c# – 列出IQueryable对象内部

发布时间：2020-12-15 17:25:08 所属栏目：百科来源：网络整理

导读：鉴于以下内容： public class Person{ public int ID { get; set;} public string Name { get; set;} public IQueryablePet Pets { get;set; }}public class Pet{ public int id { get; set; } public int OwnerId { get; set; } public string Name { get;

鉴于以下内容：

public class Person
{
  public int ID { get; set;}
  public string Name { get; set;}
  public IQueryable<Pet> Pets { get;set; }
}

public class Pet
{
  public int id { get; set; }
  public int OwnerId { get; set; }
  public string Name { get; set; }
}

public class SearchCriteria
{
  public string PersonName {get; set; }
  public List<string> PetNames {get; set;}
}

在使用IQueryable进行搜索时,用他们的宠物实现所有人的选择

public List<Person> GetWithPets(SearchCriteria search)
{
     var people = (from p in context.People
                   where p.Name == search.PersonName
                   select new Person{
                          ID = p.ID,Name = p.Name,Pets = (from pt in context.Pets
                                where pt.OwnerId == p.ID
                                select new Pet {
                                   id = pt.ID,OwnerId = pt.OwnerId,Name = pt.Name
                                }).AsQueryable
                   }).AsQueryable();

       foreach(var str in search.PetNames)
       {
            people = people.Where(o=>o.Pets.Any(p=>p.Name == str));
       }
  return people.ToList();
}

我的问题是,无论搜索名称的foreach,在返回的人员列表中,即使有,宠物也是null
与那个人相关的宠物,我哪里出错了？

编辑：

public class Person
{
    public int ID { get; set; }
    public string Name { get; set; }
    public IQueryable<Animal> Pets { get; set; }
}

public class Animal
{
    public int id { get; set; }
    public int? OwnerId { get; set; }
    public string Name { get; set; }
}

public class SearchCriteria
{
    public string PersonName { get; set; }
    public List<string> PetNames { get; set; }
}



class Program
{
    public static List<Person> GetWithPets(SearchCriteria search)
    {
        using (DatabaseEntities context = new DatabaseEntities())
        {
            var people = (from p in context.Peoples
                          where p.Name == search.PersonName
                          select new Person
                          {
                              ID = p.ID,Pets = (from pt in context.Pets
                                      where pt.OwnerID == p.ID
                                      select new Animal
                                      {
                                          id = pt.ID,OwnerId = pt.OwnerID,Name = pt.Name
                                      }).AsQueryable()
                          }).AsQueryable();

            foreach (var str in search.PetNames)
            {
                people = people.Where(o => o.Pets.Any(p => p.Name == str));
            }
            return people.ToList();
        }
    }

解决方法

如果Person和Pet是您模型的实体,并且Person.Pets是Pet实体的导航属性,并且您希望拥有包含所有完整Pet实体的完整Person实体并引用您的注释…

my method is supposed to return a list of people that have name equals
search.PersonName & ALL their pets but only those people who own the
pets with those names in the search.PetNames

……你可以用这个：

public List<Person> GetWithPets(SearchCriteria search)
{
    var people = from p in context.People.Include("Pets")
                 where p.Name == search.PersonName
                    && p.Pets.Any(pt => search.PetNames.Contains(pt.Name))
                 select p;

    return people.ToList();
}

（编辑：李大同）

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