linq to sql使用crm早期绑定类

Question

我正在开发基于crm数据库的应用程序.我想使用linq to sql获取salesorder实体下的salesorderdetails数量.

我正在使用subselect查询.salesorder实体有new_sefer字段.我的疑问是

(from d in context.SalesOrderDetailSet
                where context.SalesOrderSet.Where(s => s.new_Sefer.Id == Id)
                .Select(i => i.SalesOrderId).Contains(d.SalesOrderId.Id)
                select d).Count();

它抛出异常.我还有关于子选择查询的问题

我如何使用linq编写这个SQL查询到SQL

select count(*) from salesorderdetail 
where salesorderId in (select salesorderId from salesorder 
                      where new_sefer = '750FEB6F-F742-E311-8F56-000C29F3049E')  

"无效'where'条件.实体成员正在调用无效的属性或方法."

在Microsoft.Xrm.Sdk.Linq.QueryProvider.FindValidEntityExpression(Expression exp,String operation)的Microsoft.Xrm.Sdk.Linq.QueryProvider.ThrowException(Exception exception)at Microsoft.Xrm.Sdk.Linq.QueryProvider.FindValidEntityExpression(Expression exp) ,字符串操作)在Microsoft.Xrm.Sdk.Linq.QueryProvider.TranslateWhereMethodCall(MethodCallExpression mce,FilterExpressionWrapper parentFilter,Func 2 getFilter, BinaryExpression parent, Boolean negate) at Microsoft.Xrm.Sdk.Linq.QueryProvider.TranslateWhereBoolean(String parameterName, Expression exp, FilterExpressionWrapper parentFilter, Func2 getFilter,List1 linkLookups, BinaryExpression parent, Boolean negate) at Microsoft.Xrm.Sdk.Linq.QueryProvider.TranslateWhere(QueryExpression qe, String parameterName, Expression exp, List 1 linkLookups)at Microsoft.Xrm.Sdk.Linq.QueryProvider.GetQueryExpression(Expression expression,Boolean&throwIfSequenceIsEmpty, Boolean&throwIfSequenceNotSingle,Projection&projection,NavigationSource&source,List1& linkLookups) at Microsoft.Xrm.Sdk.Linq.QueryProvider.Execute[TElement](Expression expression) at Microsoft.Xrm.Sdk.Linq.QueryProvider.System.Linq.IQueryProvider.Execute[TResult](Expression expression) at System.Linq.Queryable.Count[TSource](IQueryable1个源)在Xrm.SalesOrderDetailOperations.SelectSalesOrderDetailBySeferId(XrmServiceContext上下文中,的Guid Id)的在C:\ SVN \顾客\ Burulas\FlyDBOperations\FlyDBOperations\SalesOrderDetailOperations.cs:线26在FlyDBOperationsTest.SalesOrderDetailOperationsSalesOrderDetailOperationsTest.SelectSalesOrderDetailBySeferIdSelectSalesOrderDetailBySeferIdTest()在C:\ SVN\Customers\Burulas\FlyDBOperations\FlyDBOperationsTest\SalesOrderDetailOperationsSalesOrderDetailOperationsTest.cs:第82行

Answer 1

我相信这对你有用.

var count = (from d in context.SalesOrderDetailSet
                 join s in context.SalesOrderSet
                 on d.SalesOrderId.Id equals s.SalesOrderId
                 where s.new_Sefer.Id == Id
                 select d.SalesOrderId.Id).ToArray().Length;

Explination:

您正在编写的linq表达式实际上并没有转换为sql.它们被转换为CRM的查询API,因此您必须以CRM linq提供商可以解释的方式编写您的linq语句.这导致linq中存在的许多特性和方法不可用(如Count()).以下是SDK的链接,其中列出了linq支持的功能.

因此,查询将基于salesorderid将salesorderdeatil加入salesorder记录,salesorderid是salesorder实体的主键.然后在你的where子句中,你可以像你一样根据Id进行过滤.最后在select语句中我只选择了记录的ID.我这样做是因为它节省了带宽.如果不这样做,CRM将选择实体的每个属性,当您检索大文本字段时,它可能会导致性能问题.所以只检索你需要的东西.最后,由于不支持Count(),我只是将结果转换为数组并从中得到了长度.