Search Results

Search found 906 results on 37 pages for 'ef i blinky'.

Page 2/37 | < Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >

  • 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 !!!

    Read the article

  • 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!!!  

    Read the article

  • Using json as database with EF, how can I link EF and the json file during DbContext initialization?

    - by blacai
    For a personal testing-project I am considering to create a SPA with the following technologies: ASP.NET MVC + EF + WebAPI + AngularJS. The project will make use of small amount of data, so I was thinking I could use just a .json file as storage. But I am not sure about how to proceed with the link between EF and the json file in the initialization of the DbContext. I found a stackoverflow related question: http://stackoverflow.com/questions/13899342/can-we-use-json-as-a-database I know the basics of edit files and store data inside. What I tried is to get the data from the json file in the initilizer method and create the objects one by one. This is more a doubt about how this works if I save/update an object in the dbcontext, do I need to go through all the elements and add/update it manually? Is it better to rewrite the complete file? According to this http://stackoverflow.com/questions/7895335/append-data-to-a-json-file-with-php it is not a good practice to use json/XML for data wich will be manipulated. Anyone has experience with anything similar? Is this a really bad idea and I should use another kind of data-storage?

    Read the article

  • [EF + Oracle]Object Context

    - by JTorrecilla
    Prologue After EF episodes I and II, we are going to see the Object Context. What is Object Context? It is a class which manages the DB connection, and the different Entities of our model. When Visual Studio creates the EF model, like I explain previously, also generates a Class that extends ObjectContext. ObjectContext provides: - DB connection - Add, update and delete functions. - Object Sets of Entities. - State of Pending Changes. This class will give a function, for each Entity, like  Esta clase va a contar con una función, para cada entidad, del tipo “AddTo{ENTITY}({Entity_Type } value)”, which are going to add a Entity to the related ObjectSet. In addition, it has a property, for each Entity, like “ObjectSet<TEntity> Entity”, does will keep the related record set. It will be filled with the CreateObjectSet<TEntity> function of Base class (ObjectContext). What is an ObjectSet? It is a class that allows us to manage the Entity Set from a Type. It inherits from: · ObjectQuery<TEntity> · IObjectSet<TEntity> · IQueryAble<TEntity · IEnumerable<TEntity · IQueryAble · IEnumerable An ObjectSet is a class property that allows query, insert, delete and update records from a determinate Entity. In following chapters we will see how to query Entities. LazyLoadingEnabled A very important property of the Context is “LazyLoadingEnabled”. This Boolean property lets indicate if the data loading is lazy, in other words, the Object will not be created and query until not be needed. Finally In this post we have seen what the VS generated context is, some of the characteristics, and where to see Entity data. In next chapters we will see, CRUD operations, and how to query ObjectSets.

    Read the article

  • 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.

    Read the article

  • Learning resources for working with POCO entities in EF 4.0

    - by boghydan
    Here are some links that can help you start working with POCO entities in EF 4.0: ADO.NET Team blog: - Working with POCO objects: http://blogs.msdn.com/adonet/archive/2009/05/21/poco-in-the-entity-framework-part-1-the-experience.aspx - Proxy objects for POCO entities: http://blogs.msdn.com/adonet/archive/2009/12/22/poco-proxies-part-1.aspx MSDN Library: - Working with POCO  http://msdn.microsoft.com/en-us/library/dd456853.aspx - T4 editor for POCO generator can be downloaded from here: http://visualstudiogallery.msdn.microsoft.com/en-us/60297607-5fd4-4da4-97e1-3715e90c1a23

    Read the article

  • EF 4 Pluralization Update

    - by Ken Cox [MVP]
    I previously wrote about playing with EF 4’s PluralizationService class . Now that OrcsWeb is running ASP.NET 4, you can play with my little pluralization page and its WCF service online. The source code (such as it is!) can be downloaded from the MSDN Code Gallery here: http://code.msdn.microsoft.com/PluralizationService BTW, one annoyance is that the WDSL still includes the default namespace:  namespace="http://tempuri.org/" I swatted a couple of these instances, but if you know...(read more)

    Read the article

  • EF 4 Pluralization Update

    I previously wrote about playing with EF 4s PluralizationService class . Now that OrcsWeb is running ASP.NET 4, you can play with my little pluralization page and its WCF service online. The source code (such as it is!) can be downloaded from the MSDN...(read more)...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • Using multiple diagrams per model in Entity Framework 5.0

    - by nikolaosk
    I have downloaded .Net framework 4.5 and Visual Studio 2012 since it was released to MSDN subscribers on the 15th of August.For people that do not know about that yet please have a look at Jason Zander's excellent blog post .Since then I have been investigating the many new features that have been introduced in this release.In this post I will be looking into theIn order to follow along this post you must have Visual Studio 2012 and .Net Framework 4.5 installed in your machine.Download and install VS 20120 using this link.My machine runs on Windows 8 and Visual Studio 2012 works just fine. I have also installed in my machine SQL Server 2012 developer edition. I have also downloaded and installed AdventureWorksLT2012 database.You can download this database from the codeplex website.   Before I start showcasing the demo I want to say that I strongly believe that Entity Framework is maturing really fast and now at version 5.0 can be used as your data access layer in all your .Net projects.I have posted extensively about Entity Framework in my blog.Please find all the EF related posts here. In this demo I will show you how to split an entity model into multiple diagrams using the new enhanced EF designer. We will not build an application in this demo.Sometimes our model can become too large to edit or view.In earlier versions we could only have one diagram per EDMX file.In EF 5.0 we can split the model into more diagrams.1) Launch VS 2012. Express edition will work fine.2) Create a New Project. From the available templates choose a Web Forms application  3) Add a new item in your project, an ADO.Net Entity Data Model. I have named it AdventureWorksLT.edmx.Then we will create the model from the database and click Next.Create a new connection by specifying the SQL Server instance and the database name and click OK.Then click Next in the wizard.In the next screen of the wizard select all the tables from the database and hit Finish.4) It will take a while for our .edmx diagram to be created. When I select an Entity (e.g Customer) from my diagram and right click on it,a new option appears "Move to new Diagram".Make sure you have the Model Browser window open.Have a look at the picture below 5) When we do that a new diagram is created and our new Entity is moved there.Have a look at the picture below  6) We can also right-click and include the related entities. Have a look at the picture below. 7) When we do that the related entities are copied to the new diagram.Have a look at the picture below  8) Now we can cut (CTRL+X) the entities from Diagram2 and paste them back to Diagram1.9) Finally another great enhancement of the EF 5.0 designer is that you can change colors in the various entities that make up the model.Select the entities you want to change color, then in the Properties window choose the color of your choice. Have a look at the picture below. To recap we have demonstrated how to split your entity model in multiple diagrams which comes handy in EF models that have a large number of entities in them Hope it helps!!!!

    Read the article

  • Tricky situation with EF and Include while projecting (Select / SelectMany)

    - by Vincent Grondin
    Originally posted on: http://geekswithblogs.net/vincentgrondin/archive/2014/06/07/tricky-situation-with-ef-and-include-while-projecting-select.aspxHello, the other day I stumbled on a problem I had a while back with EF and Include method calls and decided this was it and I was going to blog about it…  This would sort of to pin it inside my head and maybe help others too !  So I was using DBContext and wanted to query a DBSet and include some of it’s associations and in the end, do a projection to get a list of Ids…   At first it seems easy…  Query your DBSet, call Include right afterward, then code the rest of your statement with the appropriate where clause and then, do the projection…   Well it wasn’t that easy as my query required I code my where on some entities a few degree further in the association chain and most of these links where “Many”…  I had to do my projection right away with the SelectMany method.  So I did my stuff and tested the query….  no association where loaded…  My Include statement was simply ignored !  Then I remembered this behavior and how to get it to work…  You need to move the Include AFTER your first projection (Select or SelectMany).  So my sequence became:   Query the DBSet, do the projection with SelectMany, Include the associations, code the where clause and do the final projection…. but it wouldn’t compile…   It kept saying that it could not find an “Include” method on an IQueryable… which is perfectly true!  I knew this should work so I went to the definition of the DBset and saw it inherited DBQuery and sure enough the include method was there…  So I had to cast my statement from start until the end of the first projection in a DBQuery then do the Includes and then the rest of my query….   Bottom line is, whenever your Include statement seem to be ignored, then maybe you will need to move them further down in your query and cast your statement in whatever class gives you access to the Include…   Happy coding all !

    Read the article

  • [EF + Oracle] Inserting Data (1/2)

    - by JTorrecilla
    Prologue Following EF series (I ,II y III) in this chapter we will see how to create DB record from EF. Inserting Data Like we indicated in the 2º post: “One Entity matches with a DB record, and one property match with a Table Column”. To start, we need to create an object from one of the Entities: 1: EMPLEADOS empleado = new EMPLEADOS(); Also like, I told previously, Exists the possibility to use the Static Function defined by VS for each Entity: Once we have created the object, we can Access to it properties to fill like a common class:   1: empleado.NOMBRE = "Javier Torrecilla";   After finish of fill our Entity properties, it must be needed to add the object to the appropriate ObjectSet in the ObjectContext: 1: enti.EMPLEADOS.AddObject(empleado); or 1: enti.AddToEMPLEADOS(empleado); Both methods will do the same action, create an insert statement. Have we finished? No. Any Entity has a property called “EntityState”. This prop is an Enum from “EntityState”, which has the following: Detached: the Entity is created, but not added to the Context. Unchanged: There is no pending changes in the Entity. Added: The entity is added to the ObjectSet, but it is not yet sent to the DB. Deleted: The object is deleted form the ObjectSet, but not yet from the DB. Modified: There is Pending Changes to confirm. Let’s see, the several values of the property during the Creation steps: 1. While the Object is created and we are filling the props: EntityState.Detached; 2. After adding to the ObjectSet: EntityState.Added. This not indicated that the record is in the DB 3. Saving the Data: To sabe the data in the DB, we are going to call “SaveChanges” method of the Object Context. After invoke it, the property will be EntityState.Unchanged.   What does SaveChanges Method? This function will synchronize and send all pending changes to DB. It will add, modify or delete all Entities, whose EntityState property, is setted to Added, Deleted or Modified. After finishing, all added or modified entities will be change the State to “Unchanged”, and deleted Entities must take the “Detached” state.

    Read the article

  • [EF + Oracle] Entities

    - by JTorrecilla
    Prologue Following with the Serie I started yesterday about Entity Framework with Oracle, Today I am going to start talking about Entities. What is an Entity? A Entity is an object of the EF model corresponding to a record in a DB table. For example, let’s see, in Image 1 we can see one Entity from our model, and in the second one we can see the mapping done with the DB. (Image 1) (Image 2) More in depth a Entity is a Class inherited from the abstract class “EntityObject”, contained by the “System.Data.Objects.DataClasses” namespace. At the same time, this class inherits from the following Class and interfaces: StructuralObject: It is an Abstract class that inherits from INotifyPropertyChanging and INotifyPropertyChanged interfaces, and it exposes the events that manage the Changes of the class, and the functions related to check the data types of the Properties from our Entity.  IEntityWithKey: Interface which exposes the Key of the entity. IEntityWithChangeTracker: Interface which lets indicate the state of the entity (Detached, Modified, Added…) IEntityWithRelationships: Interface which indicates the relations about the entity. Which is the Content of a Entity? A Entity is composed by: Properties, Navigation Properties and Methods. What is a Property? A Entity Property is an object that represents a column from the mapped table from DB. It has a data type equivalent in .Net Framework to the DB Type. When we create the EF model, VS, internally, create the code for each Entity selected in the Tables step, such all methods that we will see in next steps. For each property, VS creates a structure similar to: · Private variable with the mapped Data type. · Function with a name like On{Property_Name}Changing({dataType} value): It manages the event which happens when we try to change the value. · Function with a name like On{Property_Name}Change: It manages the event raised when the property has changed successfully. · Property with Get and Set methods: The Set Method manages the private variable and do the following steps: Raise Changing event. Report the Entity is Changing. Set the prívate variable. For it, Use the SetValidValue function of the StructuralObject. There is a function for each datatype, and the functions takes 2 params: the value, and if the prop allow nulls. Invoke that the entity has been successfully changed. Invoke the Changed event of the Prop. ReportPropertyChanging and ReportPropertyChanged events, let, respectively, indicate that there is pending changes in the Entity, and the changes have success correctly. While the ReportPropertyChanged is raised, the Track State of the Entity will be changed. What is a Navigation Property? Navigation Properties are a kind of property of the type: EntityCollection<TEntity>, where TEntity is an Entity type from the model related with the current one, it is said, is a set of record from a related table in the DB. The EntityCollection class inherits from: · RelatedEnd: There is an abstract class that give the functions needed to obtein the related objects. · ICollection<TEntity> · IEnumerable<TEntity> · IEnumerable · IListSource For the previous interfaces, I wish recommend the following post from Jose Miguel Torres. Navigation properties allow us, to get and query easily objects related with the Entity. Methods? There is only one method in the Entity object. “Create{Entity}”, that allow us to create an object of the Entity by sending the parameters needed to create it. Finally After this chapter, we know what is an Entity, how is related to the DB and the relation to other Entities. In following chapters, we will se CRUD operations(Create, Read, Update, Delete).

    Read the article

  • Why LLBLGen Pro v3.0 is better than the regular designer for EF v4.0

    As a comment to my blogpost about the 12 minute long video of LLBLGen Pro with Entity Framework v4.0, Burton Roberts asks: Could you list the advantages of using llblgen pro 3 with Entity Framework versus using EF alone? Of course! Now, I know these posts are often classified as 'marketing' but so be it. Why is the LLBLGen Pro v3.0 designer better for Entity Framework v4.0 than the regular Entity Framework designer? Below I'll give an (incomplete) list of features you have at your disposal...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • Building a Repository Pattern against an EF 5 EDMX Model - Part 1

    - by Juan
    I am part of a year long plus project that is re-writing an existing application for a client.  We have decided to develop the project using Visual Studio 2012 and .NET 4.5.  The project will be using a number of technologies and patterns to include Entity Framework 5, WCF Services, and WPF for the client UI.This is my attempt at documenting some of the successes and failures that I will be coming across in the development of the application.In building the data access layer we have to access a database that has already been designed by a dedicated dba. The dba insists on using Stored Procedures which has made the use of EF a little more difficult.  He will not allow direct table access but we did manage to get him to allow us to use Views.  Since EF 5 does not have good support to do Code First with Stored Procedures, my option was to create a model (EDMX) against the existing database views.   I then had to go select each entity and map the Insert/Update/Delete functions to their respective stored procedure. The next step after I had completed mapping the stored procedures to the entities in the EDMX model was to figure out how to build a generic repository that would work well with Entity Framework 5.  After reading the blog posts below, I adopted much of their code with some changes to allow for the use of Ninject for dependency injection.http://www.tcscblog.com/2012/06/22/entity-framework-generic-repository/ http://www.tugberkugurlu.com/archive/generic-repository-pattern-entity-framework-asp-net-mvc-and-unit-testing-triangle IRepository.cs public interface IRepository : IDisposable where T : class { void Add(T entity); void Update(T entity, int id); T GetById(object key); IQueryable Query(Expression> predicate); IQueryable GetAll(); int SaveChanges(); int SaveChanges(bool validateEntities); } GenericRepository.cs public abstract class GenericRepository : IRepository where T : class { public abstract void Add(T entity); public abstract void Update(T entity, int id); public abstract T GetById(object key); public abstract IQueryable Query(Expression> predicate); public abstract IQueryable GetAll(); public int SaveChanges() { return SaveChanges(true); } public abstract int SaveChanges(bool validateEntities); public abstract void Dispose(); } One of the issues I ran into was trying to do an update. I kept receiving errors so I posted a question on Stack Overflow http://stackoverflow.com/questions/12585664/an-object-with-the-same-key-already-exists-in-the-objectstatemanager-the-object and came up with the following hack. If someone has a better way, please let me know. DbContextRepository.cs public class DbContextRepository : GenericRepository where T : class { protected DbContext Context; protected DbSet DbSet; public DbContextRepository(DbContext context) { if (context == null) throw new ArgumentException("context"); Context = context; DbSet = Context.Set(); } public override void Add(T entity) { if (entity == null) throw new ArgumentException("Cannot add a null entity."); DbSet.Add(entity); } public override void Update(T entity, int id) { if (entity == null) throw new ArgumentException("Cannot update a null entity."); var entry = Context.Entry(entity); if (entry.State == EntityState.Detached) { var attachedEntity = DbSet.Find(id); // Need to have access to key if (attachedEntity != null) { var attachedEntry = Context.Entry(attachedEntity); attachedEntry.CurrentValues.SetValues(entity); } else { entry.State = EntityState.Modified; // This should attach entity } } } public override T GetById(object key) { return DbSet.Find(key); } public override IQueryable Query(Expression> predicate) { return DbSet.Where(predicate); } public override IQueryable GetAll() { return Context.Set(); } public override int SaveChanges(bool validateEntities) { Context.Configuration.ValidateOnSaveEnabled = validateEntities; return Context.SaveChanges(); } #region IDisposable implementation public override void Dispose() { if (Context != null) { Context.Dispose(); GC.SuppressFinalize(this); } } #endregion IDisposable implementation } At this point I am able to start creating individual repositories that are needed and add a Unit of Work.  Stay tuned for the next installment in my path to creating a Repository Pattern against EF5.

    Read the article

  • Today is last chance for EF Profiler 30% discount

    Ayende has reminded us that Entity Framework Profiler’s Beta period ends tomorrow when it goes RTM. But that means the 30% discount also ends. It will go from $220US to $315US tomorrow. I spend a lot of time looking at what’s going on in my database when using EF and the views that EFProf provide are indispensible. It’s organized by context instance and provides links back to the .NET code that executed each command. I sure wish I had stock in this tool! ...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • DAL Layer : EF 4.0 or Normal Data access layer with Stored Procedure

    - by Harryboy
    Hello Experts, Application : I am working on one mid-large size application which will be used as a product, we need to decide on our DAL layer. Application UI is in Silverlight and DAL layer is going to be behind service layer. We are also moving ahead with domain model, so our DB tables and domain classes are not having same structure. So patterns like Data Mapper and Repository will definitely come into picture. I need to design DAL Layer considering below mentioned factors in priority manner Speed of Development with above average performance Maintenance Future support and stability of the technology Performance Limitation : 1) As we need to strictly go ahead with microsoft, we can not use NHibernate or any other ORM except EF 4.0 2) We can use any code generation tool (Should be Open source or very cheap) but it should only generate code in .Net, so there would not be any licensing issue on per copy basis. Questions I read so many articles about EF 4.0, on outset it looks like that it is still lacking in features from NHibernate but it is considerably better then EF 1.0 So, Do you people feel that we should go ahead with EF 4.0 or we should stick to ADO .Net and use any code geneartion tool like code smith or any other you feel best Also i need to answer questions like what time it will take to port application from EF 4.0 to ADO .Net if in future we stuck up with EF 4.0 for some features or we are having serious performance issue. In reverse case if we go ahead and choose ADO .Net then what time it will take to swith to EF 4.0 Lastly..as i was going through the article i found the code only approach (with POCO classes) seems to be best suited for our requirement as switching is really easy from one technology to other. Please share your thoughts on the same and please guide on the above questions

    Read the article

  • EF 4’s PluralizationService Class: A Singularly Impossible Plurality

    - by Ken Cox [MVP]
    Entity Framework’s new 4.0 designer does its best to generate correct plural and singular forms of object names. This magic is done through the PluralizationService Class found in the System.Data.Entity.Design.PluralizationServices namespace and in the System.Data.Entity.Design.dll assembly. [Before you ask… Yes, I’ll post my example page, the service, and the project source code as soon as my ISP makes ASP.NET 4 RTM available. Stay tuned.] Anyone who speaks English is brutally aware of the ridiculous...(read more)

    Read the article

  • Usage of repository between EF model and code consumer

    - by jim
    I have binary data in my database that I'll have to convert to bitmap at some point. I was thinking whether or not it's appropriate to use a repository and do it there. My consumer, which is a presentation layer, will use this repository. For example: // This is a class I created for modeling the item as is. public class RealItem { public string Name { get; set; } public Bitmap Image { get; set; } } public abstract class BaseRepository { //using Unity (http://unity.codeplex.com) to inject the dependancy of entity context. [Dependency] public Context { get; set; } } public calss ItemRepository : BaseRepository { public List<Items> Select() { IEnumerable<Items> items = from item in Context.Items select item; List<RealItem> lst = new List<RealItem>(); foreach(itm in items) { MemoryStream stream = new MemoryStream(itm.Image); Bitmap image = (Bitmap)Image.FromStream(stream); RealItem ritem = new RealItem{ Name=item.Name, Image=image }; lst.Add(ritem); } return lst; } } Is this a correct way to use the repository pattern? I'm learning this pattern and I've seen a lot of examples online that are using a repository but when I looked at their source code... for example: public IQueryable<object> Select { return from q in base.Context select q; } as you can see no behavior is added to the system by their approach, so I was confused that maybe repository is something else and I got it all wrong. At the end there should be extra benifits of using them right?

    Read the article

  • How do you handle EF Data Contexts combined with asp.net custom membership/role providers

    - by KallDrexx
    I can't seem to get my head around how to implement a custom membership provider with Entity Framework data contexts into my asp.net MVC application. I understand how to create a custom membership/role provider by itself (using this as a reference). Here's my current setup: As of now I have a repository factory interface that allows different repository factories to be created (right now I only have a factory for EF repositories and and in memory repositories). The repository factory looks like this: public class EFRepositoryFactory : IRepositoryFactory { private EntitiesContainer _entitiesContext; /// <summary> /// Constructor that generates the necessary object contexts /// </summary> public EFRepositoryFactory() { _entitiesContext = new EntitiesContainer(); } /// <summary> /// Generates a new entity framework repository for the specified entity type /// </summary> /// <typeparam name="T">Type of entity to generate a repository for </typeparam> /// <returns>Returns an EFRepository</returns> public IRepository<T> GenerateRepository<T>() where T : class { return new EFRepository<T>(_entitiesContext); } } Controllers are passed an EF repository factory via castle Windsor. The controller then creates all the service/business layer objects it requires and passes in the repository factory into it. This means that all service objects are using the same EF data contexts and I do not have to worry about objects being used in more than one data context (which of course is not allowed and causes an exception). As of right now I am trying to decide how to generate my user and authorization service layers, and have run against a design roadblock. The User/Authization service will be a central class that handles the logic for logging in, changing user details, managing roles and determining what users have access to what. The problem is, using the current methodology the asp.net mvc controllers will initialize it's own EF repository factory via Windsor and the asp.net membership/role provider will have to initialize it's own EF repository factory. This means that each part of the site will then have it's own data context. This seems to mean that if asp.net authenticates a user, that user's object will be in the membership provider's data context and thus if I try to retrieve that user object in the service layer (say to change the user's name) I will get a duplication exception. I thought of making the repository factory class a singleton, but I don't see a way for that to work with castle Windsor. How do other people handle asp.net custom providers in a MVC (or any n-tier) architecture without having object duplication issues?

    Read the article

  • How to pass a Lambda Expression as method parameter with EF

    - by Registered User
    How do I pass an EF expression as a method argument? To illustrate my question I have created a pseudo code example: The first example is my method today. The example utilizes EF and a Fancy Retry Logic. What I need to do is to encapsulate the Fancy Retry Logic so that it becomes more generic and does not duplicate. In the second example is how I want it to be, with a helper method that accepts the EF expression as an argument. This would be a trivial thing to do with SQL, but I want to do it with EF so that I can benefit from the strongly typed objects. First Example: public static User GetUser(String userEmail) { using (MyEntities dataModel = new MyEntities ()) { var query = FancyRetryLogic(() => { (dataModel.Users.FirstOrDefault<User>(x => x.UserEmail == userEmail))); }); return query; } } Second Example: T RetryHelper<T>(Expression<Func<T, TValue>> expression) { using (MyEntities dataModel = new (MyEntities ()) { var query = FancyRetryLogic(() => { return dataModel.expression }); } } public User GetUser(String userEmail) { return RetryHelper<User>(<User>.FirstOrDefault<User>(x => x.UserEmail == userEmail)) }

    Read the article

  • solution on SP and EF & Ria Service

    - by KentZhou
    As EF 4.0 released, more support to SQL server Stored procedure. Complex Type can be generated automatically for result dataset of SP. But complex type not support by Ria Service. When I try to use ria service combined with EF 4.0, I want to get dataset by SP. This result is not mapped to any entity/table. Some sulutions suggested by community are: 1. Create view to map sp result. (but for EF, if there is no ID or primary, can't be map to any entity) 2. Create Entity to map sp result.(for this, you even need to map SP for CRUD even though I don't need CUD on this sp result) Also above solution can't be automated. As Database objects maybe changed with the time, auto update edm will lost above solution. So what's the solution? I want to put data operation back to DB as possible, so that many changes can be done in DB and no need to rebuild .net assemblies(this cause redeploy).

    Read the article

  • EF problem with entity re-ordering and uniqueness constraint

    - by wpfwannabe
    I am using Entity Framework and I've come to an interesting stumbling block. Let's say there is a db table "Item" with "sequence" column of type int (and others of course). Column "sequence" must be unique and it is used for (re)ordering of items. EF maps this table to "Item" class with "sequence" int property. Now let's say I want to swap position of two items by mutually exchanging each other's sequence number. Upon calling SaveChanges() EF throws an exception complaining about "sequence" uniqueness. It probably generates two UPDATEs and the first one probably fails. I assume that plain SQL solution to this issue is using a third UPDATE to introduce a unique sequence value in the process but I am stuck with EF. Any thoughts?

    Read the article

  • Bound a treeview control to user-defined complex type using EF 4

    - by GIbboK
    Hi, I use Asp.net, SQL 2008 and EF 4. I need display hierarchy data in a treeview control, Data is stored in a DB that use HierarchyId. Unfortunately, EF4 doesn't support HierarchyId. So in this case, I thought to have a stored procedure that deals with my hierarchy and return a result set back to EF that EF4 can turn into a collection of user-defined complex type that can then be bound directly to the treeview control. I imported a SPROC in EF 4 using Import Function and now I have a Complex DataType called: CategoryHierarchy_Result An image of my Model: Here some data from the Complex Type (in a GridView for example GridView1.DataSource = context.CategoryHierarchy(1);): My questions is: How to display my data from my Complex Type in a TreeView Control, showing a Tree structure that respect CategoryNodeString? I am a beginner an I never use TreeView before, any help or resource would be appreciated! Thanks!. Here some useful resource: http://www.robbagby.com/entity-framework/entity-framework-modeling-action-stored-procedures/

    Read the article

  • Custom OData operation / customize EF model to hide join table in many-to-many relationship

    - by AC
    I've got a data model that has two tables with a join table for a many to many relationship & creating an OData service to expose the data for CRUD ops in a Silverlight app. What I'd like to do is abstract the join table from the service. I'm not sure if the best way to do this would be in the model (using EF in .NET3.5SP1) or if I should do it with a custom service operation. If I do it in the EF model (not sure how I'd do this), then the OOTB WCF Data Service stuff would make it easy to say [..]/Courses(1)/Modules ... otherwise I'd have to create a custom operation to do this. Is it possible to do this in the EF model and if so, how does that work?

    Read the article

  • Using EF 4 on .NET 3.5 SP1

    - by KiD0M4N
    Hi guys, I was using the latest EF 4 bits in Visual Studio 2010 RC and have fallen in love with it. However, I have to develop a small web application using .NET 3.5 SP1 (VS 2008) for work... I was wondering if it was possible to somehow utilize EF 4 in .NET 3.5 SP1/VS 2008. Regards, Karan Misra

    Read the article

< Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >