是否可以同时执行两个不同类型的 LINQ 查询？

Question

我有两种材料请求和安全用户模型：

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; }
}

我想根据用户名搜索材料请求，所以我制作了一个这样的材料请求视图模型：

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; }
}    

我从视图中获取用户名并创建一个 where 字符串，如“x=>x.UserName.Contains("Something")”，并将其作为 searchQuery 发送到我的材料请求搜索方法：

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 转换问题，ToPagedList() 方法无法执行查询。 这是一个正确的方法吗？

Answer 1

如果您将“SearchQuery”以字符串格式传递给 GetPagedRecords() 方法，您可以在“MaterialRequestMasterViewModel”视图模型的属性用户 id 的标题中添加一个属性，并使用安全用户模型的名称。

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; }
}    

然后使用反射来获取属性属性的值并将其添加到您的 where 子句中。 搜索查询值应该是这样的：

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

我认为它对你有用。

Answer 2

where 的参数必须是布尔函数，所以你应该这样发送它而不是字符串。

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);
}

你可以像这样创建函数变量

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

你可以像这样组合这种类型的多个函数

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

等等