REST API: Allow to provide case parameter, with camelCase to return results in CamelCasing, closes #162.

Author: kimchy

modules/elasticsearch/src/main/java/org/elasticsearch/rest/action/support/RestXContentBuilder.java

@@ -23,6 +23,7 @@
 import org.elasticsearch.util.xcontent.XContentFactory;
 import org.elasticsearch.util.xcontent.XContentType;
 import org.elasticsearch.util.xcontent.builder.BinaryXContentBuilder;
+import org.elasticsearch.util.xcontent.builder.XContentBuilder;
 
 import java.io.IOException;
 
@@ -47,6 +48,14 @@ public static BinaryXContentBuilder restContentBuilder(RestRequest request) thro
         if (request.paramAsBoolean("pretty", false)) {
             builder.prettyPrint();
         }
+        String casing = request.param("case");
+        if (casing != null && "camelCase".equals(casing)) {
+            builder.fieldCaseConversion(XContentBuilder.FieldCaseConversion.CAMELCASE);
+        } else {
+            // we expect all REST interfaces to write results in underscore casing, so
+            // no need for double casing
+            builder.fieldCaseConversion(XContentBuilder.FieldCaseConversion.NONE);
+        }
         return builder;
     }
 }