在弹性搜索响应中限制列文本长度

Question

以下是我的elasticsearch映射

{
  "metadata" : {
    "mappings" : {
      "properties": {
        "id": {"type":"keyword"},
        "title": {"type":"keyword"},
        "created": {"type":"date"},
        "modified": {"type":"date"},
        "keyword": {"type":"keyword"},
        "description": {"type":"text"}
      }
    }
  }
}

下面是我的ES查询，根据用户对多个字段的查询来检索数据，限制在前5名，按修改日期排序，只显示标题& 描述字段。这个查询完全按照我的期望工作。

GET /_search
{
    "query": {
        "multi_match" : {
            "query" : "UK House Price Index",
            "fields" : ["title", "keyword", "description"]
        }
    },
    "size": 5,
    "_source": ["title", "description"],
    "sort": {"modified": "asc"}
}

我想将描述字段的响应限制在100个字符以内。我是ES的新手。谁能告诉我如何有效地完成这个任务？

Answer 1

您可以使用 highlighting 的相关部分，以获得匹配的 description. 它得到了... fragment_size 设置，这基本上是你想要的字符串连接，有趣的是，默认值为100。

POST long_desc/_doc
{"title":"UK House Price Index","keyword":"UK House Price Index","description":"APM automatically collects in-depth performance metrics and errors from inside your applications. Ingest logs UK House Price Index from popular data sources and easily visualize in preconfigured dashboards."}

GET long_desc/_search
{
  "query": {
    "multi_match": {
      "query": "UK House Price Index",
      "fields": [
        "title",
        "keyword",
        "description"
      ]
    }
  },
  "size": 5,
  "_source": [
    "title"
  ],
  "sort": {
    "modified": "asc"
  },
  "highlight": {
    "pre_tags": "",
    "post_tags": "",
    "fragment_size": 1,
    "fields": {
      "description": {
        "fragment_size": 100,
        "number_of_fragments": 1,
        "fragmenter": "span"
      }
    }
  }
}

产生

[
  {
    "_index":"long_desc",
    "_type":"_doc",
    "_id":"zSWAwnEBPAbzy1R_Uk-I",
    "_score":null,
    "_source":{
      "title":"UK House Price Index"
    },
    "highlight":{
      "description":[
        "Ingest logs UK House Price Index from popular data sources and easily visualize in preconfigured dashboards"
      ]
    }
    ...
  }
]

顺便说一下 pre_ ＆amp; post_tags 默认为 <em> 所以你的前台不需要做任何后期处理，呃，突出显示匹配的内容。我选择了空字符串来保持 description 干净。