使用 NEST(ElasticSearch) 搜索嵌套数组答案

【问题标题】：Search on nested array using NEST(ElasticSearch)使用 NEST(ElasticSearch) 搜索嵌套数组
【发布时间】：2020-07-21 12:15:53
【问题描述】：

我想使用 Nest 过滤嵌套数组中的数据。鉴于我有以下课程：

public class Package
{
    public IEnumerable<PackageItem> PackageItems { get; set; }
}

public class PackageItem
{
    public string Title { get; set; }
    public decimal Price { get; set; }
}

我已经使用 NEST 在 ElasticSearch 中索引了这些数据：这是我的数据：

"hits" : [
  {
    "_index" : "packages",
    "_type" : "_doc",
    "_id" : "cf08b05c-c8b5-45cb-bca8-17267c3613fb",
    "_score" : 1.0,
    "_source" : {
      "id" : "cf08b05c-c8b5-45cb-bca8-17267c3613fb",
      "PackageItems" : [
        {
          "Title" : "some-title",
          "price" : 100000.0
        },
        {
          "Title" : "some-title",
          "price" : 200000.0
        }
      ]
    }
  },
  {
    "_index" : "packages",
    "_type" : "_doc",
    "_id" : "39436cb3-483e-4fb4-92e4-4e06ecad27a1",
    "_score" : 1.0,
    "_source" : {
      "id" : "39436cb3-483e-4fb4-92e4-4e06ecad27a1",
      "PackageItems" : [
        {
          "Title" : "some-title",
          "price" : 100000.0
        },
        {
          "Title" : "some-title",
          "price" : 400000.0
        }
      ]
    }
  },
  {
    "_index" : "packages",
    "_type" : "_doc",
    "_id" : "cd5d3587-838b-46ec-babc-d756c5587396",
    "_score" : 1.0,
    "_source" : {
      "id" : "cd5d3587-838b-46ec-babc-d756c5587396",
      "PackageItems" : [
        {
          "Title" : "some-title",
          "price" : 300000.0
        },
        {
          "Title" : "some-title",
          "price" : 500000.0
        }
      ]
    }
  }
]

我想过滤具有 minimumPackageItemPrice:100000 和 maximumPackageItemPrice:400000 的包裹。我应该使用 NEST 执行什么查询？

结果应该是这样的：

"hits" : [
  {
    "_index" : "packages",
    "_type" : "_doc",
    "_id" : "cf08b05c-c8b5-45cb-bca8-17267c3613fb",
    "_score" : 1.0,
    "_source" : {
      "id" : "cf08b05c-c8b5-45cb-bca8-17267c3613fb",
      "PackageItems" : [
        {
          "Title" : "some-title",
          "price" : 100000.0
        },
        {
          "Title" : "some-title",
          "price" : 200000.0
        }
      ]
    }
  },
  {
    "_index" : "inventories",
    "_type" : "_doc",
    "_id" : "39436cb3-483e-4fb4-92e4-4e06ecad27a1",
    "_score" : 1.0,
    "_source" : {
      "id" : "39436cb3-483e-4fb4-92e4-4e06ecad27a1",
      "PackageItems" : [
        {
          "Title" : "some-title",
          "price" : 100000.0
        },
        {
          "Title" : "some-title",
          "price" : 400000.0
        }
      ]
    }
  }
]

【问题讨论】：

PackageItems 是映射中的嵌套字段吗？
是的，它是嵌套的

标签： c# elasticsearch nest

【解决方案1】：

要通过NEST 在 Elasticsearch 上触发范围查询，您可以使用范围查询。方法是您可以为您的场景构建一个范围查询，并通过NEST 客户端的搜索方法触发该查询。

为您的案例生成范围查询

// This method builds the range query where price should be between 
// 100000.0 and 400000.0 (inclusive range in this case)
private static QueryContainer BuildNestedRangeQuery()
{
    return new QueryContainerDescriptor<Package>()
        .Nested(n =>
            n.Path(p => p.PackageItems)
             .Query(q => q
                .Range(r => r
                    .Field(f => f.PackageItems.FirstOrDefault().Price)
                    .GreaterThanOrEquals(100000.0)
                    .LessThanOrEquals(400000.0))
                )
             )
        )
}

触发搜索

可以通过NEST 客户端触发搜索，如下所示。这可能会根据您自己的实现而有所不同。但是，上面的范围查询保持不变。

// Replace T with type of your choice and client is NEST client
var result = client.Search<T>(    
    .From(0)
    .Size(20)
    .Query(q => BuildNestedRangeQuery())
    // other methods that you want to chain go here
)

【讨论】：