Serializing `Map`s will produce non-well-formed XML as keys are not modified as per XML name rules

Hello, I can not parse Map to valid XML String if Map contains a key with white space. I am using jackson-dataformat-xml version: 2.5.3

Here is sample code to reproduce this issue:

package com.asite.html;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;

public class Test {
	public static void main(String[] args) throws IOException{
		parseMapWithNoSpace(); //This method works fine
		parseMapWithSpace(); //This method will throw IOException
	}
	private static void parseMapWithNoSpace() throws JsonProcessingException, IOException, JsonParseException, JsonMappingException {
		Map<String, String> mapWithNoSpace = new HashMap<>();
		mapWithNoSpace.put("mapWithNoSpace", "test test"); //Key with no space
		XmlMapper mapper = new XmlMapper();
		String xml = mapper.writeValueAsString(mapWithNoSpace);
		System.out.println(xml);
		Map map1 = mapper.readValue(xml, Map.class);
		System.out.println(map1);
	}

	private static void parseMapWithSpace() throws JsonProcessingException, IOException, JsonParseException, JsonMappingException {
		Map<String, String> mapWithSpace = new HashMap<>();
		mapWithSpace.put("tests pace", "test"); //key with space
		XmlMapper mapper = new XmlMapper();
		String xml = mapper.writeValueAsString(mapWithSpace);
		System.out.println(xml);
		Map map1 = mapper.readValue(xml, Map.class);
		System.out.println(map1);
	}
}

Here is console output

<HashMap xmlns=""><mapWithNoSpace>test test</mapWithNoSpace></HashMap>
{mapWithNoSpace=test test}
<HashMap xmlns=""><test space>test</test space></HashMap>
Exception in thread "main" java.io.IOException: javax.xml.stream.XMLStreamException: ParseError at [row,col]:[1,30]
Message: Attribute name "space" associated with an element type "test" must be followed by the ' = ' character.
	at com.fasterxml.jackson.dataformat.xml.util.StaxUtil.throwXmlAsIOException(StaxUtil.java:24)
	at com.fasterxml.jackson.dataformat.xml.deser.XmlTokenStream.next(XmlTokenStream.java:164)
	at com.fasterxml.jackson.dataformat.xml.deser.FromXmlParser.nextToken(FromXmlParser.java:453)
	at com.fasterxml.jackson.databind.deser.std.MapDeserializer._readAndBindStringMap(MapDeserializer.java:461)
	at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:342)
	at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:26)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3562)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2578)
	at com.asite.html.Test.parseMapWithSpace(Test.java:33)
	at com.asite.html.Test.main(Test.java:15)
Caused by: javax.xml.stream.XMLStreamException: ParseError at [row,col]:[1,30]
Message: Attribute name "space" associated with an element type "test" must be followed by the ' = ' character.
	at com.sun.org.apache.xerces.internal.impl.XMLStreamReaderImpl.next(XMLStreamReaderImpl.java:601)
	at javax.xml.stream.util.StreamReaderDelegate.next(StreamReaderDelegate.java:88)
	at org.codehaus.stax2.ri.Stax2ReaderAdapter.next(Stax2ReaderAdapter.java:129)
	at com.fasterxml.jackson.dataformat.xml.deser.XmlTokenStream._collectUntilTag(XmlTokenStream.java:349)
	at com.fasterxml.jackson.dataformat.xml.deser.XmlTokenStream._next(XmlTokenStream.java:312)
	at com.fasterxml.jackson.dataformat.xml.deser.XmlTokenStream.next(XmlTokenStream.java:162)
	... 8 more

[cfries]

This issue is more severe than it looks. Jackson cannot serialise the following simple Java Data Structures into valid XML:

• Map<LocalDate, Object>
• Map<Integer, Object>
• Map<Double, Object>

etc. The issue being that XML Tags are not allowed to start with a number.

[nitinvavdiya]

@cowtowncoder

I am not generating this XML, XmlMapper does. This is my question, why XmlMapper is generating invalid XML. I can put any String in Map as key.

I am getting this issue while RestTemplate . ie. Client:

ResponseEntity<Map> response = RESTTEMPLATE.postForEntity(INITIALURL + "/getMap", templateParamRequest, Map.class);

Service:

Map<String, String> map = new HashMap<>();
map.put("test space", "test")
return ResponseEntity<>(map, HttpStatus.OK);

I don’t understabd why did you close this issue.