我正在创建一个内部 Razor Pages 应用程序,它使用实体框架连接到 SQL 数据库。我有一个带有搜索表单的页面,我希望能够根据输入的日期搜索记录。
这是我到目前为止所拥有的:
public async Task OnGetAsync(string searchString)
{
// provide an IQueryable list of web registrants that can be parsed.
// IQueryable<Models.WebPestMSTR> webRegistrationIQ = (from a in _context.WebPestMSTR
// select a);
// If the Search string is empty than only show the unprocessed web registration. Otherwise parse the table for matching records.
if (!String.IsNullOrEmpty(searchString))
{
// There is a search parameter. Parse the query for matching records.
// Parse the search parameter to see if it is a date (bool isCertNo = BigInteger.TryParse(searchString, out numOut);)
if (DateTime.TryParse(searchString, out DateTime dateTime))
{
WebPestMSTR = await _context.WebPestMSTR
.Where(a => a.DateAdded.ToShortDateString() == dateTime.ToShortDateString())
.Include(w => w.Course)
.Include(w => w.MiraInfo)
.ToListAsync();
// webRegistrationIQ = webRegistrationIQ.Where(a => a.DateAdded.ToShortDateString() == dateTime.ToShortDateString());
}
else
{
IQueryable<Models.WebPestMSTR> webRegistrationIQ = (from a in _context.WebPestMSTR
select a);
webRegistrationIQ = webRegistrationIQ.Where(a => a.LastName.Contains(searchString));
WebPestMSTR = await webRegistrationIQ
.Include(w => w.Course)
.Include(w => w.MiraInfo)
.ToListAsync();
}
}
else
{
// No search parameters so only show unprocessed records.
WebPestMSTR = await _context.WebPestMSTR
.Include(w => w.Course)
.Include(w => w.MiraInfo)
.Where(w => w.IsProcessed == false)
.ToListAsync();
}
}
如果它是日期,我能够成功解析 searchString,但在何处出错。错误是:
InvalidOperationException:无法翻译 LINQ 表达式“DbSet .Where(w => w.DateAdded.ToShortDateString() == __ToShortDateString_0)”。以可翻译的形式重写查询,或通过插入对 AsEnumerable()、AsAsyncEnumerable()、ToList() 或 ToListAsync() 的调用显式切换到客户端评估。
当按姓氏搜索时,搜索工作正常。
有什么想法吗?
如果您只需要比较日期(没有时间)并且您使用的是 ms sql server,您可以尝试
WebPestMSTR = await _context.WebPestMSTR
.Where(a => EF.Functions.DateDiffDay(a.DateAdded, dateTime)==0)
.Include(w => w.Course)
.Include(w => w.MiraInfo)
.ToListAsync();
如果您需要更多的大小比较,您可以使用 EF.Functions.DateDiffMinute 或 EF.Functions.DateDiffSecond 代替。此函数包含在 Microsoft.EntityFrameworkCore.SqlServer nuget 包中。
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