Question

我有以下3个表格，如下所示。我试图在3个表中编写实体框架连接查询要追溯joblink, usersubmitted, runstatus, submitted_time, changelist orderby submitted time。

我有一个持有者类来返回输出...请注意，gerrits是一个List<string>，因为它可以为一次运行提供多个值，这是我得到错误的地方..，can任何人都提供了如何解决错误的指导，还是有更好的实践来实现这个目标？

持有人类： -

namespace Dashboard.Model.ApiModels
{
    public class LookaheadRunInfo
    {
        public string ECJobLink { get; set; }
        public List<String> changelists { get; set; }
        public string UserSubmitted { get; set; }
        public string SubmittedTime { get; set; }
        public string RunStatus { get; set; }
    }
}

API： -

    public IEnumerable<LookaheadRunInfo> GetLookaheadRunInfoSearch(LookaheadRunsFilterCriteria filterCriteria)
    {
        List<LookaheadRunInfo> lookaheadRunsInfo = new List<LookaheadRunInfo>();
        var lookaheadRunData = bitDB.lookahead_run.OrderByDescending(x => x.lookahead_run_id).Skip(filterCriteria.PageNumber * filterCriteria.PageSize).Take(filterCriteria.PageSize).ToList();
        foreach (var lookaheadRunRow in lookaheadRunData)
        {
            var lookaheadRunId = lookaheadRunRow.lookahead_run_id;
            var lookaheadRuns = new LookaheadRunInfo();
            lookaheadRuns = (from lrcl in bitDB.lookahead_run_change_list
                                             join cl in bitDB.change_lists on lrcl.change_list_id equals cl.change_list_id
                                             join lr in bitDB.lookahead_run on lrcl.lookahead_run_id equals lr.lookahead_run_id
                                             where lrcl.lookahead_run_id == lookaheadRunId
                                             orderby lr.submission_time
                                             select new LookaheadRunInfo
                                             {
                                                 ECJobLink = lr.ec_job_link,
                                                 //gerrits = cl.change_lists.Select(x => x.change_list.ToString()).ToList(),
                                                 changelists = cl.change_list.ToString(),
                                                 UserSubmitted = lr.submitted_by,
                                                 SubmittedTime =lr.submission_time.ToString(),
                                                 RunStatus = lr.lookahead_run_status,

                                             }).ToList();
            lookaheadRunsInfo.Add(lookaheadRuns);
        }
        return lookaheadRunsInfo;
    }

表： -

lookahead_run (Table#1) 
+-------------------+--------+----------------+-------------------+----------+
lookahead_run_id(PK)|joblink |  usersubmitted |submitted_time     |runstatus
+-------------------+--------+----------------+-------------------+----------+
15963---------------+link1---+---username1----+2017-03-17 22:28:53--Fail-----

lookahead_run_change_list (Table#2)
+---------------+----------------+-----------------+
changelistid(PK)|lookahead_run_id|change_list_id
+---------------+----------------+-----------------+
38591-----------+15963-----------+34022
38590-----------+15963-----------+34021
38589-----------+15963-----------+34020


change_lists (Table#3)
+-------------+-----------+
change_list_id|changelist
+-------------+-----------+
34022--------  1823900
34021--------  1819483
34020--------  1818572

错误： -

Error 1 Cannot implicitly convert type 'string' to 'System.Collections.Generic.List<string>'

Answer 1

看一下类定义，changelists被定义为List，现在看看查询，在这里你将cl.change_list.ToString()分配给List Of string。并且这是相同的错误消息说，您正在尝试将字符串值分配给字符串列表。

<强>修正

如果您确定changelists是列表的数据类型，请从查询中删除.ToString()，然后使用.ToList()。如果changelists是字符串，则表示在属性定义中进行必要的更改。

无法隐式转换类型＆＃39;字符串＆＃39; to＆＃39; System.Collections.Generic.List <string>＆＃39;`

1 个答案: