根据关系集合计数过滤 FetchEntityCollection

Question

我目前获取这样的作业集合：

jobs = new EntityCollection<JobEntity>(new JobEntityFactory()); 

var bucket = GetJobsBucket(filter);

var tempContext = new Context();
tempContext.Add(jobs);
var sorter = new SortExpression(JobFields.Id | SortOperator.Descending);

adapter.FetchEntityCollection(jobs, bucket, maxCount, sorter, JobListPrefetchPath(false));

filter.TotalMatchesCount = adapter.GetDbCount(new JobEntityFactory().CreateFields(), bucket, null, false);
filter.ReturnedMatchesCount = jobs.Count;

tempContext.Clear();

return jobs;

其中存储桶包含大量谓词，例如

    bucket.Relations.Add(JobEntity.Relations.JobTypeEntityUsingJobTypeFk);
    bucket.Relations.Add(JobTypeEntity.Relations.JobTypeCategoryEntityUsingCategoryFk);   
    var fieldCompareValuePredicate = new FieldCompareValuePredicate(JobTypeCategoryFields.Filter, null,
                    ComparisonOperator.Equal, filter.JobCategory) { CaseSensitiveCollation = true };                        
    bucket.PredicateExpression.Add(fieldCompareValuePredicate);

作业实体有一组附件（通过外键）

如何过滤作业列表以仅选择带有一个或多个附件的作业？ 我知道我可以通过动态视图使用内存过滤器（AggregateSetPredicate），但这意味着我必须获取所有作业才能获得正确的计数，当前获取的返回计数有最大值。

Answer 1

解决方案是这样做：

    bucket.Relations.Add(JobEntity.Relations.AttachmentEntityUsingJobFk);
FieldCompareSetPredicate filteredAttachments;
filteredAttachments = new FieldCompareSetPredicate(JobFields.Id, null,
                                                   AttachmentFields.JobFk, null,
                                                   SetOperator.In, null);
 bucket.PredicateExpression.Add(filteredAttachments);