检索 N:N 关系 Dynamics CRM

Question

我在内部部署的 Dynamics 2016 中的机会和我的自定义合同实体之间存在关系。我正在尝试从 C# 插件中的特定机会检索所有相关合同。当我尝试检索关系时，收到错误：

No system many-to-many relationship exists between opportunity and ccseq_contract. If attempting to link through a custom many-to-many relationship ensure that you provide the from and to attributes.

根据此屏幕截图看来关系确实存在：

这是我的查询表达式：

EntityCollection contracts = service.RetrieveMultiple(new QueryExpression()
{
    EntityName = Opportunity.LogicalName,
    ColumnSet = new ColumnSet(new String[]
    {
        Opportunity.Properties.OpportunityId
    }),
    LinkEntities =
    {
        new LinkEntity
        {
            LinkFromEntityName = Opportunity.LogicalName,
            LinkToEntityName = Contract.LogicalName,
            LinkCriteria = new FilterExpression
            {
                FilterOperator = LogicalOperator.And,
                Conditions =
                {
                    new ConditionExpression
                    {
                        AttributeName = Opportunity.Properties.OpportunityId,
                        Operator = ConditionOperator.Equal,
                        Values = {wonOpportunity.Id}
                    }
                }
            }
        }
    }
});

为什么我会收到此错误以及如何解决该错误？

Answer 1

查询表达式中的 LinkedEntity 与 SQL 内部或外部联接完全相同（您指定联接类型）。它非常适合获取 N:1 关系，但它不适用于 N:N。

对于 N:N，您需要通过 'relationship entity'。

如果您希望所有合同都链接到一个机会，您必须在 'relationship entity' table、'ccseq_opportunity_ccseq_contract' 中检索具有将他们链接到该机会的行的所有联系人（我在下面使用字符串常量，因为我不太清楚如何您正在构建您的实体类)。

var q = new QueryExpression("ccseq_contract") {
    ColumnSet = new ColumnSet(true), //or specify what fields you want from ccseq_contract
    LinkEntities =  {
        new LinkEntity() {              
            LinkFromEntityName = "ccseq_contract",
            LinkToEntityName = "ccseq_opportunity_ccseq_contract",
            ColumnSet = new ColumnSet(false), //don't fetch any fields from the link table
            LinkCriteria = new FilterExpression() {
                FilterOperator = LogicalOperator.And,
                Conditions = {
                    new ConditionExpression("opportunityid", ConditionOperator.Equal, wonOpportunity.Id)                    
                }
            }
        }
    }       
};

顺便说一句，当您不使用 'in' 查询运算符时，如果您生成了强类型实体类，我真的更喜欢使用 LINQ 查询而不是查询表达式。 LINQ 查询看起来像

using(var ctx = new OrganizationServiceContext(service)) {
    var contracts = (
        from c in ctx.CreateQuery<ccseq_contract>()
        join lnk in ctx.CreateQuery<ccseq_opportunity_ccseq_contract>() on c.ccseq_contractId equals link.ccseq_contractId
        where lnk.opportunityid = wonOpportunity.Id
        select c
        // Or, to fetch only some fields, do 
        // select new { c.ccseq_contractId, c.ccseq_name }
        ).ToList();
}

Answer 2

请尝试使用以下 XML 查询检索合同列表。查询是在 N:N 关系上完成的。

<fetch  mapping='logical'>
    <entity name='ccseq_opportunity_ccseq_contract'>
        <attribute name='opportunityid'/>
        <attribute name='ccseq_contractid'/>
        <link-entity name='opportunity' to='opportunityid' from='opportunityid' alias='opportunity'>
            <attribute name='opportunityid'/>
            <filter type='and'>
                <condition attribute='opportunityid' operator='eq' value=$'{wonOpportunity.Id}'/>
            </filter>
        </link-entity>
    </entity>
</fetch>

希望对您有所帮助。

Answer 3

这是我结束的地方。这部分基于 gnud 的回答。

QueryExpression query = new QueryExpression("ccseq_opportunity_ccseq_contract");
query.ColumnSet.AddColumns(Contract.Properties.ContractId, Opportunity.Properties.OpportunityId);
query.Criteria = new FilterExpression();
query.Criteria.AddCondition(Opportunity.Properties.OpportunityId, ConditionOperator.Equal, wonOpportunity.Id);

EntityCollection contracts = service.RetrieveMultiple(query);

Answer 4

另一个可以使查询逻辑在视觉上更易理解的答案。像sql中那样思考，先切换到中间table，然后切换到其他table

        QueryExpression query = new QueryExpression("ccseq_contract")
        {
            ColumnSet = new ColumnSet(true),
            LinkEntities =
            {
                new LinkEntity
                {
                    LinkFromEntityName = "ccseq_contract",
                    LinkToEntityName = "ccseq_opportunity_ccseq_contract",
                    LinkFromAttributeName = "ccseq_contractId",
                    LinkToAttributeName = "ccseq_contractId",
                    LinkEntities =
                    {
                        new LinkEntity
                        {
                            LinkFromEntityName = "ccseq_opportunity_ccseq_contract",
                            LinkToEntityName = "opportunity",
                            LinkFromAttributeName = "opportunityid",
                            LinkToAttributeName = "opportunityid",
                            LinkCriteria = new FilterExpression
                            {
                                Conditions =
                                {
                                    new ConditionExpression("opportunityid", ConditionOperator.Equal, wonOpportunity.Id)
                                }
                            }
                        }
                    }
                }
            }
        };

检索 N:N 关系 Dynamics CRM

Retrieve N:N relationship Dynamics CRM

c#

microsoft-dynamics

dynamics-crm