数据无法获取。linq+；谓语

我写了一个扩展名。这个扩展的过滤机制是翻转谓词对象。但是，我有个问题

    public static IQueryable<T> Filter<T>(this IQueryable<T> data, FilterGroupExpression filter)
    {
        var source = data;

        Expression<Func<T, bool>> predicate;

        if (filter.Operator == FilterGroupOperators.And)
            predicate = PredicateBuilder.True<T>();
        else
            predicate = PredicateBuilder.False<T>();

        foreach (FilterRuleDescriptive ruleExp in filter.Rules)
        {
            if (filter.Operator == FilterGroupOperators.And)
                predicate = predicate.And<T>(MakeExpression<T>(ruleExp));
            else
                predicate = predicate.Or<T>(MakeExpression<T>(ruleExp));
        }

        foreach (FilterGroupExpression groupExp in filter.Groups)
        {
            if (filter.Operator == FilterGroupOperators.And)
                predicate = predicate.And<T>(SubGroupFilter<T>(groupExp));
            else
                predicate = predicate.Or<T>(SubGroupFilter<T>(groupExp));
        }

        return source.Where(predicate);
    }

    public static Expression<Func<T, bool>> SubGroupFilter<T>(FilterGroupExpression filter)
    {

        Expression<Func<T, bool>> predicate;

        if (filter.Operator == FilterGroupOperators.And)
            predicate = PredicateBuilder.True<T>();
        else
            predicate = PredicateBuilder.False<T>();

        foreach (FilterRuleDescriptive ruleExp in filter.Rules)
        {
            if (filter.Operator == FilterGroupOperators.And)
                predicate = predicate.And<T>(MakeExpression<T>(ruleExp));
            else
                predicate = predicate.Or<T>(MakeExpression<T>(ruleExp));
        }

        foreach (FilterGroupExpression groupExp in filter.Groups)
        {
            predicate = SubGroupFilter<T>(groupExp);
        }

        return predicate;
    }

    public static Expression<Func<T, bool>> MakeExpression<T>(FilterRuleDescriptive condition)
    {
        Expression currentExpr = null;
        var param = Expression.Parameter(typeof(T), "param");
        var prop = Expression.Property(param, condition.Field);
        var propType = Nullable.GetUnderlyingType(prop.Type) ?? prop.Type;
        ConstantExpression constant = null;


        condition.Value = Convert.ChangeType(condition.Value, propType);

        if (IsNullableType(prop.Type))
            constant = Expression.Constant(condition.Value.ConvertToNullable<int>(), prop.Type);
        else
            constant = Expression.Constant(condition.Value, propType);

        if (condition.Value.GetType() == typeof(string))
            condition.Value = condition.Value.ToString().Replace("'", string.Empty);


        switch (condition.Operator)
        {
            case FilterRuleOperator.Equals:
                currentExpr = Expression.Equal(prop, constant);
                break;
            case FilterRuleOperator.DoesNotEqual:
                currentExpr = Expression.NotEqual(prop, constant);
                break;
            case FilterRuleOperator.StartsWith:
                currentExpr = Expression.Call(prop, typeof(string).GetMethod("StartsWith", new[] { typeof(string) }), constant);
                break;
            case FilterRuleOperator.EndsWith:
                currentExpr = Expression.Call(prop, typeof(string).GetMethod("EndsWith", new[] { typeof(string) }), constant);
                break;
            case FilterRuleOperator.Contains:
                currentExpr = Expression.Call(prop, typeof(string).GetMethod("Contains", new[] { typeof(string) }), constant);
                break;
            case FilterRuleOperator.IsGreaterThan:
                currentExpr = Expression.GreaterThan(prop, constant);
                break;
            case FilterRuleOperator.IsGreaterThanOrEqual:
                currentExpr = Expression.GreaterThanOrEqual(prop, constant);
                break;
            case FilterRuleOperator.IsLessThan:
                currentExpr = Expression.LessThan(prop, constant);
                break;
            case FilterRuleOperator.IsLessThanOrEqual:
                currentExpr = Expression.LessThanOrEqual(prop, constant);
                break;
            case FilterRuleOperator.IsNull:
                currentExpr = Expression.Equal(prop, constant);
                break;
            case FilterRuleOperator.IsNotNull:
                currentExpr = Expression.NotEqual(prop, constant);
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }

        return Expression.Lambda<Func<T, bool>>(currentExpr, param);
    }

当LinQ询问时，0转换数据

result.Count（）=0

有什么问题吗？

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请帮帮我…：（

检查您的程序是否使用了正确的数据库，然后使用Sql Profiler查看正在执行的Sql。我从未使用过Sql Profiler。我从sqlprofiler中观察到了问题。非常感谢您的帮助…：）

SELECT [t0].[Id], [t0].[Name], [t0].[SmallDescription], [t0].[Description], [t0].[Barcode], [t0].[CategoryId], [t0].[Code], [t0].[PurchasePrice], [t0].[Price], [t0].[OldPrice], [t0].[VatRatio], [t0].[MetaDescription], [t0].[MetaKeywords], [t0].[VariantFirstTypeId], [t0].[VariantSecondTypeId], [t0].[MarkId], [t0].[Mark], [t0].[Stok], [t0].[ShowCase], [t0].[Firm], [t0].[IsVariant], [t0].[IsValid], [t0].[IsSale] FROM [dbo].[Product] AS [t0] WHERE ([t0].[Code] LIKE @p0) AND ([t0].[Name] LIKE @p1) AND ([t0].[Price] >= @p2) AND ([t0].[Price] < @p3) AND (([t0].[SmallDescription] LIKE @p4) OR ([t0].[SmallDescription] LIKE @p5))

var result = source.Where(predicate);