我有这个 linq 查询： 私有异步任务

Question

如您所见，我使用

FirstOrDefault()

 从分组数据中检索第一个元素，确保高效的数据检索，而无需进行不必要的枚举。

但是我需要归还它

AsQueryable()

因为在另一种方法中我有：

public async Task<PagedResultDto<ClaimSummaryDto>> GetListAsync(GetClaimListDto input)
{
    var claimTransactionSetBatch = await this.GetClaimList(input);

   var claims = claimTransactionSetBatch.Select(x => new ClaimSummaryDto()
   {
    AgencyIdentifier = x.Claim.AgencyIdentifier,
    ....
   }

claims = claims.OrderBy(string.IsNullOrWhiteSpace(input.Sorting) ? "DateOfServiceStart" : input.Sorting).PageBy(input);

   return new PagedResultDto<ClaimSummaryDto>(total, claims.ToList());
}

因此，返回一个 IQueryable，如果我将其作为列表返回，则代码：

claims.OrderBy(string.IsNullOrWhiteSpace(input.Sorting) ? "DateOfServiceStart" : input.Sorting).PageBy(input);

抛出错误，因为它需要是

IQueryable

 才能执行排序：

严重性代码描述项目文件行抑制状态
错误 CS1929“IEnumerable”不包含
“OrderBy”的定义和最佳扩展方法重载
'DynamicQueryableExtensions.OrderBy(IQueryable, 字符串, 参数
object?[])' 需要类型为 'System.Linq.IQueryable' 的接收器

所以，我担心这个查询的性能问题，因为我们在使用

.ToList()

时具体化了查询，然后再次将其移至AsQueryable，在使用的方法中，我们再次将其转换为列表，如何才能我改进这段代码？另外，如果我不像这样应用 GetClaimList 方法中的

.ToList()

：

...

              {
                  Batch = grouped.Select(x => x.claimBatch).FirstOrDefault(),
                  TransactionSet = grouped.Select(x => x.transactionSet).FirstOrDefault(),
                  Claim = grouped.Select(x => x.claim).FirstOrDefault()
              });


return claims;

当它试图最后实现查询时，它会抛出一个大错误：

return new PagedResultDto<ClaimSummaryDto>(total, claims.ToList());

错误：

LINQ 表达式 'DbSet() .Where(c => __ef_filter__p_0 || (Guid?)EF.Property(c, "TenantId") == __ef_filter__CurrentTenantId_1) .SelectMany( 集合选择器：c => DbSet() .Where(c0 => EF.Property

(c, "Id") != null && object.Equals( objA: (对象)EF.Property

(c, "Id"), objB: (对象)EF.Property

(c0, "ClaimBatchId"))) .DefaultIfEmpty(), 结果选择器：（c，c）=>新的透明标识符

（ 外层 = c, 内=c ）） .SelectMany( 集合选择器： ti => DbSet() .Where(c1 => EF.Property(ti.Inner, "Id") != null && object.Equals( objA: (对象)EF.Property(ti.Inner, "Id"), objB: (对象)EF.Property(c1, "TransactionSetId"))) .DefaultIfEmpty(), 结果选择器：（ti，c）=>新的透明标识符，ClaimTransactionSetClaim>（ 外=ti, 内=c ）） 。加入（ 内部：DbSet() .Where(c2 => __ef_filter__p_0 || (Guid?)EF.Property(c2, "TenantId") == __ef_filter__CurrentTenantId_1), 外键选择器: ti0 => (对象)ti0.Inner.ClaimId, innerKeySelector: c2 => (object)c2.Id, 结果选择器：（ti0，c2）=>新的透明标识符，ClaimTransactionSetClaim>，Claim>（ 外层 = ti0, 内=c2 ）） .Where(ti1 => ti1.Outer.Outer.Outer.SourceClaimBatchId == null && True && True && False || __input_Status_1 .包含(ti1.Inner.Status) && True && True && True && True) .OrderByDescending(ti1 => ti1.Outer.Outer.Outer.Id) .GroupBy(ti1 => ti1.Inner.Id) .Select(g => 新的 ClaimTransactionSetBatch{ 批次 = g .AsQueryable() .Select(e0 => e0.Outer.Outer.Outer) .FirstOrDefault(), 交易集 = g .AsQueryable() .Select(e0 => e0.Outer.Outer.Inner) .FirstOrDefault(), 索赔= g .AsQueryable() .Select(e0 => 包含表达式( 实体表达式： 包含表达式( 实体表达式： 包含表达式( 实体表达式： 包含表达式( 实体表达式： e0.内部， 导航表达式： MaterializeCollectionNavigation( 导航：Claim.ServiceLines， 子查询：DbSet() .Where(c3 => EF.Property(e0.Inner, "Id") != null && object.Equals( objA: (对象)EF.Property(e0.Inner, "Id"), objB: (对象)EF.Property(c3, "ClaimId")))), ServiceLines) , 导航表达式： MaterializeCollectionNavigation( 导航：Claim.CustomProperties， 子查询：DbSet() .Where(c4 => EF.Property(e0.Inner, "Id") != null && object.Equals( objA: (对象)EF.Property(e0.Inner, "Id"), objB：（对象）EF.Property（c4，“ClaimId”）））），CustomProperties） , 导航表达式： MaterializeCollectionNavigation( 导航：Claim.TransactionSets， 子查询：DbSet() .Where(c5 => EF.Property(e0.Inner, "Id") != null && object.Equals( objA: (对象)EF.Property(e0.Inner, "Id"), objB：（对象）EF.Property（c5，“ClaimId”）））），TransactionSets） , 导航表达式： MaterializeCollectionNavigation( 导航：Claim.EventHistory， 子查询：DbSet() .Where(c6 => __ef_filter__p_0 || (Guid?)EF.Property(c6, "TenantId") == __ef_filter__CurrentTenantId_1) .Where(c6 => EF.Property(e0.Inner, "Id") != null && object.Equals( objA: (对象)EF.Property(e0.Inner, "Id"), objB：（对象）EF.Property（c6，“ClaimId”）））），EventHistory） ） .FirstOrDefault() } ） .OrderBy(e1 => e1.Claim.ServiceLines .Select(x => x.DateOfServiceStart) .Where(日期 => 日期.HasValue) .Min())' 无法翻译。要么以可翻译的形式重写查询，要么切换到客户端评估 通过插入对 'AsEnumerable'、'AsAsyncEnumerable' 的调用显式地 “ToList”或“ToListAsync”。看 https://go.microsoft.com/fwlink/?linkid=2101038了解更多信息。 我认为这是因为需要首先具体化firstOrDefault()（这就是我使用.ToList()的原因）

课程：

ClaimTransactionSetBatch

internal class ClaimTransactionSetBatch
{
    public Claim Claim { get; set; }
    public ClaimTransactionSet TransactionSet { get; set; }
    public ClaimBatch Batch { get; set; }
}

索赔：

public class Claim : AuditedAggregateRoot<Guid>, IMultiTenant, IProcessibleType {
    private IList<ClaimEvent> _eventHistory;
    public IList<ClaimEvent> EventHistory { get => this._eventHistory.OrderByDescending(e => e.TimeStamp).ToList(); set => _eventHistory = value; }
    private string _claimTypeCode;
    private decimal? _netPaidAmount;
    private ClaimPaymentStatus _paymentStatus;
    private ClaimVisitMatchStatus _visitMatchStatus;
    private ClaimStatus _status;
    private IList<ClaimAction> _claimActions;
    public IList<ClaimAction> AvailableActions { get { ... } }
    public Guid? TenantId { get; set; }
    public string SubmitterIdentifier { get; set; }
    public string ReceiverIdentifier { get; set; }
    public ClaimPaymentStatus PaymentStatus { get => this._paymentStatus; set { ... } }
    public string ClaimIdentifier { get; set; }
    public string BatchIdentifier { get; set; }
    // Include the rest of the properties here
    public string ClientGender { get; set; }
    public string ClientDiagnosisCode { get; set; }
    public Decimal NetAmount { get; set; }
    public string ClaimTypeCode { get => this._claimTypeCode; set { ... } }
    public ClaimType ClaimType { get; private set; }
    public string FacilityTypeCode { get; set; }
    public ClaimProcessingStatus ProcessingStatus { get; set; }
    public string ProcessingResultMessage { get; set; }
    public ClaimStatus Status { get => this._status; set { ... } }
    public Guid? ProcessingRulesetId { get; set; }
    public ClaimVisitMatchStatus VisitMatchStatus { get => this._visitMatchStatus; set { ... } }
    public decimal? NetPaidAmount { get => this._netPaidAmount; set { ... } }
    public DateTime? LastPaymentReceivedDate { get; set; }
    public string CostCenterIdentifier { get; set; }
    public string CostCenterCode { get; set; }
    public IList<ClaimServiceLine> ServiceLines { get; set; }
    public IList<ClaimCustomProperty> CustomProperties { get; set; }
    public IEnumerable<ClaimTransactionSetClaim> TransactionSets { get; private set; }
    public ClaimRulesetEntityType ClaimRulesetEntityType => ClaimRulesetEntityType.Claim;
    
    public Claim() {
        this.ServiceLines = new List<ClaimServiceLine>();
        this.CustomProperties = new List<ClaimCustomProperty>();
        this.EventHistory = new List<ClaimEvent>();
        this._eventHistory = new List<ClaimEvent>();
        this._claimActions = new List<ClaimAction>();
        this._paymentStatus = ClaimPaymentStatus.PaymentPending;
        this._status = ClaimStatus.InProcess;
    }

    public Claim(Guid id) : base(id) {
        this.ServiceLines = new List<ClaimServiceLine>();
        this.CustomProperties = new List<ClaimCustomProperty>();
        this.EventHistory = new List<ClaimEvent>();
        this._eventHistory = new List<ClaimEvent>();
        this._claimActions = new List<ClaimAction>();
        this._paymentStatus = ClaimPaymentStatus.PaymentPending;
        this._status = ClaimStatus.InProcess;
    }

    public Claim(Guid id, Guid claimTransactionSetId) : this(id) {
        //ClaimTransactionSetId = claimTransactionSetId;
    }
}

索赔交易集

       public class ClaimTransactionSet : Entity<Guid>
{
    private IList<ClaimTransactionSetClaim> claims = new List<ClaimTransactionSetClaim>();

    private DateTime? transmissionStatusChangedDate;
    private TransmissionStatus transmissionStatus;

    public Guid ClaimBatchId { get; set; }
    public Guid? SourceClaimTransactionSetId { get; set; }

    public IEnumerable<ClaimTransactionSetClaim> Claims => this.claims;

    public string GroupControlNumber { get; set; }
    public string GroupSenderCode { get; set; }
    public string GroupReceiverCode { get; set; }
    public string TransactionSetControlNumber { get; set; }

    public TransmissionStatus TransmissionStatus { get => this.transmissionStatus; set { if (this.transmissionStatus != value) { this.transmissionStatus = value; this.transmissionStatusChangedDate = DateTime.UtcNow; } } }

    public DateTime? TransmissionStatusChangedDate => this.transmissionStatusChangedDate;
}

索赔批次：

  public class ClaimBatch : AuditedAggregateRoot<Guid>, IMultiTenant, IProcessibleType
{
    public Guid? TenantId { get; set; }
    public Guid? SourceClaimBatchId { get; set; }
    public string InterchangeControlNumber { get; set; }
    public string BatchIdentifier { get; set; }
    public DateTime? BatchDate { get; set; }
    public string SenderIdentifier { get; set; }
    public string ReceiverIdentifier { get; set; }
    public string AgencyIdentifier { get; set; }
    public DateTime ReceivedDate { get; set; }
    public string Filename { get; set; }
    public ClaimBatchProcessingMethod ProcessingMethod { get; set; }

    public ClaimProcessingStatus ProcessingStatus { get; set; }
    public string ProcessingResultMessage { get; set; }
    public Guid? ProcessingRulesetId { get; set; }

    public IList<ClaimTransactionSet> TransactionSets { get; set; }

    public IList<ClaimBatchEvent> EventHistory { get; set; }
}

这个查询应该是transletabke。最好根据您的需求更正

OrderBy

Answer 1

var claimBatchQry = ... // initialize as IQueryable created from DbSet

var claims = 
    from claimBatch in claimBatchQry
    from transactionSet in claimBatch.TransactionSets
        .OrderBy(x => x.Id)
        .Take(1)
        .DefaultIfEmpty()
    from transactionSetClaim in transactionSet.Claims
        .OrderBy(x => x.Id)
        .Take(1)
        .DefaultIfEmpty()
    where ...
    orderby claimBatch.Id descending
    select new ClaimTransactionSetBatch
    {
        Batch = claimBatch,
        TransactionSet = transactionSet,
        Claim = transactionSetClaim.Claim // or just transactionSetClaim
    };