elastic search result data format-CodePudding

I know there is elastic search pipeline processor can do data transformation, but it's before index the document. Is there similar thing for after search result? My use case is that, I have a document, some fields have very long texts, I simply want to truncate those long texts into shorter texts. But I don't want to do it before index documents because those truncated text would not be searchable. I can certainly do this on my Angular UI code after elastic search returns the result. But I want to see if there is alternative way to let elastic search engine do it for me, before return to Angular.

Any tip appreciate.

CodePudding user response：

You can use the script field for this. First, lets create a sample document

POST sample-index/_doc
{
  "id": 1,
  "text": "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged."
}

Now lets do a query with scripted fields:

GET sample-index/_search
{
  "_source": ["id"], 
  "query": {
    "match": {
      "text": "ipsum"
    }
  },
  "script_fields": {
    "text_summary": {
      "script": "if (params['_source']['text'].length() > 40) { return params['_source']['text'].substring(0,40)   '...'; } else { return  params['_source']['text']; }"
    }
  }
}

The result will be something like this :

{
  "took": 15,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 1,
      "relation": "eq"
    },
    "max_score": 0.39556286,
    "hits": [
      {
        "_index": "sample-index",
        "_id": "ZAhIEoUBNMHtGSRnO4bt",
        "_score": 0.39556286,
        "_ignored": [
          "text.keyword"
        ],
        "_source": {
          "id": 1
        },
        "fields": {
          "text_summary": [
            "Lorem Ipsum is simply dummy text of the ..."
          ]
        }
      }
    ]
  }
}