# normalizer(归一化) **[`keyword`](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/keyword.html "Keyword datatype")**** fields**（关键字字段） 的 **`normalizer`**`（`归一化）属性与 [`analyzer`](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/analyzer.html "analyzer")`（`分析器）类似,只不过它保证 **analysis chain**（分析链）生成单一的 **`token `**`（词元`）. **`normalizer`**`（`归一化）应用于索引 **keyword**（关键字）** **之前,以及诸如在 **`[match](https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-match-query.html) query `**(匹配查询),查询解析器搜索 **keyword**** fields**（关键字字段）的时候. | `curl -XPUT ``'localhost:9200/index?pretty'` `-H ``'Content-Type: application/json'` `-d``'` `{` `"settings": {` `"analysis": {` `"normalizer": {` `"my_normalizer": {` `"type": "custom",` `"char_filter": [],` `"filter": ["lowercase", "asciifolding"]` `}` `}` `}` `},` `"mappings": {` `"type": {` `"properties": {` `"foo": {` `"type": "keyword",` `"normalizer": "my_normalizer"` `}` `}` `}` `}` `}` `'` `curl -XPUT ``'localhost:9200/index/type/1?pretty'` `-H ``'Content-Type: application/json'` `-d``'` `{` `"foo": "BÀR"` `}` `'` `curl -XPUT ``'localhost:9200/index/type/2?pretty'` `-H ``'Content-Type: application/json'` `-d``'` `{` `"foo": "bar"` `}` `'` `curl -XPUT ``'localhost:9200/index/type/3?pretty'` `-H ``'Content-Type: application/json'` `-d``'` `{` `"foo": "baz"` `}` `'` `curl -XPOST ``'localhost:9200/index/_refresh?pretty'` `curl -XGET ``'localhost:9200/index/_search?pretty'` `-H ``'Content-Type: application/json'` `-d``'` `{` `"query": {` `"match": {` `"foo": "BAR"` `}` `}` `}` `'` | 上述查询与 **documents（文档） 1** 和 **2** 相匹配,这是因为在索引和查询的时候都将 **`BAR `**转换为了 **`bar`**. | `{` `"took"``: $body.took,` `"timed_out"``: ``false``,` `"_shards"``: {` `"total"``: 5,` `"successful"``: 5,` `"failed"``: 0` `},` `"hits"``: {` `"total"``: 2,` `"max_score"``: 0.2876821,` `"hits"``: [` `{` `"_index"``: ``"index"``,` `"_type"``: ``"type"``,` `"_id"``: ``"2"``,` `"_score"``: 0.2876821,` `"_source"``: {` `"foo"``: ``"bar"` `}` `},` `{` `"_index"``: ``"index"``,` `"_type"``: ``"type"``,` `"_id"``: ``"1"``,` `"_score"``: 0.2876821,` `"_source"``: {` `"foo"``: ``"BÀR"` `}` `}` `]` `}` `}` | 此外,**keywords **在索引之前转换意味着聚合返回 **normalised values**（归一化的值）: | `curl -XGET ``'localhost:9200/index/_search?pretty'` `-H ``'Content-Type: application/json'` `-d``'` `{` `"size": 0,` `"aggs": {` `"foo_terms": {` `"terms": {` `"field": "foo"` `}` `}` `}` `}` `'` | 返回 | `{` `"took"``: 43,` `"timed_out"``: ``false``,` `"_shards"``: {` `"total"``: 5,` `"successful"``: 5,` `"failed"``: 0` `},` `"hits"``: {` `"total"``: 3,` `"max_score"``: 0.0,` `"hits"``: []` `},` `"aggregations"``: {` `"foo_terms"``: {` `"doc_count_error_upper_bound"``: 0,` `"sum_other_doc_count"``: 0,` `"buckets"``: [` `{` `"key"``: ``"bar"``,` `"doc_count"``: 2` `},` `{` `"key"``: ``"baz"``,` `"doc_count"``: 1` `}` `]` `}` `}` `}` |