In the field capabilities API, remove support for providing fields in the request body.

docs/CHANGELOG.asciidoc

@@ -14,6 +14,8 @@
 
 <<remove-suggest-metric, Removed `suggest` metric on stats APIs>> ({pull}29635[#29635])
 
+<<remove-field-caps-body, In field capabilities APIs, removed support for providing fields in the request body>> ({pull}30185[#30185])
+
 === Breaking Java Changes
 
 === Deprecations

docs/reference/migration/migrate_7_0/api.asciidoc

@@ -33,3 +33,10 @@ Previously, `suggest` stats were folded into `search` stats. Support for the
 `suggest` metric on the indices stats and nodes stats APIs remained for
 backwards compatibility. Backwards support for the `suggest` metric was
 deprecated in 6.3.0 and now removed in 7.0.0.
+
+[[remove-field-caps-body]]
+==== In the fields capabilities API, `fields` can no longer be provided in the request body.
+
+In the past, `fields` could be provided either as a parameter, or as part of the request
+body. Specifying `fields` in the request body as opposed to a parameter was deprecated
+in 6.4.0, and is now unsupported in 7.0.0.

docs/reference/search/field-caps.asciidoc

@@ -20,20 +20,6 @@ GET twitter/_field_caps?fields=rating
 // CONSOLE
 // TEST[setup:twitter]
 
-Alternatively the `fields` option can also be defined in the request body. deprecated[6.4.0, Please use a request parameter instead.]
-
-[source,js]
---------------------------------------------------
-POST _field_caps
-{
-   "fields" : ["rating"]
-}
---------------------------------------------------
-// CONSOLE
-// TEST[warning:Specifying a request body is deprecated -- the [fields] request parameter should be used instead.]
-
-This is equivalent to the previous request.
-
 Supported request options:
 
 [horizontal]

rest-api-spec/src/main/resources/rest-api-spec/api/field_caps.json

@@ -35,9 +35,6 @@
         }
       }
     },
-    "body": {
-      "description": "Field json objects containing an array of field names",
-      "required": false
-    }
+    "body": null
   }
 }

server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilitiesRequest.java

@@ -30,7 +30,6 @@
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.ObjectParser;
-import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
 import java.util.Arrays;
@@ -102,10 +101,6 @@ public void writeTo(StreamOutput out) throws IOException {
         }
     }
 
-    public static FieldCapabilitiesRequest parseFields(XContentParser parser) throws IOException {
-        return PARSER.parse(parser, null);
-    }
-
     /**
      * The list of field names to retrieve
      */

server/src/main/java/org/elasticsearch/rest/action/RestFieldCapabilitiesAction.java

@@ -20,25 +20,18 @@
 package org.elasticsearch.rest.action;
 
 import org.elasticsearch.action.fieldcaps.FieldCapabilitiesRequest;
-import org.elasticsearch.action.fieldcaps.FieldCapabilitiesResponse;
 import org.elasticsearch.action.support.IndicesOptions;
 import org.elasticsearch.client.node.NodeClient;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.rest.BaseRestHandler;
-import org.elasticsearch.rest.BytesRestResponse;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestRequest;
-import org.elasticsearch.rest.RestResponse;
-import org.elasticsearch.rest.RestStatus;
 
 import java.io.IOException;
 
 import static org.elasticsearch.rest.RestRequest.Method.GET;
 import static org.elasticsearch.rest.RestRequest.Method.POST;
-import static org.elasticsearch.rest.RestStatus.OK;
 
 public class RestFieldCapabilitiesAction extends BaseRestHandler {
     public RestFieldCapabilitiesAction(Settings settings, RestController controller) {
@@ -57,30 +50,13 @@ public String getName() {
     @Override
     public RestChannelConsumer prepareRequest(final RestRequest request,
                                               final NodeClient client) throws IOException {
-        if (request.hasContentOrSourceParam()) {
-            deprecationLogger.deprecated("Specifying a request body is deprecated -- the" +
-                " [fields] request parameter should be used instead.");
-            if (request.hasParam("fields")) {
-                throw new IllegalArgumentException("can't specify a request body and [fields]" +
-                    " request parameter, either specify a request body or the" +
-                    " [fields] request parameter");
-            }
-        }
+        String[] indices = Strings.splitStringByCommaToArray(request.param("index"));
+        FieldCapabilitiesRequest fieldRequest = new FieldCapabilitiesRequest()
+            .fields(Strings.splitStringByCommaToArray(request.param("fields")))
+            .indices(indices);
 
-        final String[] indices = Strings.splitStringByCommaToArray(request.param("index"));
-        final FieldCapabilitiesRequest fieldRequest;
-        if (request.hasContentOrSourceParam()) {
-            try (XContentParser parser = request.contentOrSourceParamParser()) {
-                fieldRequest = FieldCapabilitiesRequest.parseFields(parser);
-            }
-        } else {
-            fieldRequest = new FieldCapabilitiesRequest();
-            fieldRequest.fields(Strings.splitStringByCommaToArray(request.param("fields")));
-        }
-        fieldRequest.indices(indices);
         fieldRequest.indicesOptions(
-            IndicesOptions.fromRequest(request, fieldRequest.indicesOptions())
-        );
+            IndicesOptions.fromRequest(request, fieldRequest.indicesOptions()));
         return channel -> client.fieldCaps(fieldRequest, new RestToXContentListener<>(channel));
     }
 }