Throw parsing error if span_term query contains multiple fields

Span term Query, like many other queries, used to parse even when the query referred to multiple fields and the first one would win. We rather throw an exception now instead.
Also modified the parsing code to consume the whole query object.

core/src/main/java/org/elasticsearch/index/query/SpanTermQueryBuilder.java

@@ -94,22 +94,21 @@ public class SpanTermQueryBuilder extends BaseTermQueryBuilder<SpanTermQueryBuil
 
     public static Optional<SpanTermQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException, ParsingException {
         XContentParser parser = parseContext.parser();
-
+        String fieldName = null;
-        XContentParser.Token token = parser.currentToken();
-        if (token == XContentParser.Token.START_OBJECT) {
-            token = parser.nextToken();
-        }
-
-        assert token == XContentParser.Token.FIELD_NAME;
-        String fieldName = parser.currentName();
-
-
         Object value = null;
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
         String queryName = null;
-        token = parser.nextToken();
-        if (token == XContentParser.Token.START_OBJECT) {
         String currentFieldName = null;
+        XContentParser.Token token;
+        while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
+            if (token == XContentParser.Token.FIELD_NAME) {
+                currentFieldName = parser.currentName();
+            } else if (token == XContentParser.Token.START_OBJECT) {
+                if (fieldName != null) {
+                    throw new ParsingException(parser.getTokenLocation(), "[span_term] query doesn't support multiple fields, found ["
+                            + fieldName + "] and [" + currentFieldName + "]");
+                }
+                fieldName = currentFieldName;
                 while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
                     if (token == XContentParser.Token.FIELD_NAME) {
                         currentFieldName = parser.currentName();
@@ -128,15 +127,10 @@ public class SpanTermQueryBuilder extends BaseTermQueryBuilder<SpanTermQueryBuil
                         }
                     }
                 }
-            parser.nextToken();
             } else {
+                fieldName = parser.currentName();
                 value = parser.objectBytes();
-            // move to the next token
-            parser.nextToken();
             }
-
-        if (value == null) {
-            throw new ParsingException(parser.getTokenLocation(), "No value specified for term query");
         }
 
         SpanTermQueryBuilder result = new SpanTermQueryBuilder(fieldName, value);

core/src/test/java/org/elasticsearch/index/query/SpanTermQueryBuilderTests.java

@@ -23,6 +23,7 @@ import org.apache.lucene.index.Term;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.TermQuery;
 import org.apache.lucene.search.spans.SpanTermQuery;
+import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.lucene.BytesRefs;
 import org.elasticsearch.index.mapper.MappedFieldType;
 
@@ -108,4 +109,25 @@ public class SpanTermQueryBuilderTests extends AbstractTermQueryTestCase<SpanTer
         assertEquals(json, "kimchy", parsed.value());
         assertEquals(json, 2.0, parsed.boost(), 0.0001);
     }
+
+    public void testParseFailsWithMultipleFields() throws IOException {
+        String json = "{\n" +
+                "  \"span_term\" : {\n" +
+                "    \"message1\" : {\n" +
+                "      \"term\" : \"this\"\n" +
+                "    },\n" +
+                "    \"message2\" : {\n" +
+                "      \"term\" : \"this\"\n" +
+                "    }\n" +
+                "  }\n" +
+                "}";
+
+        try {
+            parseQuery(json);
+            fail("parseQuery should have failed");
+        } catch(ParsingException e) {
+            assertEquals("[span_term] query doesn't support multiple fields, found [message1] and [message2]", e.getMessage());
+        }
+    }
+
 }