Question

我正在尝试编写一个动态搜索I和链接where子句我下面的类和示例代码。

public class Person
{
    public int PersonId { get; set; }
    //More Fields ..
}

//Link Table
public class PersonAddress
{
    public int PersonID { get; set; }
    public int AddressID { get; set; }
    //More Fields ..
}

public class Address
{
    public int AddressId { get; set; }
    public int ReferenceDataID { get; set; }
    //More Fields ..
}

public class ReferenceData
{
    public int ReferenceDataId { get; set; }
    public string MyData { get; set; }
    //More Fields ..
}


var query = (from p in People.Include("PersonAddresses")
 .Include("PersonAddresses.Address")
 .Include("PersonAddresses.Address.ReferenceData")
             select p);


if (!String.IsNullOrEmpty(searchName))
      query = query.Where(q => q.Search.Contains(person.SearchName));

// How can I access the MyData
if (!String.IsNullOrEmpty(searchCountry))
                query = query.Where(q => q.Search.Where(a => a. == "Ireland");

感谢。

Answer 1

如果要过滤相关记录，则在使用包含时无法进行过滤。 Include仅允许加载所有属性。在单个查询中获取过滤导航属性的唯一可能方法是手动查询，投影到非实体或匿名类型：

var query = from p in context.Persons
            select new 
            {
                Person = p,
                Addresses = p.PersonAddreeses
                             .Where(pa => pa.Address.Country == "Ireland")
            };

如果您想在不过滤加载地址的情况下从爱尔兰获取包含地址的人，则无法使用您定义的查询。期望表达式导致bool不是另一个查询。试试这个：

query = query.Where(p => p.PersonAddresses
                          .Any(pa => pa.Address.Country == "Ireland");

我绝对不确定你的例子中Search是什么。

LINQ Chaining Where子句

1 个答案: