PUT t
{
  "mappings": {
    "t": {
      "dynamic_templates": [
        {
          "strings": {
            "match_mapping_type": "string",
            "mapping": {
              "analyzer": "english",
              "type": "keyword"
            }
          }
        }
      ]
    }
  }
}

PUT t/t/1
{
  "foo": "bar"
}