Use Elasticsearch Highlighting feature to show snippets of where terms matched

[derekenos]

By enabling the Elasticsearch Highlighting feature, we can show previews of the context in which a search term matched, with the terms themselves visually highlighted.

For example, the following query:

{
  "query": {
    "match": {
      "full_text": "science"
    }
  },
  "size": 1,
  "_source": false,
  "highlight": {
    "fields": {
      "full_text": {
        "pre_tags": [
          "<b>"
        ],
        "post_tags": [
          "</b>"
        ]
      }
    }
  }
}

executed with:

curl -XPOST https://cb-elasticsearch.derekenos.com:9200/moscon/_search -H "content-type: application/json" -d '{"query":{"match":{"full_text":"science"}},"size":1,"_source":false,"highlight":{"fields":{"full_text":{"pre_tags":["<b>"],"post_tags":["</b>"]}}}}'

yields the response:

{
  "took": 170,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 22,
      "relation": "eq"
    },
    "max_score": 0.047733817,
    "hits": [
      {
        "_index": "moscon",
        "_type": "_doc",
        "_id": "moscon19-1997_000",
        "_score": 0.047733817,
        "highlight": {
          "full_text": [
            ". here as our author and\n\n<b>science</b> guests of honor.",
            "As a costumer, Betty has won scads of awards at <b>science</b> fiction costume events.",
            "She works at the Owen <b>Science</b> & Engineering Library at WSU.",
            "He is also the editor of a . new <b>science</b> fiction magazine, Tomorrow.",
            "MosCon XIX Program Book\n\n17\n\nChanges in <b>Science</b>: <b>Science</b> Guest of Honor Poul Anderson has spent a long"
          ]
        }
      }
    ]
  }
}

With the formatted snippets looking like this:

---

. here as our author and

science guests of honor.

---

As a costumer, Betty has won scads of awards at science fiction costume events.

---

She works at the Owen Science & Engineering Library at WSU.

---

He is also the editor of a . new science fiction magazine, Tomorrow.

---

MosCon XIX Program Book

17

Changes in Science: Science Guest of Honor Poul Anderson has spent a long