情况是这样的。
我正在尝试使用 LINQ 在两个查询之间执行Union
。我已经使用匿名类型在两个查询中应用了GroupBy
。我不确切知道,但匿名类型的使用可能导致我遇到这个问题,我无法执行该联盟操作。它向我显示了这样的异常:
"System.Linq.IQueryable"不包含 "联合"的定义和最佳扩展方法重载 'System.Linq.ParallelEnumerable.Union(System.Linq.ParallelQuery, System.Collections.Generic.IEnumerable)' 有一些无效的 参数
这是查询:
var records = (from o in _context.Table1
join q in _context.Table2 on o.UserId equals q.UserId
group new { o, q }
by new { o.Name, o.Date, o.IsDone, o.IsDl, o.DateChanged, o.UserId, q.FirstName, q.LastName } into data
select new
{
NameP = data.Key.Name,
Date = data.Key.Date,
IsDone = data.Key.IsDone,
IsDl = data.Key.IsDl,
DateDone = data.Key.DateChanged,
Name = data.Key.FirstName +" "+ data.Key.LastName
}).Union(
from i in _context.Table1
where i.UserId == null
group i by new {o.Name, o.Date, o.IsDone, o.IsDl, o.DateChanged, o.UserId} into newData
select new
{
NameP = newData.Key.Name,
Date= newData.Key.Date,
IsDone = newData.Key.IsDone,
IsDl = newData.Key.IsDl,
DateDone = ' ',
Name = ' '
}).ToList();
我在这里试图实现的是获取两种情况的记录,当UserId
为空时,以及当它不为空时,使用 group by 因为记录是重复的。
感谢这里关于我做错了什么的任何建议或指导。
确保两个匿名类型对于所有属性具有相同的数据类型。
我唯一能推测的是日期的。也许第一个DateDone
实际上是DateTime
类型,而您将第二个设置为string
......
var records = (from o in _context.Table1
join q in _context.Table2 on o.UserId equals q.UserId
group new { o, q }
by new
{
o.Name,
o.Date,
o.IsDone,
o.IsDl,
o.DateChanged,
o.UserId,
q.FirstName,
q.LastName
} into data
select new
{
NameP = data.Key.Name,
Date = data.Key.Date,
IsDone = data.Key.IsDone,
IsDl = data.Key.IsDl,
DateDone = data.Key.DateChanged,
Name = data.Key.FirstName +" "+ data.Key.LastName
}).Union(from i in _context.Table1
where i.UserId == null
group i by new
{
o.Name,
o.Date,
o.IsDone,
o.IsDl,
o.DateChanged,
o.UserId
} into newData
select new
{
NameP = newData.Key.Name,
Date = newData.Key.Date,
IsDone = newData.Key.IsDone,
IsDl = newData.Key.IsDl,
DateDone = new DateTime(0),
Name = ' '
}).ToList();