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我收到此错误：

DbSortClause 表达式必须具有顺序可比的类型。参数名称：key | 在 System.Data.Common.CommandTrees.ExpressionBuilder.Internal.ArgumentValidation.ValidateSortClause(DbExpression key) 在 System.Data.Common.CommandTrees.ExpressionBuilder.DbExpressionBuilder.ToSortClause(DbExpression key) 在 System.Data.Objects.ELinq.ExpressionConverter.MethodCallTranslator .OrderByTranslatorBase.TranslateOneLambda(ExpressionConverter parent, DbExpressionBinding sourceBinding, DbExpression lambda) at System.Data.Objects.ELinq.ExpressionConverter.MethodCallTranslator.OneLambdaTranslator.Translate(ExpressionConverter parent, MethodCallExpression call, DbExpression& source, DbExpressionBinding& sourceBinding, DbExpression& lambda) at System.Data .Objects.ELinq.ExpressionConverter.MethodCallTranslator.OneLambdaTranslator。1.Translate(ExpressionConverter parent, Expression linq) at System.Data.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq) at System.Data.Objects.ELinq.ExpressionConverter.Convert() at System.Data.Objects.ELinq.ELinqQueryState.GetExecutionPlan(Nullable1 forMergeOption) 在 System.Data.Objects.ObjectQuery 1.GetResults(Nullable1 forMergeOption) 在 System.Data.Objects.ObjectQuery 1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() at System.Data.Entity.Internal.Linq.InternalQuery1.GetEnumerator() 在 System.Data.Entity.Infrastructure.DbQuery 1.System.Collections.Generic.IEnumerable<TResult>.GetEnumerator() at System.Collections.Generic.List1..ctor(IEnumerable 1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable1 source) 在 MvcMusicStore.Controllers .StoreManagerController.Index(String sortOrder) 在

尝试此代码时

var albums = db.Albums.Include(a => a.Genre).Include(a => a.Artist);

            switch (sortOrder) {
                case "Artist desc":
                    albums = albums.OrderByDescending(o => o.Artist);
                    break;
                case "Title desc":
                    albums = albums.OrderByDescending(o => o.Title);
                    break;
                case "Title":
                    albums = albums.OrderBy(o => o.Title);
                    break;
                case "Genre desc":
                    albums = albums.OrderByDescending(o => o.Genre);
                    break;
                case "Genre":
                    albums = albums.OrderBy(o => o.Genre);
                    break;
                default:
                    albums = albums.OrderBy(o => o.Artist);
                    break;
            }

            return View(albums.ToList());

我找不到对其进行排序的方法。

4

1 回答 1

4

你说.Include(a => a.Artist);的也一样.OrderByDescending(o => o.Artist);。如果您尝试按会导致错误的对象进行排序。 Artist你可能想要这样的东西：

albums = albums.OrderByDescending(o => o.Artist.Name);

我假设 anArtist有一个Stringproperty Name，但也许它被称为不同的东西。同样适用于Genre：

albums = albums.OrderByDescending(o => o.Genre.Name);

通常，您需要按原始值而不是整个对象进行排序。

于 2013-01-16T14:02:51.353 回答