LINQ to Entities无法识别方法’System.Collections.Generic.Dictionary`2 ToDictionary

我正在尝试从DB中检索EmployeeDTO列表，这些列表存储在Employee表中。 每个员工都可以拥有一个或多个专业。 专业存储在OrganizationSpecialtyType中。 Employee和OrganizationSpecialtyType通过EmployeeSpecialty表与“多对多”相关联。

我使用以下查询并获得标题中的exception：

var q = _context.Employee.Where(p => employeeEMIIDs.Contains(p.EmployeeID)) .Select(p => new EmployeeDTO { EmployeeID = p.EmployeeID, GenderTypeID = p.GenderTypeID, FirstName = p.FirstName, LastName = p.LastName, Name = p.Name, MiddleName = p.MiddleName, DOB = p.DOB, Suffix = p.Suffix, Title = p.Title, Sepcialty = p.EmployeeSpecialty .ToDictionary(d => d.OrganizationSpecialtyType.SpecialtyTypeID, d => d.OrganizationSpecialtyType.Name) } ); 

在EmployeeDTO类属性中，特性是类型公共字典。

如果我执行此查询，一切都正常：

  var spec = _context.Employee.Where(p => p.EmployeeID == -9070).FirstOrDefault().EmployeeSpecialty.ToDictionary(d => d.OrganizationSpecialtyType.SpecialtyTypeID, d => d.OrganizationSpecialtyType.Name); 

如何解决我的第一个查询以获得具有专业的EmployeeDTO？

谢谢

Answer 1

您可以先选择匿名类型，然后再设置字典。

 var q = _context.Employee.Where(p => employeeEMIIDs.Contains(p.EmployeeID)) .Select(p => new { Employee = new EmployeeDTO { EmployeeID = p.EmployeeID, GenderTypeID = p.GenderTypeID, FirstName = p.FirstName, LastName = p.LastName, Name = p.Name, MiddleName = p.MiddleName, DOB = p.DOB, Suffix = p.Suffix, Title = p.Title }, Specialty = p.EmployeeSpecialty .Select(d => new { d.OrganizationSpecialtyType.SpecialtyTypeID, d.OrganizationSpecialtyType.Name }) }) .AsEnumerable() .Select(a => { a.Employee.Specialty = a.Specialty .ToDictionary(d => d.SpecialtyTypeID, d => d.Name); return a.Employee; });