Articles

Code First

EF Code First...What is Entity Framework Code First?...When you start learning Entity Framework, you will often see the term ...Entity Framework Code First.... Code first is one of the three approaches to create an entity model....Answer...In Entity Framework, code first was introduced in Entity Framework 4.1. Code First modeling workflow targets a database that doesn't exist, and Code First will create it....Code-First APIs will create the database on the fly based on your entity classes and co...

Code First vs Database First

Code First vs Database First...Code First vs Database First...When you start learning Entity Framework, you will often see the the following two terms;...Code Fist...Database First...What is the difference between ...Code First... and ...Database First... in Entity Framework?...StackOverflow Related Questions...What is the difference between 'Database First' and 'Code First to Existing Database' in Entity Framework...Code-first vs Model/Database-first [closed]...Answer...Code First Approach...Co...

Column

Column...In EF 6, the default convention creates a creates a column name similar to the property name in an entity class....It is also the same as ...Table... attribute, but ...Table... attribute overrides the table behavior while ...Column... attribute overrides the column behavior....It will create a column in a database with a specified name in the ...Column... attribute for a given property....The following example maps the ...BookTitle... property in the Book entity to a database column nam...

Complex Type

ComplexType...The Complex types are non-scalar properties of entity types that enable scalar properties to be organized within entities....ComplexType... doesn't have keys and therefore cannot exist independently....It can only exist as properties of entity types or other complex types....It cannot participate in associations and cannot contain navigation properties....Complex type properties cannot be null....Scalar properties of complex objects can be null....In the following example, we have ...

Concurrency Check

ConcurrencyCheck...The ...ConcurrencyCheck... attribute allows you to configure one or more properties to be used for concurrency checking in the database when a user edits or deletes an entity....You can use ...ConcurrencyCheck... attribute when you want to use existing columns for concurrency check....It is used to specify that a property should be included in a ...WHERE... clause in an ...UPDATE... or ...DELETE... statement....In the following example, the ...ConcurrencyCheck... attribute is ...

Data Annotations

Data Annotations...In .NET Framework, data annotation add extra meaning to the data by adding attribute tags. It is used to configure the classes which will highlight the most commonly needed configurations....Data Annotations attributes are .NET attributes which can be applied to an entity class or properties to override default CodeFirst conventions in EF6 and EF Core....The advantage of using Data Annotation feature is that by applying Data Attributes, we can manage the data definition in a s...

Database Generated

DatabaseGenerated...The ...DatabaseGenerated... attribute added to the properties whose value is automatically computed/updated by the Database. It specifies how the database generates values for the property. There are three possible values:...Identity...: Specifies that the column is an identity column, which is typically used for integer primary keys....Computed...: Specifies that the database generates the value for the column....None...: Specifies that the values are not generated by the da...

EF6 - Code First

Entity Framework - Code First...In the ...previous post..., I talked about how to work with Entity Framework using the Designer, a class model created from an ...EDMX... file. This model works perfectly in different types of projects, but the big drawback is having an ...EDMX... file for each database in your project....So let's now take a different approach, but not that different from the previous article. Our need is still to maintain the isolation of the database and to work only with object...

EF6 - Code First from Database!

EntityFramework - Reading your database with Visual Studio 2013 Update 2...Some time ago, I made a post talking about how to ...take advantage of your existing database with EntityFramework Power Tools..., but the Power Tools model does not allow you to choose the tables or views you want to read, and sometimes this is very useful....With the release of Visual Studio 2013 Update 2, and also EntityFramework 6.1, a new option was added in the data sources. It now allows making ...reverse engineeri...

EF6 - Creating Index

Creating indexes in Entity Framework Code First...As of EntityFramework version 6.1, it is possible to create ...index... in the database, specifying this directly in the classes in the source code. This creation of the indexes is carried out through the ...Index... attribute directly to the class property. But beware: this is only possible using EntityFramework's Migrations feature....To demonstrate this feature, let's create a Console project in Visual Studio and add the Entity Framework Code ...

EF6 - Stored Procedure

EF Code First - Accessing Stored Procedures...I'll start this post by stating that Entity Framework Code First does not have native support for Stored Procedures, yet!...But if it is not supported natively, then how is it possible to access them? Through the context's ...SqlQuery()... method. But there is a drawback: access is linked to the database provider! Each database provider has a specific way of calling and treat stored procedure parameters....In our example, we will demonstrate how to a...

Fluent API

Fluent API...When working with Entity Framework Code First the default behavior is to map your POCO classes to tables using a set of conventions baked into EF....Fluent API specify the model configuration that you can with data annotations as well as some additional functionality that can not be possible with data annotations....We can configure many different things by using it because it provides more configuration options than data annotation attributes....Data annotations and the fluent API ...

Foreign Key

ForeignKey...The ...ForeignKey... attribute is used to specify which property is the foreign key in a relationship. It is used to express the relationship between two tables....The default code first convention for ForeignKey relationship expects foreign key property name match with the primary key property....If your code is not using the default code first conventions, then you can use ...ForeignKey... attribute, so that code first can identify that it contains the foreign key....In the follow...

Inverse Property

InverseProperty...The ...InverseProperty... attribute is used to denote the inverse navigation property of a relationship when the same type takes part in multiple relationships....It is used when you need to indicate that navigation property in one class is related to the same foreign key as another navigation property in another class....For example, in the ...Book... class, you may want to keep track of who wrote a book as well as who edited it....In the following example, we have added two n...

Key

Key...The ...Key... attribute can be applied to a property to make it a key property in an entity class and the corresponding column to a primary key column in the database....The default Code First convention look for a property named ..."Id"..., or a combination of ..."class name"... and ..."Id"..., such as ...BookId.......This property will map to a primary key column in the database....public class Book { public int BookId { get; set; } public string Title { get; set; } } public cla...

Max Length

MaxLength...The ...MaxLength... attributes allow you to specify additional property validations. It is applied to a property to specify a maximum number of characters or bytes for the column that the property should map to....The following example specifies that the ...Title... column in the Books table have a maximum length of 12 characters....public class Book { public int BookId { get; set; } [MaxLength(12)] public string Title { get; set; } } ...Try it...If you set a value of Tit...

Migration

Migration...The Migrations feature enables you to change the data model and deploy your changes to production by updating the database schema without having to drop and re-create the database. It is the recommended way to evolve your application's database schema if you are using the Code First workflow....Migrations provide a set of tools that allow:...Create an initial database that works with your EF model...Generating migrations to keep track of changes you make to your EF model...Keep your ...

Min Length

MinLength...The ...MinLength... attributes allow you to specify additional property validations. It is applied to a property to specify a minimum number of characters or bytes for the column that the property should map to....The following example specifies that the ...Title... column in the Books table must have a minimum length of 5 characters....public class Book { public int BookId { get; set; } [MinLength(5)] public string Title { get; set; } } ...Try it...If you set a value of ...

Not Mapped

NotMapped...The ...NotMapped... attribute is used to specify that an entity or property is not to be mapped to a table or column in the database....In EF, the default Code First conventions create a column for every property that is of a supported data type and which includes getters and setters....The ...NotMapped... attribute overrides this default convention, and the entity or property will not be mapped to a table or column in the database....The following example will not be map the ...Audi...

Required

Required...The ...Required... attribute can be applied to a property to make it a required property in an entity class....EF will create a ...NOT NULL... column in a database table for a property on which the ...Required... attribute is applied....If you save an entity without assigning a value to the ...Required... property, then EF 6 will throw the ...System.Data.Entity.Validation.DbEntityValidationException... exception....public class Book { public int BookId { get; set; } [Required]...

String Length

StringLength...The ...StringLength... attributes allow you to specify additional property validations like ...MaxLength.......It is applied to a property to specify a maximum number of characters or bytes for the column that the property should map to....The only difference is that ...StringLength... attribute can only be applied to a string type property of Domain classes....The following example specifies that the ...Title... column in the Books table have a maximum length of 12 characters....

Table

Table...In EF 6, the default convention creates a table name matching with ...<DbSet<TEntity> property name>... + 's' or 'es' in a context class....The ...Table... attribute overrides this default convention....It is applied to an entity to specify the name of the database table that the entity should map to....The following example specifies that the ...Book... entity should map to a database table named ...BooksInfo.......[Table("BooksInfo")] public class Book { public int BookId { get; se...

Timestamp

Timestamp...The ...TimeStamp... attribute is used to creates a column with timestamp data type in the SQL Server database....EF Code first will treat ...Timestamp... properties the same as ConcurrencyCheck properties....It can only be applied once in an entity class to a byte array type property....It will also ensure that the database field that code first generates is non-nullable....Entity Framework API automatically uses this ...Timestamp... column in concurrency check on the ...UPDATE... st...