[AVRO-2131] Records with unions with self references fail to parse.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.8.1
• Fix Version/s: 1.9.0
• Component/s: java

Environment

Java 1.8.0_152-b1

• Flags: Patch
• External issue URL: https://github.com/apache/avro/pull/278
• Assignee: Daniel Kulp
• Reporter: Jeff Maxwell
• Created: 17/Jan/18 22:52
• Updated: 29/Nov/18 20:17
• Resolved: 29/Nov/18 20:17

Description

Records with unions with self references fail to parse.

The example below fails to parse with "Type not supported: Node"

[
  {
    "namespace": "tree",
    "type": "record",
    "name": "Node",
    "fields": [
      {
        "name": "left",
        "type": [
          "null",
          {
            "type": "Node"
          }
        ],
        "default": null
      },
      {
        "name": "right",
        "type": [
          "null",
          {
            "type": "Node"
          }
        ],
        "default": null
      }
    ]
  }
]
 

When we don't allow nullability it parses successfully:

[
  {
    "namespace": "tree",
    "type": "record",
    "name": "Node",
    "fields": [
      {
        "name": "left",
        "type": "Node"
      },
      {
        "name": "right",
        "type": "Node"
      }
    ]
  }
]
 

The root cause: When the second element of the union, {"type":"Node"}, is parsed there is no path that can successfully handle the JsonNode.

The solution is to add this logic to the Schema.parse(JsonNode schema, Names names) method:

      } else {  //For unions with self reference
        Name nameFromType = new Name(type, names.space);
        if (names.containsKey(nameFromType)) {
          return names.get(nameFromType);
        }
        throw new SchemaParseException("Type not supported: "+type);
      }

Pull request attached

Issue Links

• links to: GitHub Pull Request #278
• links to: GitHub Pull Request #278