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IObjectSet包含CompiledQuery的扩展方法错误

ef-code-first entity-framework-4 c#

Paul · 技术社区 · 15 年前

在我的自定义ObjectContext类中,我将实体集合公开为IObjectSet,以便对它们进行单元测试。当我在编译的查询中使用这个ObjectContext并调用“Include”扩展方法(来自Julie Lerman的博客)时遇到了一个问题 http://thedatafarm.com/blog/data-access/agile-entity-framework-4-repository-part-5-iobjectset/ )在她的书《编程实体框架》第二版第722-723页。代码如下:

查询:

public class CommunityPostsBySlugQuery : QueryBase<IEnumerable<CommunityPost>>
    {
        private static readonly Expression<Func<Database, string, IEnumerable<CommunityPost>>> expression = (database, slug) => database.CommunityPosts.Include("Comments").Where(x => x.Site.Slug == slug).OrderByDescending(x => x.DatePosted);
        private static readonly Func<Database, string, IEnumerable<CommunityPost>> plainQuery = expression.Compile();

        private static readonly Func<Database, string, IEnumerable<CommunityPost>> compiledQuery = CompiledQuery.Compile(expression);

        private readonly string _slug;
        public CommunityPostsBySlugQuery(bool useCompiled, string slug): base(useCompiled)
        {
            _slug = slug;
        }

        public override IEnumerable<CommunityPost> Execute(Database database)
        {
            return base.UseCompiled ? compiledQuery(database, _slug) : plainQuery(database, _slug);
        }
    }

延伸

public static class ObjectQueryExtension
    {
        public static IQueryable<T> Include<T>(this IQueryable<T> source, string path)
        {
            var objectQuery = source as ObjectQuery<T>;
            return objectQuery == null ? source : objectQuery.Include(path);
        }
    }

LINQ to实体无法识别方法“System.LINQ.IQueryable1[MyPocoObject]Include[myincludedpooobject](System.LINQ.IQueryable1[MyPocoObject],System.String)”方法,并且此方法无法转换为存储表达式。

如果我在ObjectSet集合上使用相同的查询,而不是IObjectSet,那么它可以正常工作。如果我只是运行这个查询而不进行预编译,它就可以正常工作。我错过了什么?