[[breaking_60_rest_changes]]
=== REST changes

==== Unquoted JSON

In previous versions of Elasticsearch, JSON documents were allowed to contain unquoted field names.
This feature was removed in the 5.x series, but a backwards-compatibility layer was added via the
system property `elasticsearch.json.allow_unquoted_field_names`. This backwards-compatibility layer
has been removed in Elasticsearch 6.0.0.

==== Duplicate Keys in JSON, CBOR, Yaml and Smile

In previous versions of Elasticsearch, documents were allowed to contain duplicate keys. Elasticsearch 6.0.0
 enforces that all keys are unique. This applies to all content types: JSON, CBOR, Yaml and Smile.

==== Content-Type Auto-detection

In previous versions of Elasticsearch, having a proper Content-Type for the data in a request was not enforced.
Elasticsearch 6.0.0 enforces that all requests with a body must have a supported Content-Type and this type will
be used when parsing the data.

When using the `source` query string parameter, the `source_content_type` parameter must also be specified with
the media type of the source.

==== Boolean API parameters

All REST APIs parameters (both request parameters and JSON body) support providing boolean "false" as the
value `false` and boolean "true" as the value `true`. All other values will raise an error.

==== Analyze API changes

The deprecated request parameters and plain text in request body has been removed. Define parameters in request body.

==== Support custom normalizer in Analyze API

Analyze API can analyze normalizer and custom normalizer.
In previous versions of Elasticsearch, Analyze API is requiring a `tokenizer` or `analyzer` parameter.
In Elasticsearch 6.0.0, Analyze API can analyze a text as a keyword field with custom normalizer
or if `char_filter`/`filter` is set and `tokenizer`/`analyzer` is not set.

==== Indices exists API

The `ignore_unavailable` and `allow_no_indices` options are no longer accepted
as they could cause undesired results when their values differed from their
defaults.

==== `timestamp` and `ttl` in index requests

`timestamp` and `ttl` are not accepted anymore as parameters of index/update
requests.

==== Refresh requests with one or more shard failures return HTTP 500 response instead of 200

Refresh requests that are broadcast to multiple shards that can have one or more
shards fail during the request now return a 500 response instead of a 200
response in the event there is at least one failure.

==== Delete by Query API requires an explicit query

In previous versions of Elasticsearch, delete by query requests without an explicit query
were accepted, match_all was used as the default query and all documents were deleted
as a result. From version 6.0.0, delete by query requests require an explicit query.

==== DELETE document calls now implicitly create the type

Running `DELETE index/type/id` now implicitly creates `type` with a default
mapping if it did not exist yet.

==== Indices information APIs

Previously it was possible to execute `GET /_aliases,_mappings` or `GET
/myindex/_settings,_alias` by separating mulitple types of requests with commas
in order to retrieve multiple types of information about one or more indices.
This comma-separation for retrieving multiple pieces of information has been
removed.. `GET /_all` can be used to retrieve all aliases, settings, and
mappings for all indices. In order to retrieve only the mappings for an index,
`GET /myindex/_mappings` (or `_aliases`, or `_settings`).

==== Requests to existing endpoints with incorrect HTTP verb now return 405 responses

Issuing a request to an endpoint that exists, but with an incorrect HTTP verb
(such as a `POST` request to `/myindex/_settings`) now returns an HTTP 405
response instead of a 404. An `Allow` header is added to the 405 responses
containing the allowed verbs. For example:

[source,text]
-------------------------------------------
$ curl -v -XPOST 'localhost:9200/my_index/_settings'
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 9200 (#0)
> POST /my_index/_settings HTTP/1.1
> Host: localhost:9200
> User-Agent: curl/7.51.0
> Accept: */*
> 
< HTTP/1.1 405 Method Not Allowed
< Allow: PUT,GET
< content-type: application/json; charset=UTF-8
< content-length: 134
< 
{
  "error" : "Incorrect HTTP method for uri [/my_index/_settings] and method [POST], allowed: [PUT, GET]",
  "status" : 405
}
* Curl_http_done: called premature == 0
* Connection #0 to host localhost left intact
--------------------------------------------

==== Disallow using `_cache` and `_cache_key`

The `_cache` and `_cache_key` options in queries have been deprecated since version 2.0.0 and
have been ignored since then, issuing a deprecation warning. These options have now been completely
removed, so using them now will throw an error.

==== IndexClosedException to return 400 status code

An `IndexClosedException` is returned whenever an api that doesn't support
closed indices (e.g. search) is called passing closed indices as parameters
and `ignore_unavailable` is set to `false`. The response status code returned
in such case changed from `403` to `400`
