[英]Xrm.Sdk Linq with Joins and dynamic where
After a bunch of time getting my query syntactically correct it looks like the the sdk has some limitations.. i also tried a sub query with facility but it returned a IQuery (i or something).经过一段时间让我的查询在语法上正确无误,sdk 似乎有一些限制。 Is there a way to achieve a dynamic where clause in a Linq Xrm Query有没有办法在 Linq Xrm 查询中实现动态 where 子句
the exception thrown抛出的异常
System.NotSupportedException: The method 'Where' cannot follow the method 'Select' or is not supported. System.NotSupportedException:方法“Where”不能遵循方法“Select”或不受支持。 Try writing the query in terms of supported methods or call the 'AsEnumerable' or 'ToList' m ethod before calling unsupported methods.尝试根据支持的方法编写查询,或者在调用不受支持的方法之前调用“AsEnumerable”或“ToList”方法。
var predicate = PredicateBuilder.New<GetAllResult>(false);
if (query?.ObservationOnStart != null && query?.ObservationOnEnd != null)
{
predicate.And(result =>
result.ObservationEntity.esor_ObservationOn >= query.ObservationOnStart &&
result.ObservationEntity.esor_ObservationOn <= query.ObservationOnEnd);
}
var queryable = from observationEntity in _ctx.esor_ObservationSet
join facilityEntity in _ctx.core_FacilitySet
on observationEntity.esor_Facility.Id equals facilityEntity.Id
orderby observationEntity.esor_ObservationOn
select new GetAllResult {ObservationEntity = observationEntity, FacilityEntity = facilityEntity}
;
// THIS throws exception
queryable.Where(predicate).ToList();
I have also tried checking the a varable and used and OR but it also throws an exception我也试过检查变量和使用的和或但它也抛出异常
where completedById.Equals(null) || observationEntity.esor_CompletedBy.Id.Equals(completedById)
System.NotSupportedException: Invalid 'where' condition. System.NotSupportedException: 无效的“where”条件。 An entity member is invoking an invalid property or method实体成员正在调用无效的属性或方法
In your first code snippet, you first call:在您的第一个代码片段中,您首先调用:
select new GetAllResult
and then进而
queryable.Where(predicate)
which doesn't work.这不起作用。 because - as you've find out - you can't call where
after calling select
.因为 - 正如你所发现的 - 在调用select
之后你不能调用where
。
Then, in your second code snippet, you call:然后,在您的第二个代码片段中,您调用:
where completedById.Equals(null)
Which doesn't work because the left hand side of the where clause has to be an entity attribute name, while completedById
is apparently a variable you've delcared somewhere.这不起作用,因为where子句的左侧必须是一个实体的属性名称,而completedById
显然你已经delcared地方的变量。
CRM Dynamics's Linq queries must be kept pretty simple, and if you insist on using Linq (and not, say, QueryExpression
), do as follows: CRM Dynamics 的 Linq 查询必须保持非常简单,如果您坚持使用 Linq(而不是QueryExpression
),请执行以下操作:
// ... build you queryable, and then:
// 1. first, call ToList()
var records = queryable.ToList();
// 2. then, filter it with Where()
if (query?.ObservationOnStart != null && query?.ObservationOnEnd != null)
{
records = records.Where(r =>
r.ObservationEntity.esor_ObservationOn >= query.ObservationOnStart &&
r.ObservationEntity.esor_ObservationOn <= query.ObservationOnEnd
).ToList();
}
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