如何改善此排序代码? [英] How can I improve this sorting code?

问题描述

我正在检查sort参数并构建一堆if语句:

I'm checking the sort parameter and building a bunch of if statements:

if (sortDirection == "ASC")
{
    if (sortBy == "Id")
        return customerList.OrderBy(x => x.Id).Skip(startIndex).Take(pageSize).ToList();
    if (sortBy == "FirstName")
        return customerList.OrderBy(x => x.FirstName).Skip(startIndex).Take(pageSize).ToList();
    if (sortBy == "City")
        return customerList.OrderBy(x => x.City).Skip(startIndex).Take(pageSize).ToList();
}
else
{
    if (sortBy == "Id")
        return customerList.OrderByDescending(x => x.Id).Skip(startIndex).Take(pageSize).ToList();
    if (sortBy == "FirstName")
        return customerList.OrderByDescending(x => x.FirstName).Skip(startIndex).Take(pageSize).ToList();
    if (sortBy == "City")
        return customerList.OrderByDescending(x => x.City).Skip(startIndex).Take(pageSize).ToList();
}

我该如何做得更好?

推荐答案

将您的订购与其余查询分开-无需在代码库中重复的每个查询的相同部分(请保留 DRY ):

Separate your ordering and the rest of the query - the parts that are the same for each query you don't have to duplicate in your codebase (keep it DRY):

var query = customerList;

if (sortDirection == "ASC")
{
    if (sortBy == "Id")
       query = query.OrderBy(x => x.Id);
    ///and so on
}

query = query.Skip(startIndex).Take(pageSize).ToList();

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