Refined. NET 4.0 (10)-automatically update the database structure (Automatic Migrations) under the Code First of ADO. NET Entity Framework 4.3

[Index page]
[Download source code]

Refined. NET 4.0 (10)-automatically update the database structure (Automatic Migrations) under the Code First of ADO. NET Entity Framework 4.3)

Author: webabcd

Introduction
New Feature of ADO. NET Entity Framework 4.3: automatically update the database structure (Automatic Migrations) under Code First)

Example
Web. config

<? Xml version = "1.0" encoding = "UTF-8"?> <Configuration> <configSections> <section name = "entityFramework" type = "System. data. entity. internal. configFile. entityFrameworkSection, EntityFramework, Version = 4.3.0.0, Culture = neutral, PublicKeyToken = b77a5c561934e089 "/> </configSections> <system. web> <compilation debug = "true" targetFramework = "4.0"/> </system. web> <connectionStrings> <! -- You need to set Persist Security Info to True to save the password information because the Database. setInitializer <MyContext> (new DropCreateDatabaseIfModelChanges <MyContext> ()); when determining whether the Code First and database structures are consistent, you need to connect to the master database --> <add name = "MyConnection" providerName = "System. data. sqlClient "connectionString =" server = .; database = MyDB; uid = sa; pwd = 111111; Persist Security Info = True "/> </connectionStrings> </configuration>

Product. cs

Using System; using System. collections. generic; using System. linq; using System. web; using System. componentModel. dataAnnotations; namespace EF43.UpdateSchema {[Table ("Product")] public class Product {[Key] [DatabaseGenerated (DatabaseGeneratedOption. identity)] public int ProductId {get; set;} [Required] [Column ("ProductName", TypeName = "varchar")] public string Name {get; set ;} /* in order to test the miic Migrations, you can release this annotation, and then Add-Migration will automatically generate the Code related to structure Migration public double Price {get; set ;}*/}}

MyContext. cs

Using System; using System. collections. generic; using System. linq; using System. web; using System. data. entity; namespace EF43.UpdateSchema {// The created Context must inherit from DbContext public class MyContext: DbContext {// specify the database connection as MyConnection public MyContext () in connectionStrings (): base ("MyConnection") {} public DbSet <Product> Products {get; set ;}}}

Demo. aspx. cs

/** Download Entity Framework 4.3 through NuGet ** The following describes how to automatically update the database structure (Automatic Migrations) under Code First: * Note: run the following command on the NuGet Package Manager Console ** after updating the object structure: ** 1. Enable-Migrations * to start the migration function, the Migrations folder is generated under the project root directory, which usually contains two files * 1. configuration. cs-related configuration, such as whether automatic migration (false by default) is required * 2. 201202290715581_InitialCreate.cs-data structure before Migration, the first half is divided into timestamp ** 2, Add-Migration-StartupProjectName EF43 * Add a Migration point in the specified project, this command requires you to enter a Name parameter. The value of this parameter is the migration point Name * assume that the input migration Name is MyFirstTest, a file similar to the following will be generated: 201202290718442_MyTestFirst.cs, it contains two methods: Up () and Down (), upgrade and downgrade of the migration point ** 3. Update-Database-StartupProjectName EF43 (upgrade the Database structure of the specified project to the latest) * Update-Database-TargetMigration: "201202290718442_MyTestFirst", upgrade the current Database structure to this migration point (if there is no parameter-TargetMigration, It is upgraded to the latest) * Update-Database-Script, displays the SQL code * Update-Database-Script-SourceMigration: "aaa"-TargetMigration: "bbb ", displays the SQL code used to upgrade/downgrade the migration point "aaa" to the "bbb" of the migration point. ** Note: if the "System. reflection. targetInvocationException: Exception has been thrown by the target of an invocation "Exception. Check whether the specified project name (-StartupProjectName EF43 in this example) */using System; using System is displayed. collections. generic; using System. linq; using System. web; using System. web. UI; using System. web. UI. webControls; using System. data. entity; namespace EF43.UpdateSchema {public partial class Demo: System. web. UI. page {protected void Page_Load (object sender, EventArgs e) {using (var db = new MyContext () {Random random = new Random (); var product = new Product {Name = "windows" + random. next ()}; db. products. add (product); int recordsAffected = db. saveChanges (); Response. write ("affected database rows:" + recordsAffected. toString ());}}}}

Migrations/Configuration. cs

Namespace EF43.Migrations {using System; using System. data. entity; using System. data. entity. migrations; using System. linq; internal sealed class Configuration: DbMigrationsConfiguration <EF43.UpdateSchema. myContext> {public Configuration () {// the database structure is not automatically migrated by default. There are many other related settings. For details, see DbMigrationsConfiguration <TContext> AutomaticMigrationsEnabled = false ;} protected override void Seed (EF43.UpdateSchema. myContext context) {// This method will be called after migrating to the latest version. // You can use the DbSet <T>. addOrUpdate () helper extension method // to avoid creating duplicate seed data. e. g. /// context. people. addOrUpdate (// p => p. fullName, // new Person {FullName = "Andrew Peters"}, // new Person {FullName = "Brice Lambson "}, // new Person {FullName = "Rowan Miller "}//);//}}}

Migrations/201202290715581_InitialCreate.cs

namespace EF43.Migrations{    using System.Data.Entity.Migrations;        public partial class InitialCreate : DbMigration    {        public override void Up()        {            CreateTable(                "Product",                c => new                    {                        ProductId = c.Int(nullable: false, identity: true),                        ProductName = c.String(nullable: false, unicode: false),                    })                .PrimaryKey(t => t.ProductId);                    }                public override void Down()        {            DropTable("Product");        }    }}

Migrations/201202290718442_MyTestFirst.cs

Namespace EF43.Migrations {using System. data. entity. migrations; public partial class MyTestFirst: DbMigration {public override void Up () {// AddColumn ("Product", "Price", c => c. double (nullable: false); // The automatically generated code is as above. The following is my custom code used to set the default value of the newly added field. // there are many other related settings, for details, see DbMigration AddColumn ("Product", "Price", c => c. double (nullable: false, defaultValue: 10d);} public override void Down () {DropColumn ("Product", "Price ");}}}

 

OK
[Download source code]