Xrm.Sdk Linq with Joins and dynamic where

Question

经过一段时间让我的查询在语法上正确，看起来 sdk 有一些限制.. 我也尝试了一个带有 facility 的子查询，但它返回了一个 IQuery（i 或其他东西）。有没有办法在 Linq Xrm 查询中实现动态 where 子句

抛出异常

System.NotSupportedException: The method 'Where' cannot follow the method 'Select' or is not supported. Try writing the query in terms of supported methods or call the 'AsEnumerable' or 'ToList' m ethod before calling unsupported methods.

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();

我也试过检查变量并使用和 OR 但它也抛出异常

where completedById.Equals(null) || observationEntity.esor_CompletedBy.Id.Equals(completedById)

System.NotSupportedException: Invalid 'where' condition. An entity member is invoking an invalid property or method

Answer 1

在您的第一个代码片段中，您首先调用：

select new GetAllResult

然后是

queryable.Where(predicate)

这是行不通的。因为 - 正如您所发现的 - 您不能在调用 select 之后调用 where。

然后，在您的第二个代码片段中，您调用：

where completedById.Equals(null)

这不起作用，因为 where 子句的左侧必须是实体属性名称，而 completedById 显然是您在某处指定的变量。

CRM Dynamics 的 Linq 查询必须非常简单，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();
}

Xrm.Sdk Linq with Joins and dynamic where

Xrm.Sdk Linq with Joins and dynamic where

c#

linq

dynamics-crm

xrm