c# - 使用 linq 规范化对象

Question

我有一个 IEnumerable<RuleSelection>具有这些属性:

public class RuleSelection{
  public int RuleId { get; set;}
  public int? CriteriaId { get; set; }
  public int? CriteriaSourceId{ get; set; }
}

RuleId在RuleSelection不是唯一的。

我可以编写一个 linq 查询来将这些规范化为 IEnumerable<Rule> 吗？这将是:

public class Rule{
  public int RuleId { get; set; }
  public IEnumerable<int> Criteria { get; set; }
  public IEnumerable<int> CriteriaSource { get; set; }
}

Rule.RuleId将是独一无二的，属性 Criteria和 CriteriaSource将包括所有 CriteriaId的和CriteriaSourceId用于 RuleId分别。

Answer 1

听起来你想要这样的东西:

var rules = selections.GroupBy(rs => rs.RuleId)
                      .Select(g => new Rule {
                                  RuleId = g.Key,
                                  Criteria = g.Select(rs => rs.CriteriaId)
                                              .Where(c => c != null)
                                              .Select(c => c.Value)
                                              .ToList(),
                                  CriteriaSource = g.Select(rs => rs.CriteriaSourceId)
                                                    .Where(c => c != null)
                                                    .Select(c => c.Value)
                                                    .ToList(),
                              });