英文:
Error CS1061 'DateTime?' does not contain a definition for 'Date' and no accessible extension method 'Date'
问题
在我的ASP.NET Core Web API中，我有以下的代码。
public class PagingDto
{
public int PageSize { get; set; }
public int PageNumber { get; set; }
}
public class TransactionFilter : PagingDto
{
public DateTime? StartDate { get; set; }
public DateTime? EndDate { get; set; }
public string SearchQuery { get; set; }
}
public IQueryable<Transaction> GetAllTransactions(TransactionFilter filter)
{
var transactions = _context.Transactions
.Where(x => x.CreatedDate.Date >= filter.StartDate && x.CreatedDate.Date <= filter.EndDate)
.Where(x => string.IsNullOrEmpty(filter.SearchQuery) || x.Customer.Name.ToLower().Contains(filter.SearchQuery.ToLower())
|| x.Payment.Status.ToLower().Contains(filter.SearchQuery.ToLower())
|| x.Payment.TransactionReference.ToLower().Contains(filter.SearchQuery.ToLower())
|| x.Payment.MethodOfPayment.ToLower().Contains(filter.SearchQuery.ToLower())
|| x.Payment.Amount.ToString().Contains(filter.SearchQuery))
.Include(b => b.Payment)
.Include(b => b.Customer)
.OrderByDescending(transaction => transaction.CreatedDate);
return transactions;
}
我想查询所有在StartDate和EndDate之间使用CreatedDate的交易。
但是我得到了这个错误：
错误 CS1061：'DateTime?'不包含名称为'Date'的定义，也没有找到可接受第一个参数类型为'DateTime?'的扩展方法'Date'（您是否缺少using指令或程序集引用？）
然后在这行中，Date 被突出显示：
.Where(x => x.CreatedDate.Date >= filter.StartDate && x.CreatedDate.Date <= filter.EndDate)
如何解决这个问题？
英文:
In my ASP.NET Core Web API, I have this code.
public class PagingDto
{
public int PageSize { get; set; }
public int PageNumber { get; set; }
}
public class TransactionFilter : PagingDto
{
public DateTime? StartDate { get; set; }
public DateTime? EndDate { get; set; }
public string SearchQuery { get; set; }
}
GetAllTransactions
public IQueryable<Transaction> GetAllTransactions(TransactionFilter filter)
{
var transactions = _context.Transactions
.Where(x => x.CreatedDate.Date >= filter.StartDate && x.CreatedDate.Date <= filter.EndDate)
.Where(x => string.IsNullOrEmpty(filter.SearchQuery) || x.Customer.Name.ToLower().Contains(filter.SearchQuery.ToLower())
|| x.Payment.Status.ToLower().Contains(filter.SearchQuery.ToLower())
|| x.Payment.TransactionReference.ToLower().Contains(filter.SearchQuery.ToLower())
|| x.Payment.MethodOfPayment.ToLower().Contains(filter.SearchQuery.ToLower())
|| x.Payment.Amount.ToString().Contains(filter.SearchQuery))
.Include(b => b.Payment)
.Include(b => b.Customer)
.OrderByDescending(transaction => transaction.CreatedDate);
return transactions;
}
I want to Query all transactions that falls between StartDate and EndDate using CreatedDate.
But I got thus error:
Severity Code Description Project File Line Suppression State
Error CS1061 'DateTime?' does not contain a definition for 'Date' and no accessible extension method 'Date' accepting a first argument of type 'DateTime?' could be found (are you missing a using directive or an assembly reference?)
Then Date is highlighted in
.Where(x => x.CreatedDate.Date >= filter.StartDate && x.CreatedDate.Date <= filter.EndDate)
How do I resolve this?
答案1
得分: 0
DateTime? 相当于 Nullable<DateTime>。
Nullable<T> 没有 .Date 属性。
你应该写：
x.CreatedDate.Value.Date
但是你应该记住，x.CreatedDate 在运行时可能为 null。在这种情况下，你将会得到一个 NullReferenceExpection。
所以，你的逻辑应该支持这种情况，并应包含额外的检查，以确保在 x.CreatedDate 为 null 时不调用 x.CreatedDate.Value.Date。
有用的链接：
英文:
DateTime? is an equivalent of Nullable<DateTime>.
Nullable<T> doesn't have a property .Date.
You should write:
x.CreatedDate.Value.Date
But you should keep in mind that x.CreatedDate can be null in the runtime. In that case, youll get a NullReferenceExpection`.
So, your logic should support such a case and should contain additional checks not to call x.CreatedDate.Value.Date when x.CreatedDate is null.
> Useful links:
> - https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/nullable-value-types
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