是否可以同時執行兩個不同型別的LINQ查詢？

我有兩種材料請求和安全用戶模型：

public class MaterialRequestMaster : BaseDomain<long>
{
  public string RequestCode { get; private set; }
  public string Description { get; private set; }
  public GlobalEnums.MaterialRequestStatus Status { get; set; }
  public int UserId { get; private set; }

  public SecurityUser User { get; private set; } 
}  

public class SecurityUser :IdentityUser<int>
{
  public string  Name { get; set; }
  public int  PersonelCodeId { get; set; }
  public ICollection<MaterialRequestMaster> MaterialRequestMaster { get; set; }
}

我想根據 User Name 對 Material Requests 進行搜索，所以我制作了一個 Material Request 的視圖模型，如下所示：

public class MaterialRequestMasterViewModel
{
  public long Id { get; set; }
  [Required(ErrorMessage = "Please Enter The Code")]
  public string RequestCode { get; set; }
  public GlobalEnums.MaterialRequestStatus Status{ get; set; }
  [MaxLength(255)]
  public string Description { get; set; }
  public int UserId { get; set; }
  public string UserName { get; set; }
  public bool IsDeleted { get; set; }
  public DateTime CreationDate { get; set; }
}    

我從視圖中獲取用戶名并創建一個像 "x=>x.UserName.Contains("Something")" 這樣的字串，并將其作為 searchQuery 發送到我的材料請求搜索方法：

public IPagedList<MaterialRequestMasterViewModel> GetPagedRecords(int pageNumber, int pageSize, string orderByCol, string order, string searchQuery)
{
IQueryable<MaterialRequestMaster> query;

query = query = _IMRMRepository.Get(); //Gets all records of <MaterialRecustMaster>

IQueryable<MaterialRequestMasterViewModel> searchedQuery;

searchedQuery = query.Select(n => new MaterialRequestMasterViewModel //Fill ViewModel 
 (
  n.Id,
  n.RequestCode,
  n.Status,
  n.Description,
  n.UserId,
  n.User.Name,
  n.CreationDate,
  n.IsDeleted
 ));

if (!string.IsNullOrWhiteSpace(searchQuery))
 searchedQuery = searchedQuery.Where(searchQuery);

return searchedQuery.ToPagedList(pageNumber, pageSize);
}

由于 LINQ 轉換問題，ToPagedList() 方法無法執行查詢。這是一個正確的方法嗎？

uj5u.com熱心網友回復：

如果您將“SearchQuery”作為字串格式傳遞給 GetPagedRecords() 方法，您可以在“MaterialRequestMaster”模型中的屬性用戶 id 的標頭中添加一個具有安全用戶模型名稱的屬性。

public class MaterialRequestMasterViewModel
{
  public long Id { get; set; }
  [Required(ErrorMessage = "Please Enter The Code")]
  public string RequestCode { get; set; }
  public GlobalEnums.MaterialRequestStatus Status{ get; set; }
  [MaxLength(255)]
  public string Description { get; set; }
  [RelationName="SecurityUser"]
  public int UserId { get; set; }
  public string UserName { get; set; }
  public bool IsDeleted { get; set; }
  public DateTime CreationDate { get; set; }
}    

然后使用反射來獲取 property 屬性的值并將其添加到您的 where 子句中。值應該是這樣的：

RelationPropertyValue = assembly.GetProperty("UserId").GetCustomAttribute<RelationName>();
searchQuery = $"x => x.{RelationPropertyValue}.Contains(\"Something\")"

我認為它對你有用。

uj5u.com熱心網友回復：

where 的引數必須是一個布爾函式，所以你應該像那樣發送它而不是字串。

public IPagedList<MaterialRequestMasterViewModel> GetPagedRecords(int pageNumber, int pageSize, string orderByCol, string order, Func<SecurityUser ,Boolean> searchQuery )
{
IQueryable<MaterialRequestMaster> query;

query = query = _IMRMRepository.Get(); //Gets all records of <MaterialRecustMaster>

IQueryable<MaterialRequestMasterViewModel> searchedQuery;

searchedQuery = query.Select(n => new MaterialRequestMasterViewModel //Fill ViewModel 
 (
  n.Id,
  n.RequestCode,
  n.Status,
  n.Description,
  n.UserId,
  n.User.Name,
  n.CreationDate,
  n.IsDeleted
 ));

if (searchQuery != null)
 searchedQuery = searchedQuery.Where(searchQuery);

return searchedQuery.ToPagedList(pageNumber, pageSize);
}

您可以像這樣創建函式變數

Func<SecurityUser, boolean> searchFunc = x => x.UserName.Contains("Something");

您可以像這樣組合這種型別的多個函式

Func<SecurityUser, boolean> combined = x=> searchFunc(x) || x.Id > 100;

等等。

標籤：C＃ 林克 asp.net核心 模型视图控制器 视图模型

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