1 files changed, 22 insertions, 15 deletions
diff --git a/core/src/main/java/org/elasticsearch/rest/AbstractRestChannel.java b/core/src/main/java/org/elasticsearch/rest/AbstractRestChannel.java
index 4b3505e97e..bdc78c82dd 100644
--- a/core/src/main/java/org/elasticsearch/rest/AbstractRestChannel.java
+++ b/core/src/main/java/org/elasticsearch/rest/AbstractRestChannel.java
@@ -20,7 +20,6 @@ package org.elasticsearch.rest;
 
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.Strings;
-import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
@@ -58,28 +57,37 @@ public abstract class AbstractRestChannel implements RestChannel {
 
     @Override
     public XContentBuilder newBuilder() throws IOException {
-        return newBuilder(request.hasContent() ? request.content() : null, true);
+        return newBuilder(request.getXContentType(), true);
     }
 
     @Override
     public XContentBuilder newErrorBuilder() throws IOException {
         // Disable filtering when building error responses
-        return newBuilder(request.hasContent() ? request.content() : null, false);
+        return newBuilder(request.getXContentType(), false);
     }
 
+    /**
+     * Creates a new {@link XContentBuilder} for a response to be sent using this channel. The builder's type is determined by the following
+     * logic. If the request has a format parameter that will be used to attempt to map to an {@link XContentType}. If there is no format
+     * parameter, the HTTP Accept header is checked to see if it can be matched to a {@link XContentType}. If this first attempt to map
+     * fails, the request content type will be used if the value is not {@code null}; if the value is {@code null} the output format falls
+     * back to JSON.
+     */
     @Override
-    public XContentBuilder newBuilder(@Nullable BytesReference autoDetectSource, boolean useFiltering) throws IOException {
-        XContentType contentType = XContentType.fromMediaTypeOrFormat(format);
-        if (contentType == null) {
-            // try and guess it from the auto detect source
-            if (autoDetectSource != null) {
-                contentType = XContentFactory.xContentType(autoDetectSource);
+    public XContentBuilder newBuilder(@Nullable XContentType requestContentType, boolean useFiltering) throws IOException {
+        // try to determine the response content type from the media type or the format query string parameter, with the format parameter
+        // taking precedence over the Accept header
+        XContentType responseContentType = XContentType.fromMediaTypeOrFormat(format);
+        if (responseContentType == null) {
+            if (requestContentType != null) {
+                // if there was a parsed content-type for the incoming request use that since no format was specified using the query
+                // string parameter or the HTTP Accept header
+                responseContentType = requestContentType;
+            } else {
+                // default to JSON output when all else fails
+                responseContentType = XContentType.JSON;
             }
         }
-        if (contentType == null) {
-            // default to JSON
-            contentType = XContentType.JSON;
-        }
 
         Set<String> includes = Collections.emptySet();
         Set<String> excludes = Collections.emptySet();
@@ -89,7 +97,7 @@ public abstract class AbstractRestChannel implements RestChannel {
             excludes = filters.stream().filter(EXCLUDE_FILTER).map(f -> f.substring(1)).collect(toSet());
         }
 
-        XContentBuilder builder = new XContentBuilder(XContentFactory.xContent(contentType), bytesOutput(), includes, excludes);
+        XContentBuilder builder = new XContentBuilder(XContentFactory.xContent(responseContentType), bytesOutput(), includes, excludes);
         if (pretty) {
             builder.prettyPrint().lfAtEnd();
         }
@@ -125,5 +133,4 @@ public abstract class AbstractRestChannel implements RestChannel {
     public boolean detailedErrorsEnabled() {
         return detailedErrorsEnabled;
     }
-
 }