NPE if "content" is missing in mapper-attachment plugin

Curl recreation:

        curl -X DELETE "localhost:9200/test"

        curl -X PUT "localhost:9200/test" -d '{
          "settings" : { "index" : { "number_of_shards" : 1, "number_of_replicas" : 0 }}
        }'

        curl -X GET "localhost:9200/_cluster/health?wait_for_status=green&pretty=1&timeout=5s"

        curl -X PUT "localhost:9200/test/attachment/_mapping" -d '{
          "attachment" : {
            "properties" : {
              "file" : {
                "type" : "attachment"
              }
            }
          }
        }'

        curl -X PUT "localhost:9200/test/attachment/1" -d '{
            "file" : {
                "_content_type" : "application/pdf",
                "_name" : "resource/name/of/my.pdf"
            }
        }
        '

Produces a:

        {"error":"NullPointerException[null]","status":500}

And in ES logs:

      [2013-02-20 12:49:04,445][DEBUG][action.index             ] [Drake, Frank] [test][0], node[LI6crwNKQmu1ue1u7mlqGA], [P], s[STARTED]: Failed to execute [index {[test][attachment][1], source[{
          "file" : {
              "_content_type" : "application/pdf",
              "_name" : "resource/name/of/my.pdf"
          }
      }
      ]}]
      java.lang.NullPointerException
      	at org.elasticsearch.common.io.FastByteArrayInputStream.<init>(FastByteArrayInputStream.java:90)
      	at org.elasticsearch.index.mapper.attachment.AttachmentMapper.parse(AttachmentMapper.java:309)
      	at org.elasticsearch.index.mapper.object.ObjectMapper.serializeObject(ObjectMapper.java:507)
      	at org.elasticsearch.index.mapper.object.ObjectMapper.parse(ObjectMapper.java:449)
      	at org.elasticsearch.index.mapper.DocumentMapper.parse(DocumentMapper.java:486)
      	at org.elasticsearch.index.mapper.DocumentMapper.parse(DocumentMapper.java:430)
      	at org.elasticsearch.index.shard.service.InternalIndexShard.prepareIndex(InternalIndexShard.java:318)
      	at org.elasticsearch.action.index.TransportIndexAction.shardOperationOnPrimary(TransportIndexAction.java:203)
      	at org.elasticsearch.action.support.replication.TransportShardReplicationOperationAction$AsyncShardOperationAction.performOnPrimary(TransportShardReplicationOperationAction.java:531)
      	at org.elasticsearch.action.support.replication.TransportShardReplicationOperationAction$AsyncShardOperationAction$1.run(TransportShardReplicationOperationAction.java:429)
      	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
      	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
      	at java.lang.Thread.run(Thread.java:680)

Closes #23

src/main/java/org/elasticsearch/index/mapper/attachment/AttachmentMapper.java

@@ -295,6 +295,11 @@ public class AttachmentMapper implements Mapper {
             }
         }
 
+        // Throw clean exception when no content is provided Fix #23
+        if (content == null) {
+            throw new MapperParsingException("No content is provided.");
+        }
+
         Metadata metadata = new Metadata();
         if (contentType != null) {
             metadata.add(Metadata.CONTENT_TYPE, contentType);

src/test/java/org/elasticsearch/plugin/mapper/attachments/test/SimpleAttachmentIntegrationTests.java

@@ -25,6 +25,7 @@ import org.elasticsearch.action.count.CountResponse;
 import org.elasticsearch.common.logging.ESLogger;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.network.NetworkUtils;
+import org.elasticsearch.index.mapper.MapperParsingException;
 import org.elasticsearch.node.Node;
 import org.testng.annotations.*;
 
@@ -133,4 +134,19 @@ public class SimpleAttachmentIntegrationTests {
         countResponse = node.client().count(countRequest("test").query(fieldQuery("file", "End"))).actionGet();
         assertThat(countResponse.count(), equalTo(1l));
     }
-}
+
+    /**
+     * Test case for issue https://github.com/elasticsearch/elasticsearch-mapper-attachments/issues/23
+     * <br/>We throw a nicer exception when no content is provided
+     * @throws Exception
+     */
+    @Test(expectedExceptions = MapperParsingException.class)
+    public void testNoContent() throws Exception {
+        String mapping = copyToStringFromClasspath("/org/elasticsearch/index/mapper/xcontent/test-mapping.json");
+
+        node.client().admin().indices().putMapping(putMappingRequest("test").type("person").source(mapping)).actionGet();
+
+        node.client().index(indexRequest("test").type("person")
+                .source(jsonBuilder().startObject().field("file").startObject().endObject())).actionGet();
+    }
+}