[AVRO-1590] [java] AllowNull causes unexpected resolution failure

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.7.7
• Fix Version/s: 1.8.0
• Assignee: Ryan Blue
• Reporter: Ryan Blue
• Created: 20/Sep/14 02:20
• Updated: 01/Feb/16 14:56
• Resolved: 29/Sep/14 22:58

Description

If I try to read data serialized with a hand-written schema using a reflected schema generated by AllowNull, even though all of the individual types can be read. Here is a failing test:

  public static class Point {
    double x;
    double y;
  }

  public static class Circle {
    Point center;
    double radius;
  }

  @Test
  public void testAllowNull() throws Exception {
    new SchemaValidatorBuilder()
        .canBeReadStrategy()
        .validateLatest().validate(
        SchemaBuilder.record("Circle").fields()
            .name("center").type().record("Point").fields()
            .requiredDouble("x")
            .requiredDouble("y")
            .endRecord().noDefault()
            .requiredDouble("radius")
            .endRecord(),
        Arrays.asList(ReflectData.AllowNull.get().getSchema(Circle.class)));
  }

The problem is that the ResolvingGrammarGenerator can't resolve a record with a nullable record unless the two have the same full name.

It is more work, but I think the check should be whether there is a readable record in the union. Another alternative is to special case a nullable union and allow the record-level resolution only in that case.