C# 带有语句体的 lambda 表达式无法在 nopCommerce 中转换为表达式树
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A lambda expression with a statement body cannot be converted to an expression tree in nopCommerce
提问by Ragesh S
I try to create a linq join query in the nopCommerce 3.0. i join two table in linq and write
我尝试在 nopCommerce 3.0 中创建一个 linq 连接查询。我在 linq 中加入两个表并写
the code successfully. but the visual studio intellicence shows the error like
代码成功。但是视觉工作室的智能显示了这样的错误
A lambda expression with a statement body cannot be converted to an expression tree
带有语句体的 lambda 表达式无法转换为表达式树
please see my code below
请看下面我的代码
var roles = _customerEventRoleRepository.Table.Where(c => c.EventId == selevent)
.Join
(
_customerRepository.Table,
cev => cev.CustomerId, c => c.Id,
(cev, c) =>
{
var cust = new CustomerEventRolesModel();
cust.Id = cev.Id;
cust.CustomerId = c.Id;
cust.Customer = c.Email;
cust.ContactName = c.GetAttribute<string>(SystemCustomerAttributeNames.FirstName);
cust.CompanyName = c.GetAttribute<string>(SystemCustomerAttributeNames.Company);
cust.Speaker = cev.IsSpeaker;
cust.Sponsor = cev.IsSponser;
return cust;
}
).OrderBy(cev => cev.Customer).ToList();
but the error shows
但错误显示
please help
请帮忙
采纳答案by jason
The error message is exactlywhat it says. You have a lambda expression. It has a statement body. A lambda expression with a statement body can not be converted to an expression tree. But Joinrequires an expression tree to use with EF. You should try replacing what you have with a lambda expression that doesn't have a body like:
错误消息正是它所说的。你有一个 lambda 表达式。它有一个声明主体。带有语句体的 lambda 表达式不能转换为表达式树。但是Join需要一个表达式树来与 EF 一起使用。您应该尝试用一个没有正文的 lambda 表达式替换您拥有的内容，例如：
(cev, c) => new CustomerEventRolesModel {
Id = cev.Id,
CustomerId = c.Id
}
And so on.
等等。
By the way,
顺便一提，
ContactName = c.GetAttribute<string>(SystemCustomerAttributeNames.FirstName)
will NOT work with EF. Period. You better figure something else out.
不会与 EF 一起使用。时期。你最好想办法。
