Linq通过搜索关键字从对象的关系列表中选择对象

Question

I want to get the Principal of School using a search keyword. Schools can have list of users from which one is of a principal role.

Now my problem is I am implementing an auto search that takes a keyword and searches on the basis for School Name, Code, and principal name.

代码：

 public class School : AuditableDataEntity<int>
    {
        [Required]
        [MaxLength(200)]
        public string Name { get; set; }

        [MaxLength(150)]
        public string Code { get; set; }

        public District District { get; set; }

        public ICollection<UserProfile> Users { get; set; }


    }

public class UserProfile : AuditableDataEntity<Guid>
    {

        [Required]
        [MaxLength(100)]
        public string FirstName { get; set; }

        [Required]
        [MaxLength(100)]
        public string LastName { get; set; }

        [Required]
        [MaxLength(200)]
        public string Email { get; set; }

        [MaxLength(50)]
        public string PhoneWork { get; set; }

        [MaxLength(20)]
        public int PhoneWorkExt { get; set; }

        [MaxLength(50)]
        public string PhoneMobile { get; set; }       

        public UserLevel UserLevel { get; set; }

        public UserRole UserRole { get; set; }

        public UserDesignation UserDesignation { get; set; }

        public School School { get; set; }
        public int? SchoolId { get; set; }

        public string FullName => $"{FirstName} {LastName}";
    }

Task<Response<IEnumerable<SchooSearchDTO>>> ISchoolQueryService.GetSchoolAutoCompleteData(string searchKeyword)
        {
            return _schoolQueryRepository.WithRelatedEntities().Where(x => x.Name.Contains(searchKeyword)
            ||x.Code.Contains(searchKeyword)
            || x.Users.FirstOrDefault(y => y.DataEntityState == DataEntityState.Published && y.UserDesignation == UserDesignation.Principal).FullName.Contains(searchKeyword)).OrderBy(u => u.Name).Select(z => new SchooSearchDTO
            {
                PrincipalName = z.Name,
                CDSCode = z.Code

            }).ToResponseListAsync();
        }

错误：

The LINQ expression 'DbSet .Where(s => s.Name.Contains(__searchKeyword_0) || s.CDSCode.Contains(__searchKeyword_0) || DbSet .Where(u => EF.Property>(s, "Id") != null && EF.Property>(s, "Id") == EF.Property>(u, "SchoolId")) .Where(u => (int)u.DataEntityState == 1 && (int)u.UserDesignation == 1) .Select(u => u.FullName) .FirstOrDefault().Contains(__searchKeyword_0))' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync(). See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.

Answer 1

问题在于 EF 无法将其转换为 SQL。

x.Users.FirstOrDefault(y => y.DataEntityState == DataEntityState.Published && y.UserDesignation == UserDesignation.Principal).FullName.Contains(searchKeyword)

因此尝试使用 Any 而不是在 LINQ 中使用 FirstOrDefault 选择用户，以便 EF 能够将其转换为 SQL.

Task<Response<IEnumerable<SchooSearchDTO>>> ISchoolQueryService.GetSchoolAutoCompleteData(string searchKeyword)
{
    return _schoolQueryRepository.WithRelatedEntities().Where(x => x.Name.Contains(searchKeyword)
        ||x.Code.Contains(searchKeyword)
        || x.Users.Any(y => y.DataEntityState == DataEntityState.Published && y.UserDesignation == UserDesignation.Principal && y.FirstName.Contains(searchKeyword))
    ).OrderBy(u => u.Name).Select(z => new SchooSearchDTO
    {
        PrincipalName = z.Name,
        CDSCode = z.Code

    }).ToResponseListAsync();
}

参见：The LINQ expression could not be translated and will be evaluated locally

编辑：

您还需要使用 FirstName 因为 FullName 是 属性 而您在 SQL.

中没有