Question

我有一个Of Of Of List和id，想查询带有多个参数的列表，以减少搜索页面上的结果。

     int SecLink = (!string.IsNullOrEmpty(Request.QueryString["Sector"])) ? Convert.ToInt32(Request.QueryString["Sector"]) : 0;
        int LocLink = (!string.IsNullOrEmpty(Request.QueryString["Location"])) ? Convert.ToInt32(Request.QueryString["Location"]) : 0;
        int IndLink = (!string.IsNullOrEmpty(Request.QueryString["Industry"])) ? Convert.ToInt32(Request.QueryString["Industry"]) : 0;
        int VacLink = (!string.IsNullOrEmpty(Request.QueryString["Vacancy"])) ? Convert.ToInt32(Request.QueryString["Vacancy"]) : 0;

        string keyword = Request.QueryString["SearchTerm"];

        var dx = new DataX();
        var lstJobs = dx.GetAllJobs().Where(x => x.SectorLink.Equals(SecLink) && x.LocationLink.Equals(LocLink) && x.IndustryLink.Equals(IndLink) && x.VacancyTypeLink.Equals(VacLink) && x.JobName.Contains(keyword)).ToList();

        if (lstJobs.Count > 0)
        {
            uiRptSearchJobs.DataSource = lstJobs;
            uiRptSearchJobs.DataBind();

            uiLitSearchResults.Text = string.Format("<h4>Search result found {0} matches</h4>", lstJobs.Count);
        }

搜索参数可能是＆＃39; 0＆＃39;由于没有从上一页中选择，所以结果应该反映他的。

这是我传递的查询字符串：

Default.aspx?section=search&Sector=4&Location=0&Industry=0&Vacancy=0&SearchTerm=

但正如您所看到的，它们的查询字符串将随用户从上一页中选择的内容而改变。

Answer 1

如果我理解正确，如果参数值为0，您不想过滤？如果是这样，有两个解决方案：

检查条件中参数是否等于0：

var lstJobs = dx.GetAllJobs().Where(x => 
    (SecLink == 0 || x.SectorLink.Equals(SecLink))
    && (LocLink == 0 || x.LocationLink.Equals(LocLink))
    && (IndLink == 0 || x.IndustryLink.Equals(IndLink))
    && (VacLink == 0 || x.VacancyTypeLink.Equals(VacLink))
    && x.JobName.Contains(keyword)).ToList();

Linq善良，动态构建您的查询：

    var query = dx.GetAllJobs().Where(x => x.JobName.Contains(keyword));

    if (SecLink != 0)
    {
        query = query.Where(x => x.SectorLink.Equals(SecLink));
    }

    if (LocLink != 0)
    {
        query = query.Where(x => x.LocationLink.Equals(LocLink));
    }

    if (IndLink != 0)
    {
        query = query.Where(x => x.IndustryLink.Equals(IndLink));
    }

    if (VacLink != 0)
    {
        query = query.Where(x => x.VacancyTypeLink.Equals(VacLink));
    }

    var lstJobs = query.ToList();

Answer 2

一种选择是有条件地执行Where条款：

如果搜索字词应该一起进行AND运算：

var lstJobs = dx.GetAllJobs();

if (SecLink > 0)
    lstJobs = lstJobs.Where(x => x.SectorLink.Equals(SecLink))

if (LocLink > 0)
    lstJobs = lstJobs.Where(x => x.LocationLink.Equals(LocLink))

if (IndLink > 0)
    lstJobs = lstJobs.Where(x => x.IndustryLink.Equals(IndLink))

if (VacLink > 0)
    lstJobs = lstJobs.Where(x => x.VacationLink.Equals(VacLink))

// Performance does not suffer because the query will
// not get evaluated until it's required. For example, 
// here we call .ToList, which forces the query to be evaluated.
var result = lstJobs.ToList();

但是，您已明确表示您需要将搜索字词ORed放在一起。在那种情况下：

var lstJobs = dx.GetAllJobs().Where(x => x.JobName.Contains(keyword));

if (SecLink > 0)
    lstJobs = lstJobs.Union(
        dx.GetAllJobs().Where(x => x.SectorLink.Equals(SecLink))

if (LocLink > 0)
    lstJobs = lstJobs.Union(
        dx.GetAllJobs().Where(x => x.LocationLink.Equals(LocLink))

etc...

Lambda或Linq方法搜索多个参数

2 个答案: