Generic type parameter is not correctly resolved when the class hierarchy is deeper than 3 levels.

[pavelda2]

MyBatis version

Probably all (Tested on 3.4.6 and 3.5.0-SNAPSHOT)

Database vendor and version

Probably all (Tested on ORACLE and HSQLDB)

Test case or example project

Pull request #1259

Steps to reproduce

Run test case from pull request #1259

Expected result

MyBatis should automap NUMERIC database type to corresponding Java type based on class inheritance.

MyBatis can do that when generic filed is specified in parent class or parent of parent class. But when generically typed field is specified in higher level of inheritance, MyBatis does not recognize generic type correctly and automaps default type for NUMERIC database type, which is BigDecimal.

Actual result

NUMERIC results in BigDeciaml instead of Integer.

[kazuki43zoo]

Probably, the TypeParameterResolver#resolveReturnType does not return a correct type.
I've tried following tests.

@Test
public void concrete1() throws NoSuchMethodException {
  Assert.assertEquals(Integer.class.getName(), TypeParameterResolver
      .resolveReturnType(Concrete1.class.getMethod("getId"), Concrete1.class).getTypeName());
}

@Test
public void concrete2() throws NoSuchMethodException {
  Assert.assertEquals(Integer.class.getName(), TypeParameterResolver
      .resolveReturnType(Concrete1.class.getMethod("getId"), Concrete2.class).getTypeName());
}

@Test
public void concrete3() throws NoSuchMethodException {
  Assert.assertEquals(Integer.class.getName(), TypeParameterResolver
      .resolveReturnType(Concrete1.class.getMethod("getId"), Concrete3.class).getTypeName());
}

concrete1 and concrete2 are successful.But concrete3 is failed.

[harawata]

Thank you for the test case, @pavelda2 !
It really helps. :)

As @kazuki43zoo pointed out, there seems to be a bug in TypeParameterResolver.
I'll look into it.

[harawata]

Hi @pavelda2 ,
I committed a simpler test case, but verified the fix with your test cases as well.
It would be great if you could test your solution with the latest snapshot to verify the fix.
Thank you!

[pavelda2]

Hi @harawata, latest snapshot fixed the problem in my solution. Thank you.