Elasticsearch - Extracting PDF content and encoding with base64

This didn't work :

curl -X PUT "http://localhost:9200/docs/attachment/_mapping" -d '{                  "attachment": {                     "properties" : {                     "content" : {                           "type" : "attachment",                           "fields" : {                               "title" : {"store":"yes"},                               "content":{                                   "type":"string",                                   "term_vector":"with_positions_offsets",                                    "store":"yes"}                               }                            }                        }                    }                }'

This worked, and I can see the content of the PDF through Kibana :

curl -X PUT "http://localhost:9200/docs" -d '{                              "mappings" : {                                "attachment" : {                                  "properties" : {                                    "content" : {                                      "type" : "attachment",                                      "fields" : {                                        "content"  : { "store" : "yes" },                                        "author"   : { "store" : "yes" },                                        "title"    : { "store" : "yes"},                                        "date"     : { "store" : "yes" },                                        "keywords" : { "store" : "yes", "analyzer" : "keyword" },                                        "name"    : { "store" : "yes" },                                        "content_length" : { "store" : "yes" },                                        "content_type" : { "store" : "yes" }                                      }                                    }                                  }                                }                              }                            }'