Question

我想在Unity中使用通过实体框架的SQLite数据库。但是在运行时会发生错误：

NotSupportedException：无法确定类型'System.Data.SQLite.SQLiteConnection'的连接的DbProviderFactory类型。确保已在应用程序配置中安装或注册了ADO.NET提供程序。

这是我的Entity Framework配置：

class SqliteDbConfiguration : DbConfiguration
{
    public SqliteDbConfiguration()
    {
        string assemblyNameEF6 = typeof(SQLiteProviderFactory).Assembly.GetName().Name;

        RegisterDbProviderFactories<SQLiteProviderFactory>("SQLite Data Provider (Entity Framework 6)", ".NET Framework Data Provider for SQLite (Entity Framework 6)");
        RegisterDbProviderFactories<SQLiteFactory>("SQLite Data Provider", ".NET Framework Data Provider for SQLite");

        SetProviderFactory(assemblyNameEF6, SQLiteFactory.Instance);
        SetProviderFactory(assemblyNameEF6, SQLiteProviderFactory.Instance);
        SetProviderFactory("System.Data.SQLite", SQLiteFactory.Instance);

        DbProviderServices provider = (DbProviderServices)SQLiteProviderFactory.Instance.GetService(typeof(DbProviderServices));

        SetProviderServices(assemblyNameEF6, provider);
        SetProviderServices("System.Data.SQLite", provider);
        SetProviderServices("System.Data.SqlClient", System.Data.Entity.SqlServer.SqlProviderServices.Instance);

        SetDefaultConnectionFactory(new System.Data.Entity.Infrastructure.LocalDbConnectionFactory("mssqllocaldb"));

        AddDependencyResolver(new SingletonDependencyResolver<DbProviderFactory>(SQLiteProviderFactory.Instance));
    }

    static void RegisterDbProviderFactories<T>(string name, string description)
    {
        string assemblyName = typeof(T).Assembly.GetName().Name;
        var dataSet = ConfigurationManager.GetSection("system.data") as DataSet;
        if (dataSet != null)
        {
            var dbProviderFactoriesDataTable = dataSet.Tables.OfType<DataTable>()
                .First(x => x.TableName == typeof(DbProviderFactories).Name);

            var dataRow = dbProviderFactoriesDataTable.Rows.OfType<DataRow>()
                .FirstOrDefault(x => x.ItemArray[2].ToString() == assemblyName);

            if (dataRow != null) 
            {
                dbProviderFactoriesDataTable.Rows.Remove(dataRow);
            }

            dbProviderFactoriesDataTable.Rows.Add(name, description, assemblyName, typeof(T).AssemblyQualifiedName);
        }
    }
}

Click()类的DBConnection方法创建MyDbContext的数据库上下文，并尝试向其中写入有关Book的信息。该方法分配给按钮的单击，执行该方法时会发生错误（在此行上：

db.Books.Add(book1);

完整代码：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Data.Entity;
using SQLite.CodeFirst;
using System.Configuration;
using System.Data.SQLite;
using System.Data.Common;

public class DBConnection : MonoBehaviour 
{
    // Use this for initialization
    void Start () {}

    public void Click()
    {
        using (DbConnection connection = new SQLiteConnection("FullUri=file::memory:")) 
        {
            connection.Open();

            using (var db = new MyDbContext(connection)) 
            {
                Book book1 = new Book { Name = "Граф Монтекристо", Price = 123 };
                db.Books.Add(book1);
                db.SaveChanges();
            }
        }
    }

    // Update is called once per frame
    void Update () {}
}

[DbConfigurationType(typeof(SqliteDbConfiguration))]
public class MyDbContext : DbContext
{
    private static readonly ConnectionStringSettings connectionString = new ConnectionStringSettings("localDataBase", "data source=.\\db.bytes", "System.Data.SQLite");

    static MyDbContext()
    {
        ConfigurationManager.ConnectionStrings.Add(connectionString);
        Configuration exeConfig = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
        Configuration machineConfig = ConfigurationManager.OpenMachineConfiguration();
    }

    public MyDbContext(DbConnection connection) : base(connection, false) 
    {
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        var sqliteConnectionInitializer = new SqliteCreateDatabaseIfNotExists<MyDbContext>(modelBuilder);
        Database.SetInitializer(sqliteConnectionInitializer);
    }

    public DbSet<Book> Books { get; set; }
}

public class Book
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Price { get; set; }
}

执行DBConnection.Click()时发生异常：

NotSupportedException：无法确定类型'System.Data.SQLite.SQLiteConnection'的连接的DbProviderFactory类型。确保已在应用程序配置中安装或注册了ADO.NET提供程序。

System.Data.Entity.Infrastructure.Net40DefaultDbProviderFactoryResolver + <> c__DisplayClass5.b__0（System.Type t）（在：0处）

System.Collections.Concurrent.ConcurrentDictionary 2[TKey,TValue].GetOrAdd (TKey key, System.Func 2 [T，TResult] valueFactory）（在：0处）

System.Data.Entity.Infrastructure.Net40DefaultDbProviderFactoryResolver.GetProviderFactory（System.Data.Common.DbConnection连接，System.Collections.Generic.IEnumerable`1 [T] dataRows）（在：0处）

System.Data.Entity.Infrastructure.Net40DefaultDbProviderFactoryResolver.ResolveProviderFactory（System.Data.Common.DbConnection连接）（位于：0）

System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderFactory（System.Data.Common.DbConnection连接）（位于：0）

System.Data.Entity.Core.Common.DbProviderServices.GetProviderFactory（System.Data.Common.DbConnection连接）（位于：0）

System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInvariantName（System.Data.Common.DbConnection连接）（位于：0）       System.Data.Entity.Internal.InternalConnection.get_ProviderName（）（在：0处）       System.Data.Entity.Internal.LazyInternalContext.get_ProviderName（）（：0处）       System.Data.Entity.Internal.DefaultModelCacheKeyFactory.Create（System.Data.Entity.DbContext上下文）（位于：0）       System.Data.Entity.Internal.LazyInternalContext.InitializeContext（）（在：0处）       System.Data.Entity.Internal.InternalContext.Initialize（）（在：0时）       System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType（System.Type实体类型）（位于：0）       System.Data.Entity.Internal.Linq.InternalSet 1[TEntity].Initialize () (at <f8fadb18f6a84dcf8e300a2f11995d19>:0) System.Data.Entity.Internal.Linq.InternalSet 1 [TEntity] .get_InternalContext（）（在：0处）       System.Data.Entity.Internal.Linq.InternalSet 1[TEntity].ActOnSet (System.Action action, System.Data.Entity.EntityState newState, System.Object entity, System.String methodName) (at <f8fadb18f6a84dcf8e300a2f11995d19>:0) System.Data.Entity.Internal.Linq.InternalSet 1 [TEntity] .Add（System.Object实体）（位于：0）       System.Data.Entity.DbSet 1[TEntity].Add (TEntity entity) (at <f8fadb18f6a84dcf8e300a2f11995d19>:0) DBConnection.Click () (at Assets/Scripts/PersonalCabinet/DBConnection.cs:21) UnityEngine.Events.InvokableCall.Invoke () (at C:/buildslave/unity/build/Runtime/Export/UnityEvent.cs:166) UnityEngine.Events.UnityEvent.Invoke () (at C:/buildslave/unity/build/Runtime/Export/UnityEvent_0.cs:58) UnityEngine.UI.Button.Press () (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/Button.cs:36) UnityEngine.UI.Button.OnPointerClick (UnityEngine.EventSystems.PointerEventData eventData) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/Button.cs:45) UnityEngine.EventSystems.ExecuteEvents.Execute (UnityEngine.EventSystems.IPointerClickHandler handler, UnityEngine.EventSystems.BaseEventData eventData) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/ExecuteEvents.cs:50) UnityEngine.EventSystems.ExecuteEvents.Execute[T] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.ExecuteEvents+EventFunction 1 [T1]仿函数）（在C：/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/ExecuteEvents.cs：261）       UnityEngine.EventSystems.EventSystem：Update（）

Answer 1

对于统一项目，请使用 Entity FrameWork Core （用于跨平台），而不要使用Entity FrameWork（不支持.NET Core）；还要确保统一的api级别是 .net标准2.0

无法在Unity中为SQLite配置实体框架

1 个答案: