SQLite.CodeFirst - 创建模型时无法使用上下文

Question

我正在使用SQLite数据库的WPF应用程序。尝试用SQLite.CodeFirst的代码优先方法设计数据库。

错误如下：{“创建模型时无法使用上下文。如果在OnModelCreating方法内部使用上下文，或者多个线程同时访问同一上下文实例，则可能会抛出此异常。的DbContext和相关类中的实例成员不能保证线程安全“}使用

进出口代码：

1. 的DbContext：

   class GestDbContext : DbContext 
   { 
       override protected void OnModelCreating(DbModelBuilder modelBuilder) 
       { 
        var model = modelBuilder.Build(Database.Connection); 
        IDatabaseCreator sqliteDatabaseCreator = new SqliteDatabaseCreator(); 
        sqliteDatabaseCreator.Create(Database, model); 
       } 
   
       public DbSet<GestUser> GestUsers { get; set; } 
       public DbSet<Gesture> Gestures { get; set; } 
       public DbSet<UserSettings> UserSettings { get; set; } 
   
   } 
   

2. MainWindowViewModel - 只是初始化数据库

   #region Constructor 
   public MainWindowViewModel() 
   { 
       using (var context = new GestDbContext()) 
       { 
        var entity = context.Gestures.Any(); 
       } 
   } 
   #endregion 
   

3. 的App.config

   <entityFramework> <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework"> <parameters> <parameter value="mssqllocaldb" /> </parameters> </defaultConnectionFactory> <providers> <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" /> <provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" /> <provider invariantName="System.Data.SQLite" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" /> </providers> </entityFramework> <system.data> <DbProviderFactories> <remove invariant="System.Data.SQLite.EF6" /> <add name="SQLite Data Provider (Entity Framework 6)" invariant="System.Data.SQLite.EF6" description=".NET Framework Data Provider for SQLite (Entity Framework 6)" type="System.Data.SQLite.EF6.SQLiteProviderFactory, System.Data.SQLite.EF6" /> </DbProviderFactories> </system.data> <connectionStrings> <add name="connection" connectionString="Data Source=.\GestDB" providerName="System.Data.SqlLite"/> </connectionStrings>

Answer 1

我在变量实例保存从OnModelCreating模型构建器

private DbModelBuilder _modelBuilder; 
override protected void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
    _modelBuilder = modelBuilder; 
} 

然后把它用在一个公共方法：

public void Init() 
{ 
    var model = _modelBuilder.Build(Database.Connection); 
    IDatabaseCreator sqliteDatabaseCreator = new SqliteDatabaseCreator(); 
    sqliteDatabaseCreator.Create(Database, model); 
} 

并执行它一次（我需要创建结构一次）

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