whether an entity can be saved, updated or deleted, and would be implemented in plain .NET. Yes, I know I already talked about plugable validation in Entity Framework Code First, but this is a different approach. An example API is in order, first, a ruleset, which will hold the collection of rules: 1: public interface IRuleset : IDisposable 2: { 3: void AddRule<T>(IRule<T> rule); 4: IEnumerable<IRule<T>> GetRules<T>(); 5: } Next, a rule: 1: public interface IRule<T> 2: { 3: Boolean CanSave(T entity, DbContext ctx); 4: Boolean CanUpdate(T entity, DbContext ctx); 5: Boolean CanDelete(T entity, DbContext ctx); 6: String Name 7: { 8: get; 9: } 10: } Let’s analyze what we have, starting with the ruleset: Only has methods for adding a rule, specific to an entity type, and to list all rules of this entity type; By implementing IDisposable, we allow it to be cancelled, by disposing of it when we no longer want its rules to be applied. A rule, on the other hand: Has discrete methods for checking if a given entity can be saved, updated or deleted, which receive as parameters the entity itself and a pointer to the DbContext to which the ruleset was applied; Has a name property for helping us identifying what failed. A ruleset really doesn’t need a public implementation, all we need is its interface. The private (internal) implementation might look like this: 1: sealed class Ruleset : IRuleset 2: { 3: private readonly IDictionary<Type, HashSet<Object>> rules = new Dictionary<Type, HashSet<Object>>(); 4: private ObjectContext octx = null; 5:  6: internal Ruleset(ObjectContext octx) 7: { 8: this.octx = octx; 9: } 10:  11: public void AddRule<T>(IRule<T> rule) 12: { 13: if (this.rules.ContainsKey(typeof(T)) == false) 14: { 15: this.rules[typeof(T)] = new HashSet<Object>(); 16: } 17:  18: this.rules[typeof(T)].Add(rule); 19: } 20:  21: public IEnumerable<IRule<T>> GetRules<T>() 22: { 23: if (this.rules.ContainsKey(typeof(T)) == true) 24: { 25: foreach (IRule<T> rule in this.rules[typeof(T)]) 26: { 27: yield return (rule); 28: } 29: } 30: } 31:  32: public void Dispose() 33: { 34: this.octx.SavingChanges -= RulesExtensions.OnSaving; 35: RulesExtensions.rulesets.Remove(this.octx); 36: this.octx = null; 37:  38: this.rules.Clear(); 39: } 40: } Basically, this implementation: Stores the ObjectContext of the DbContext to which it was created for, this is so that later we can remove the association; Has a collection - a set, actually, which does not allow duplication - of rules indexed by the real Type of an entity (because of proxying, an entity may be of a type that inherits from the class that we declared); Has generic methods for adding and enumerating rules of a given type; Has a Dispose method for cancelling the enforcement of the rules. A (really dumb) rule applied to Product might look like this: 1: class ProductRule : IRule<Product> 2: { 3: #region IRule<Product> Members 4:  5: public String Name 6: { 7: get 8: { 9: return ("Rule 1"); 10: } 11: } 12:  13: public Boolean CanSave(Product entity, DbContext ctx) 14: { 15: return (entity.Price > 10000); 16: } 17:  18: public Boolean CanUpdate(Product entity, DbContext ctx) 19: { 20: return (true); 21: } 22:  23: public Boolean CanDelete(Product entity, DbContext ctx) 24: { 25: return (true); 26: } 27:  28: #endregion 29: } The DbContext is there because we may need to check something else in the database before deciding whether to allow an operation or not. And here’s how to apply this mechanism to any DbContext, without requiring the usage of a subclass, by means of an extension method: 1: public static class RulesExtensions 2: { 3: private static readonly MethodInfo getRulesMethod = typeof(IRuleset).GetMethod("GetRules"); 4: internal static readonly IDictionary<ObjectContext, Tuple<IRuleset, DbContext>> rulesets = new Dictionary<ObjectContext, Tuple<IRuleset, DbContext>>(); 5:  6: private static Type GetRealType(Object entity) 7: { 8: return (entity.GetType().Assembly.IsDynamic == true ? entity.GetType().BaseType : entity.GetType()); 9: } 10:  11: internal static void OnSaving(Object sender, EventArgs e) 12: { 13: ObjectContext octx = sender as ObjectContext; 14: IRuleset ruleset = rulesets[octx].Item1; 15: DbContext ctx = rulesets[octx].Item2; 16:  17: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Added)) 18: { 19: Object entity = entry.Entity; 20: Type realType = GetRealType(entity); 21:  22: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 23: { 24: if (rule.CanSave(entity, ctx) == false) 25: { 26: throw (new Exception(String.Format("Cannot save entity {0} due to rule {1}", entity, rule.Name))); 27: } 28: } 29: } 30:  31: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Deleted)) 32: { 33: Object entity = entry.Entity; 34: Type realType = GetRealType(entity); 35:  36: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 37: { 38: if (rule.CanDelete(entity, ctx) == false) 39: { 40: throw (new Exception(String.Format("Cannot delete entity {0} due to rule {1}", entity, rule.Name))); 41: } 42: } 43: } 44:  45: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Modified)) 46: { 47: Object entity = entry.Entity; 48: Type realType = GetRealType(entity); 49:  50: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 51: { 52: if (rule.CanUpdate(entity, ctx) == false) 53: { 54: throw (new Exception(String.Format("Cannot update entity {0} due to rule {1}", entity, rule.Name))); 55: } 56: } 57: } 58: } 59:  60: public static IRuleset CreateRuleset(this DbContext context) 61: { 62: Tuple<IRuleset, DbContext> ruleset = null; 63: ObjectContext octx = (context as IObjectContextAdapter).ObjectContext; 64:  65: if (rulesets.TryGetValue(octx, out ruleset) == false) 66: { 67: ruleset = rulesets[octx] = new Tuple<IRuleset, DbContext>(new Ruleset(octx), context); 68: 69: octx.SavingChanges += OnSaving; 70: } 71:  72: return (ruleset.Item1); 73: } 74: } It relies on the SavingChanges event of the ObjectContext to intercept the saving operations before they are actually issued. Yes, it uses a bit of dynamic magic! Very handy, by the way! So, let’s put it all together: 1: using (MyContext ctx = new MyContext()) 2: { 3: IRuleset rules = ctx.CreateRuleset(); 4: rules.AddRule(new ProductRule()); 5:  6: ctx.Products.Add(new Product() { Name = "xyz", Price = 50000 }); 7:  8: ctx.SaveChanges(); //an exception is fired here 9:  10: //when we no longer need to apply the rules 11: rules.Dispose(); 12: } Feel free to use it and extend it any way you like, and do give me your feedback! As a final note, this can be easily changed to support plain old Entity Framework (not Code First, that is), if that is what you are using.

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  • Inheritance Mapping Strategies with Entity Framework Code First CTP5: Part 2 – Table per Type (TPT)

    - by mortezam
    In the previous blog post you saw that there are three different approaches to representing an inheritance hierarchy and I explained Table per Hierarchy (TPH) as the default mapping strategy in EF Code First. We argued that the disadvantages of TPH may be too serious for our design since it results in denormalized schemas that can become a major burden in the long run. In today’s blog post we are going to learn about Table per Type (TPT) as another inheritance mapping strategy and we'll see that TPT doesn’t expose us to this problem. Table per Type (TPT)Table per Type is about representing inheritance relationships as relational foreign key associations. Every class/subclass that declares persistent properties—including abstract classes—has its own table. The table for subclasses contains columns only for each noninherited property (each property declared by the subclass itself) along with a primary key that is also a foreign key of the base class table. This approach is shown in the following figure: For example, if an instance of the CreditCard subclass is made persistent, the values of properties declared by the BillingDetail base class are persisted to a new row of the BillingDetails table. Only the values of properties declared by the subclass (i.e. CreditCard) are persisted to a new row of the CreditCards table. The two rows are linked together by their shared primary key value. Later, the subclass instance may be retrieved from the database by joining the subclass table with the base class table. TPT Advantages The primary advantage of this strategy is that the SQL schema is normalized. In addition, schema evolution is straightforward (modifying the base class or adding a new subclass is just a matter of modify/add one table). Integrity constraint definition are also straightforward (note how CardType in CreditCards table is now a non-nullable column). Another much more important advantage is the ability to handle polymorphic associations (a polymorphic association is an association to a base class, hence to all classes in the hierarchy with dynamic resolution of the concrete class at runtime). A polymorphic association to a particular subclass may be represented as a foreign key referencing the table of that particular subclass. Implement TPT in EF Code First We can create a TPT mapping simply by placing Table attribute on the subclasses to specify the mapped table name (Table attribute is a new data annotation and has been added to System.ComponentModel.DataAnnotations namespace in CTP5): public abstract class BillingDetail {     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } } [Table("BankAccounts")] public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } } [Table("CreditCards")] public class CreditCard : BillingDetail {     public int CardType { get; set; }     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } } public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; } } If you prefer fluent API, then you can create a TPT mapping by using ToTable() method: protected override void OnModelCreating(ModelBuilder modelBuilder) {     modelBuilder.Entity<BankAccount>().ToTable("BankAccounts");     modelBuilder.Entity<CreditCard>().ToTable("CreditCards"); } Generated SQL For QueriesLet’s take an example of a simple non-polymorphic query that returns a list of all the BankAccounts: var query = from b in context.BillingDetails.OfType<BankAccount>() select b; Executing this query (by invoking ToList() method) results in the following SQL statements being sent to the database (on the bottom, you can also see the result of executing the generated query in SQL Server Management Studio): Now, let’s take an example of a very simple polymorphic query that requests all the BillingDetails which includes both BankAccount and CreditCard types: projects some properties out of the base class BillingDetail, without querying for anything from any of the subclasses: var query = from b in context.BillingDetails             select new { b.BillingDetailId, b.Number, b.Owner }; -- var query = from b in context.BillingDetails select b; This LINQ query seems even more simple than the previous one but the resulting SQL query is not as simple as you might expect: -- As you can see, EF Code First relies on an INNER JOIN to detect the existence (or absence) of rows in the subclass tables CreditCards and BankAccounts so it can determine the concrete subclass for a particular row of the BillingDetails table. Also the SQL CASE statements that you see in the beginning of the query is just to ensure columns that are irrelevant for a particular row have NULL values in the returning flattened table. (e.g. BankName for a row that represents a CreditCard type) TPT ConsiderationsEven though this mapping strategy is deceptively simple, the experience shows that performance can be unacceptable for complex class hierarchies because queries always require a join across many tables. In addition, this mapping strategy is more difficult to implement by hand— even ad-hoc reporting is more complex. This is an important consideration if you plan to use handwritten SQL in your application (For ad hoc reporting, database views provide a way to offset the complexity of the TPT strategy. A view may be used to transform the table-per-type model into the much simpler table-per-hierarchy model.) SummaryIn this post we learned about Table per Type as the second inheritance mapping in our series. So far, the strategies we’ve discussed require extra consideration with regard to the SQL schema (e.g. in TPT, foreign keys are needed). This situation changes with the Table per Concrete Type (TPC) that we will discuss in the next post. References ADO.NET team blog Java Persistence with Hibernate book a { text-decoration: none; } a:visited { color: Blue; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } p.MsoNormal { margin-top: 0in; margin-right: 0in; margin-bottom: 10.0pt; margin-left: 0in; line-height: 115%; font-size: 11.0pt; font-family: "Calibri" , "sans-serif"; }

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