Can't map all fields to text type

Elastic Stack Elasticsearch
1

I am trying to map all fields as text. Based on the docs, this should work, but it doesn't:

PUT my_type
{
  "mappings": {
    "my_type": {
      "dynamic_templates": [
        {
          "longs_as_strings": {
            "match_mapping_type": "*",
            "match":   "*",
            "mapping": {
              "type": "text"
            }
          }
        }
      ]
    }
  }
}

PUT my_type/my_type/1
{
  "intfield": 5
}

GET my_type/_search

Results in:

{
  "took": 1,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 1,
    "hits": [
      {
        "_index": "my_type",
        "_type": "my_type",
        "_id": "1",
        "_score": 1,
        "_source": {
          "intfield": 5
        }
      }
    ]
  }
}
2

Check what the mapping looks like by runniung GET /my_type/_mapping/my_type. Elasticsearch will not modify the source document, but that does not mean it is not correctly mapped.