从Elasticsearch中的索引中仅获取过滤的嵌套对象 [英] Fetch only filtered nested objects from index in elasticsearch

问题描述

我有一个包含嵌套对象的文档，如下所示：

I have a document with nested objects, something like this:

{
    "title" : "Title 1",
    "books": [{
        "book_title": "b title 1",
        "year": 2014
    }, {
        "book_title": "b title 2",
        "year": 2015
    }]
}

现在，我需要按书名（不是book_title）和年份（比如说2014）过滤书籍。我需要的输出将是：

Now I need to filter the books on by title (not book_title) and year (let's say 2014). The output I need will be:

{
    "title" : "Title 1",
    "books": [{
        "book_title": "b title 1",
        "year": 2014
    }]
}

当我使用嵌套过滤器时，即使它们不匹配，我也会得到所有嵌套对象。我如何只获取匹配的嵌套对象？

When I use a nested filter I get all the nested objects even if they don't match. How can I fetch only the matched nested objects?

推荐答案

您需要使用嵌套 inner_hits 功能如下。

You need to use the nested inner_hits feature like below.

{
  "_source": [
    "title"
  ],
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "title": "title 1"
          }
        },
        {
          "nested": {
            "path": "books",
            "query": {
              "term": {
                "books.year": 2014
              }
            },
            "inner_hits": {}
          }
        }
      ]
    }
  }
}

在输出中，您将准确获得所需的内容，即 title 字段和嵌套的 books 数组中的匹配图书。

In the output you'll get exactly what you expect, namely the title field and the matching book from the nested books array.

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