我试图使用NEST返回从公共子类派生的各种对象。
在这个例子中,我有一个名为" Person"然后我派出了名为" Firefighter"和#34;老师"。实例存储在名为" people"。
的索引中我想搜索我的索引并返回一群消防员和教师,但我能找到的最好的是人员列表。
The documentation要求使用ISearchResponse.Types,但我没有看到此函数存在。 This post,在StackOverflow上,也引用.Types函数,但我不认为它是一个选项。
以下是我试图解决的问题的一个例子。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Nest;
using Elasticsearch;
using Elasticsearch.Net;
namespace ElasticSearchTest
{
class Program
{
static void Main(string[] args)
{
var myTeacher = new Teacher { id="1", firstName = "Steve", lastName = "TheTeacher", gradeNumber = 8 };
var myFiregighter = new Firefighter { id="2", firstName = "Frank", lastName = "TheFirefighter", helmetSize = 12 };
SingleNodeConnectionPool esPool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
ConnectionSettings esSettings = new ConnectionSettings(esPool);
esSettings.DefaultIndex("people");
Nest.ElasticClient esClient = new ElasticClient(esSettings);
esClient.DeleteIndex("people");
esClient.Index<Teacher>(myTeacher);
esClient.Index<Firefighter>(myFiregighter);
System.Threading.Thread.Sleep(2000);
ISearchResponse<Person> response = esClient.Search<Person>(s => s
.AllTypes()
.MatchAll()
);
foreach (Person person in response.Documents)
Console.WriteLine(person);
}
public class Person
{
public string id { get; set; }
public string firstName { get; set; }
public string lastName { get; set; }
public override string ToString() { return String.Format("{0}, {1}", lastName, firstName);}
}
public class Firefighter : Person
{
public int helmetSize { get; set; }
}
public class Teacher : Person {
public int gradeNumber { get; set; }
}
}
}
数据似乎在Elasticsearch内正确构建:
{
took: 1,
timed_out: false,
_shards: {
total: 5,
successful: 5,
failed: 0
},
hits: {
total: 2,
max_score: 1,
hits: [{
_index: "people",
_type: "firefighter",
_id: "2",
_score: 1,
_source: {
helmetSize: 12,
id: "2",
firstName: "Frank",
lastName: "TheFirefighter"
}
}, {
_index: "people",
_type: "teacher",
_id: "1",
_score: 1,
_source: {
gradeNumber: 8,
id: "1",
firstName: "Steve",
lastName: "TheTeacher"
}
}]
}
}
如何让NEST返回从基类派生的混合实例列表?
非常感谢!
-Z
答案 0 :(得分:3)
NEST supports Covariant results,在NEST 2.x中,ISearchResponse<T>
上方法的命名已更改为.Type()
,以便在发出请求时与URI中表示的路由参数对齐到Elasticsearch(.Type()
可以是一种或多种类型)。
NEST 2.x的协变结果的一个例子是
static void Main(string[] args)
{
var myTeacher = new Teacher { id = "1", firstName = "Steve", lastName = "TheTeacher", gradeNumber = 8 };
var myFiregighter = new Firefighter { id = "2", firstName = "Frank", lastName = "TheFirefighter", helmetSize = 12 };
SingleNodeConnectionPool esPool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
ConnectionSettings esSettings = new ConnectionSettings(esPool);
esSettings.DefaultIndex("people");
Nest.ElasticClient esClient = new ElasticClient(esSettings);
if (esClient.IndexExists("people").Exists)
{
esClient.DeleteIndex("people");
}
esClient.Index<Teacher>(myTeacher, i => i.Refresh());
esClient.Index<Firefighter>(myFiregighter, i => i.Refresh());
// perform the search using the base type i.e. Person
ISearchResponse<Person> response = esClient.Search<Person>(s => s
// Use .Type to specify the derived types that we expect to return
.Type(Types.Type(typeof(Teacher), typeof(Firefighter)))
.MatchAll()
);
foreach (Person person in response.Documents)
Console.WriteLine(person);
}
public class Person
{
public string id { get; set; }
public string firstName { get; set; }
public string lastName { get; set; }
public override string ToString() { return String.Format("{0}, {1}", lastName, firstName); }
}
public class Firefighter : Person
{
public int helmetSize { get; set; }
}
public class Teacher : Person
{
public int gradeNumber { get; set; }
}