【发布时间】：2017-04-18 11:20:47
【问题描述】：
我有使用 Code First Entity Framework 6 的 Asp.Net MVC 5 应用程序链接到 MySQL 数据库。
当我第一次创建数据库时，它工作正常。但是当我对模型进行更改时，然后添加迁移。 (Update-Database) 之后显示错误。
这是错误：
PM> Update-Database
System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
at MySql.Data.MySqlClient.MySqlConnectionStringBuilder.<>c.<.cctor>b__2_7(MySqlConnectionStringBuilder msb, MySqlConnectionStringOption sender)
at MySql.Data.MySqlClient.MySqlConnectionStringBuilder.get_Item(String keyword)
at MySql.Data.MySqlClient.MySqlConnectionStringBuilder.GetConnectionString(Boolean includePass)
at MySql.Data.MySqlClient.MySqlConnection.get_ConnectionString()
at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.<GetConnectionString>b__12(DbConnection t, DbConnectionInterceptionContext`1 c)
at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget, TInterceptionContext, TResult](TTarget target, Func`3 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.GetConnectionString(DbConnection connection, DbInterceptionContext interceptionContext)
at System.Data.Entity.Internal.InternalConnection.GetStoreConnectionString(DbConnection connection)
at System.Data.Entity.Internal.InternalConnection.OnConnectionInitialized()
at System.Data.Entity.Internal.EagerInternalConnection..ctor(DbContext context, DbConnection existingConnection, Boolean connectionOwned)
at System.Data.Entity.DbContext..ctor(DbConnection existingConnection, Boolean contextOwnsConnection)
at System.Data.Entity.Migrations.History.HistoryContext..ctor(DbConnection existingConnection, String defaultSchema)
at MySql.Data.Entity.MySqlHistoryContext..ctor(DbConnection existingConnection, String defaultSchema)
at code_first_mysql.Migrations.Configuration.<>c.<.ctor>b__0_0(DbConnection conn, String schema) in C:\Users\User\Documents\Tree\New Backend\code first mysql\Migrations\Configuration.cs:line 16
at System.Data.Entity.Migrations.History.HistoryRepository.CreateContext(DbConnection connection, String schema)
at System.Data.Entity.Migrations.History.HistoryRepository.<GetUpgradeOperations>d__16.MoveNext()
at System.Linq.Enumerable.Any[TSource](IEnumerable`1 source)
at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration)
at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClassc.<Update>b__b()
at System.Data.Entity.Migrations.Infrastructure.MigratorScriptingDecorator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
at System.Data.Entity.Migrations.Infrastructure.MigratorScriptingDecorator.ScriptUpdate(String sourceMigration, String targetMigration)
at System.Data.Entity.Migrations.Design.ToolingFacade.ScriptUpdateRunner.Run()
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
at System.Data.Entity.Migrations.Design.ToolingFacade.ScriptUpdate(String sourceMigration, String targetMigration, Boolean force)
at System.Data.Entity.Migrations.UpdateDatabaseCommand.<>c__DisplayClass2.<.ctor>b__0()
at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
The given key was not present in the dictionary.
这些是我的 MySQL 配置类：
internal sealed class Configuration : DbMigrationsConfiguration<ApplicationDbContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
SetSqlGenerator("MySql.Data.MySqlClient", new MySqlMigrationSqlGenerator());
SetHistoryContextFactory("MySql.Data.MySqlClient", (conn, schema) => new MySqlHistoryContext(conn, schema));
CodeGenerator = new MySqlMigrationCodeGenerator();
}
protected override void Seed(ApplicationDbContext context)
{}
}
public class MySqlConfiguration: DbConfiguration
{
public MySqlConfiguration()
{
SetHistoryContext("MySql.Data.MySqlClient", (conn, schema) => new MySqlHistoryContext(conn, schema));
}
}
public class MySqlHistoryContext : HistoryContext
{
public MySqlHistoryContext(DbConnection existingConnection, string defaultSchema) : base(existingConnection, defaultSchema)
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<HistoryRow>().Property(h => h.MigrationId).HasMaxLength(100).IsRequired();
modelBuilder.Entity<HistoryRow>().Property(h => h.ContextKey).HasMaxLength(200).IsRequired();
}
}
public class MySqlInitializer : IDatabaseInitializer<ApplicationDbContext>
{
public void InitializeDatabase(ApplicationDbContext context)
{
if (!context.Database.Exists())
{
// if database did not exist before - create it
context.Database.Create();
}
else
{
// query to check if MigrationHistory table is present in the database
var migrationHistoryTableExists = ((IObjectContextAdapter)context).ObjectContext.ExecuteStoreQuery<int>(
string.Format(
"SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = '{0}' AND table_name = '__MigrationHistory'", "mydb"));
// if MigrationHistory table is not there (which is the case first time we run) - create it
if (migrationHistoryTableExists.FirstOrDefault() == 0)
{
context.Database.Delete();
context.Database.Create();
}
}
}
}
【问题讨论】：
-
看起来像一个连接字符串问题。您的 dbContext 是否在与启动项目不同的项目中？
-
我只有一个项目，我的 dbContext 也在一个地方。请帮忙..
-
在使用包管理器控制台运行迁移时数据库是否已经创建？如果是这样，您可能错过了与
__MigrationHistory相关的 Code First 迁移的一些步骤。 -
我没听明白，第一个初始化工作正常。但其他人没有。我还添加了迁移历史
标签： mysql asp.net asp.net-mvc entity-framework entity-framework-6