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Accepted
Danila
Asked:2023-04-08 03:49:34 +0000 UTC2023-04-08 03:49:34 +0000 UTC

更简洁的linq解决方案

  • 772

如何在 Linq 上用一个简洁的表达式替换以下行：

foreach (Company company in companies)
            {
                List<CheckPoint> checkPoints = await _context.CheckPoints
                    .Where(cp => cp.CompanyId == company.Id).ToListAsync();
            }

楷模：

public class CheckPoint
{
    [Key]
    public ulong Id { get; private set; }

    [Column("Name", TypeName = "nvarchar(MAX)")]
    public string Name { get; private set; }

    [Column("CompanyId", TypeName = "decimal(20, 0)")]
    public ulong CompanyId { get; private set; }

    public Company? Company { get; private set; }

    public CheckPoint(string name)
    {
        Name = name;
        CompanyId = default;
        Company = default;
    }
public class Company
{
    [Key]
    public ulong Id { get; private set; }

    [Column("FullName", TypeName = "nvarchar(MAX)")]
    public string FullName { get; private set; }

    public List<User>? Users { get; private set; }

    public List<CheckPoint>? CheckPoints { get; private set; }

    public Company(string fullName)
    {
        Id = default;
        FullName = fullName;
        Users = new List<User>();
        CheckPoints = new List<CheckPoint>();
    }
}
c#

1 个回答

  1. Best Answer
    List<CheckPoint> checkPoints = await _context.CheckPoints
    .Where(cp => companies.Select(c => c.Id).Contains(cp.CompanyId))
    .ToListAsync();

    或者

    List<CheckPoint> checkPoints = await _context.CheckPoints
    .Where(cp => companies.Any(c => c.Id == cp.CompanyId))
    .ToListAsync();

    我不知道哪个会更快。

    • 1

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