C# Linq 在 Group By 中创建派生类列表

Question

我有一个方法，在该方法中我调用一个方法，该方法执行返回对象的 IEnumerable 的查询，然后我通过 Linq 对此 IEnumerable 执行分组，并详细说明分组的结果以将其插入到 JQGrid 中。在分组中，我创建了一个包含其他对象列表的对象。我希望这个列表不是基本类型，但我希望它是派生类型。 这是对执行查询的方法的调用，返回 IEnumerable 对象：

IEnumerable documentList = ObjBase.getAll(string.IsNullOrEmpty(columnList) ? null : columnList.Split(';'), sidx, sord, sqlWhere, out totalRows, userid: userId, siteId: siteId);

这是我在 Linq 分组后拥有的对象类别：

public class DocumentContact : ObjBase
{
    public long? CODE_CUSTOMER_ID { get; set; }
    public long? CODE_CUSTOMERTYPEID { get; set; }
    public long? CODE_CONTRACT_ID { get; set; }
    public long CODE_SITEID { get; set; }
    public string DESC_CONTACT_NUMBER { get; set; }
    public string DESC_CONTRACT_NUMBER { get; set; }
    public string DESC_CONTRACT_STATES { get; set; }
    public List<DocumentModelDates> Documents { get; set; }
}

这是 DocumentModel 类：

public class DocumentModel : ObjBase
{
    private long _id;
    private string _documentModel;
    private long? _documentModelTypeId;
    private long? _documentModelIssuingEntityId;
    private string _documentModelFilename;
    private string _documentModelPath;
    private DateTime? _documentModelStart;
    private DateTime? _documentModelEnd;
    private string _documentModelVersion;
    private long _contractId;
    private string _contractNumber;
    private long _contractTypeId;
    private long _contractStateId;
    private string _contractState;
    private long _documentModelStateId;
    private string _documentModelValoId;
    private DateTime? _documentModelUploadDate;
    private byte[] _documentModelContent;
    private long _documentModelFilter;
    private bool _flagDeleted;
    private long _userId;
    private int _orderDocumentModel = 0;
    private string _placeOfIssue;
    private string _issuingEntity;
    private DateTime? _releaseDate;
    private int? _idOpInsert;
    private int? _idOpId;
    private long? _customerId;
    private long? _customerTypeId;
    private string _customerNumber;
    private DateTime? _documentModelInvalidated;
    private bool _flagValidating;
    private string _fileRemotePath;
    private long? _folderId;
    private string _folderName;
    protected new HELPSI_Database HELPSI_Database = Common.HELPSI_Database.HELPSI_Anag;
}

这是 DocumentModelDates，派生自 DocumentModel：

    public class DocumentModelDates : DocumentModel
{
    public long? DateStart { get; set; }
    public long? DateEnd { get; set; }
    public long? DateUpload { get; set; }

    public DocumentModelDates(DocumentModel document)
    {
        this.CODE_DOCUMENT_MODEL_ID = document.CODE_DOCUMENT_MODEL_ID;
        this.DateStart = document.DATE_DOCUMENT_MODEL_START.Value.Ticks;
        this.DateEnd = document.DATE_DOCUMENT_MODEL_END.Value.Ticks;
        this.DateUpload = document.DATE_DOCUMENT_MODEL_UPLOAD.Value.Ticks;
    }
}

这是对这些 IEnumerable 的 Group By Linq 操作：

    var documentContact = documentList.GroupBy(c => new
    {
        c.CODE_CUSTOMERID,
        c.DESC_CONTACT_NUMBER,
        c.CODE_CUSTOMERTYPEID,
        c.CODE_CONTRACT_ID, 
        c.DESC_CONTRACT_NUMBER,
        c.DESC_CONTRACT_STATES,
    })
    .Select(gcs => new DocumentContact()
    {
        CODE_CUSTOMER_ID = gcs.Key.CODE_CUSTOMERID,
        DESC_CONTACT_NUMBER = gcs.Key.DESC_CONTACT_NUMBER,
        CODE_CUSTOMERTYPEID = gcs.Key.CODE_CUSTOMERTYPEID,
        CODE_CONTRACT_ID = gcs.Key.CODE_CONTRACT_ID,
        DESC_CONTRACT_NUMBER = gcs.Key.DESC_CONTRACT_NUMBER,
        DESC_CONTRACT_STATES = gcs.Key.DESC_CONTRACT_STATES,
        CODE_SITEID = siteId,
        Documents = gcs.ToList(),
    });

如果这样做，我会遇到转换错误：有没有办法在此 Select 中创建 DocumentModelDates 列表？谢谢。

Answer 1

你只需要：

.Select(gcs => new DocumentContact()
{
    //...
    Documents = gcs.Select(i => new DocumentModelDates(i)).ToList()
});

Answer 2

试试这样的

   public class DocumentModelDates
    {
        private DateTime _DateStart { get; set; }
        public long DateStart
        {
            get { return _DateStart.ToBinary(); }
            set { _DateStart = DateTime.FromBinary(value);}

        }
    }