Question

我的字符串包含用于使用linq进行排序的列名，当字符串只包含一列时，它工作正常，但是当包含多列时，我不知道如何创建linq语句来对它们进行排序。

我的字符串是这样的：“ClassNo ASC，count DESC，floor ASC” 如果有一栏，我会尝试如下排序：

 switch (sort.Trim())
            {
                default:
                    result = result.OrderBy(u => u.ClassId);
                    break;
                case "ClassNo DESC":
                    result = result.OrderByDescending(u => u.ClassNo);
                    break;
                case "ClassNo ASC":
                    result = result.OrderBy(u => u.ClassNo);
                    break;
                case "count DESC":
                    result = result.OrderByDescending(u => u.count);
                    break;
                case "count ASC":
                    result = result.OrderBy(u => u.count);
                    break;
                case "floor DESC":
                    result = result.OrderByDescending(u => u.floor);
                    break;
                case "floor ASC":
                    result = result.OrderBy(u => u.floor);
                    break;
                case "ClassId DESC":
                    result = result.OrderByDescending(u => u.ClassId);
                    break;
            }

Answer 1

您可以这样做：

var ordered1 = result.OrderBy(x => x.count);
var ordered2 = ordered1.ThenBy(x => x.floor);
var ordered3 = ordered2.ThenByDescending(x => x.ClassId);

此处需要注意的是OrderBy()或OrderByDescending()会返回IOrderedEnumerable<T>，然后您可以添加其他级别的订单。

所以在你的情况下，它会是这样的：

// convert to an IOrderedEnumerable<T>
var orderedResult = result.OrderBy(x => 1);

foreach (string part in sort.Split(','))
{
    switch (part.Trim())
    {
        case "ClassNo DESC":
            orderedResult = orderedResult.ThenByDescending(u => u.ClassNo);
            break;
        case "ClassNo ASC":
            orderedResult = orderedResult.ThenBy(u => u.ClassNo);
            break;
        case "count DESC":
            orderedResult = orderedResult.ThenByDescending(u => u.count);
            break;
        case "count ASC":
            orderedResult = orderedResult.ThenBy(u => u.count);
            break;
        case "floor DESC":
            orderedResult = orderedResult.ThenByDescending(u => u.floor);
            break;
        case "floor ASC":
            orderedResult = orderedResult.ThenBy(u => u.floor);
            break;
        case "ClassId DESC":
            orderedResult = orderedResult.ThenByDescending(u => u.ClassId);
            break;
        default:
            orderedResult = orderedResult.ThenBy(u => u.ClassId);
            break;
    }
}

linq的多个orderby字符串列

1 个答案: