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.

I have Asp.Net MVC 5 application using Code First Entity Framework 6 linked to MySQL database.

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.

When I created the database first time, it works fine. But when I make a change to the model then add migration. An error shows after (Update-Database).

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:UsersUserDocumentsTreeNew Backendcode first mysqlMigrationsConfiguration.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:

These are my MySQL Configuration Classes:

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();
            }
        }
    }
}

推荐答案

从错误的第一行可以看出，

As you see from the first lines of the error,

MySql.Data.MySqlClient.MySqlConnectionStringBuilder.<>c.<.cctor>b__2_7(MySqlConnectionStringBuildermsb，MySqlConnectionStringOption 发件人)在 MySql.Data.MySqlClient.MySqlConnectionStringBuilder.get_Item(字符串关键字)

MySql.Data.MySqlClient.MySqlConnectionStringBuilder.<>c.<.cctor>b__2_7(MySqlConnectionStringBuilder msb, MySqlConnectionStringOption sender) at MySql.Data.MySqlClient.MySqlConnectionStringBuilder.get_Item(String keyword)

错误与 ConnectionString 有关.问题是 ConnectionString 包含无法读取的键.

the error has to do with the ConnectionString. The problem is the ConnectionString contains keys that can't be read.

尝试清理 ConnectionString 使其只有

1. 服务器
2. 用户 ID
3. 密码
4. 数据库

在我的例子中，ConnectionString 有一个额外的密钥integrated security.当这被删除 Update-Database 开始工作正常.但是，根据您的情况，这可能是也可能不是导致错误的关键.

In my case, the ConnectionString had an extra key integrated security. When this was removed Update-Database started working fine. Depending on your case however, this might and might not be the key that caused the error.

所以我再次提出并保证解决方案，检查 ConnectionString 并简化它，使其仅包含上面提到的 4 个键.

So again my proposed and guaranteed solution, go through ConnectionString and simplify it so that it contains only the 4 keys mentioned above.

这篇关于EF6 与 MySQL.字典中不存在给定的键的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！