EntityFramework进阶（三）- 根据IQueryable获取DbContext

本系列原创博客代码已在EntityFramework6.0.0测试通过，转载请标明出处

有时候我们要通过IQueryable获取所在的DbContext信息，这是完全可以的。

以下代码从个人开源框架中抽取而出

using System;

using System.Data.Entity;

using System.Data.Entity.Core.Objects;

using System.Data.Entity.Infrastructure;

using System.Data.Entity.Infrastructure.Interception;

using System.Linq;

using System.Reflection;

/*

* CopyRight ©2017 All Rights Reserved

* 作者:Rex Sheng

*/

namespace SuperNet.EntityFramework.Extensions

{

    public static class IQueryableExtensions

    {

        public static DbContext GetDbContext<TEntity>(this IQueryable<TEntity> query) where TEntity : class

        {

            ObjectQuery<TEntity> objectQuery = null;

            DbQuery<TEntity> dbQuery = null;

            if(query is ObjectQuery<TEntity>)

            {

                objectQuery = (ObjectQuery<TEntity>)query;

            }

            else

            {

                if(query is DbQuery<TEntity>)

                {

                    dbQuery = (DbQuery<TEntity>)query;

                    var propers = dbQuery.GetType().GetProperty("InternalQuery", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);

                    if (propers == null)

                    {

                        throw new Exception("未能从IQueryable表达式找到DbContext。您确定此表达式来自Ef DbContext吗?");

                    }

                    var obj = propers.GetValue(dbQuery, null);

                    propers = obj.GetType().GetProperty("ObjectQuery", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);

                    if (propers == null)

                    {

                        throw new Exception("未能从IQueryable表达式找到DbContext。您确定此表达式来自Ef DbContext吗?");

                    }

                    objectQuery = propers.GetValue(obj, null) as ObjectQuery<TEntity>;

                    if (objectQuery == null)

                    {

                        throw new Exception("未能从IQueryable表达式找到DbContext。您确定此表达式来自Ef DbContext吗?");

                    }

                }

                else

                {

                    throw new Exception("未能从IQueryable表达式找到DbContext。您确定此表达式来自Ef DbContext吗?");

                }

            }

            return objectQuery.Context.GetDbContext();

        }

    }

}