Does not work Cursor using annotation based Mapper

[kazuki43zoo]

MyBatis version

3.4.0

Database vendor and version

Any

Test case or example project

N/A

Steps to reproduce

At first, i add method in BoundBlogMapper as follow:

  @Select({
          "SELECT *",
          "FROM blog",
          "ORDER BY id"
  })
  Cursor<Blog> selectCursorBlogs();

At second, i add test method in BindingTest as follow:

  @Test
  public void shouldExecuteWithCursorAndRowBounds() {
    SqlSession session = sqlSessionFactory.openSession();
    try {
      BoundBlogMapper mapper = session.getMapper(BoundBlogMapper.class);
      Cursor<Blog> blogs = mapper.selectCursorBlogs();
      for (Blog b :blogs) {
        System.out.println(b);
      }
    } finally {
      session.close();
    }
  }

Expected result

Blog: 1 : Jim Business (null)
Blog: 2 : Bally Slog (null)

Actual result

org.apache.ibatis.reflection.ReflectionException: Error instantiating interface org.apache.ibatis.cursor.Cursor with invalid types () or values (). Cause: java.lang.NoSuchMethodException: org.apache.ibatis.cursor.Cursor.<init>()

    at org.apache.ibatis.reflection.factory.DefaultObjectFactory.instantiateClass(DefaultObjectFactory.java:90)
    at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:50)
    at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:42)
    at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:594)
    at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:571)
    at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:380)
    at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForSimpleResultMap(DefaultResultSetHandler.java:339)
    at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:314)
    at org.apache.ibatis.cursor.defaults.DefaultCursor.fetchNextObjectFromDatabase(DefaultCursor.java:142)
    at org.apache.ibatis.cursor.defaults.DefaultCursor.fetchNextUsingRowBound(DefaultCursor.java:128)
    at org.apache.ibatis.cursor.defaults.DefaultCursor$CursorIterator.hasNext(DefaultCursor.java:199)
    at org.apache.ibatis.binding.BindingTest.shouldExecuteWithCursorAndRowBounds(BindingTest.java:774)
...
Caused by: java.lang.NoSuchMethodException: org.apache.ibatis.cursor.Cursor.<init>()
    at java.lang.Class.getConstructor0(Class.java:3082)
    at java.lang.Class.getDeclaredConstructor(Class.java:2178)
    at org.apache.ibatis.reflection.factory.DefaultObjectFactory.instantiateClass(DefaultObjectFactory.java:62)

[kazuki43zoo]

I've modified the MapperAnnotationBuilder#getReturnType(Method) (L.393) as follow:

//      if (Collection.class.isAssignableFrom(rawType)) { ← ### Original code ###
      if (Iterable.class.isAssignableFrom(rawType)) { // ← ### Changed code ###
        Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
        if (actualTypeArguments != null && actualTypeArguments.length == 1) {
          Type returnTypeParameter = actualTypeArguments[0];
          if (returnTypeParameter instanceof Class<?>) {
            returnType = (Class<?>) returnTypeParameter;
          } else if (returnTypeParameter instanceof ParameterizedType) {
            // (gcode issue #443) actual type can be a also a parameterized type
            returnType = (Class<?>) ((ParameterizedType) returnTypeParameter).getRawType();
          } else if (returnTypeParameter instanceof GenericArrayType) {
            Class<?> componentType = (Class<?>) ((GenericArrayType) returnTypeParameter).getGenericComponentType();
            // (gcode issue #525) support List<byte[]>
            returnType = Array.newInstance(componentType, 0).getClass();
          }
        }

This code was worked. What do you think ?

[emacarron]

I would check especifically for Cursor instead of for iterable.

2016-04-23 17:57 GMT+02:00 Kazuki Shimizu [email protected]:

I've modified the MapperAnnotationBuilder#getReturnType(Method) (L.393)
as follow:

// if (Collection.class.isAssignableFrom(rawType)) { ← ### Original code ###
if (Collection.class.isAssignableFrom(rawType)
|| Iterable.class.isAssignableFrom(rawType)) { // ← ### Added condition ###
Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
if (actualTypeArguments != null && actualTypeArguments.length == 1) {
Type returnTypeParameter = actualTypeArguments[0];
if (returnTypeParameter instanceof Class) { returnType = (Class) returnTypeParameter;
} else if (returnTypeParameter instanceof ParameterizedType) {
// (gcode issue #443) actual type can be a also a parameterized type
returnType = (Class) ((ParameterizedType) returnTypeParameter).getRawType(); } else if (returnTypeParameter instanceof GenericArrayType) { Class componentType = (Class<?>) ((GenericArrayType) returnTypeParameter).getGenericComponentType();
// (gcode issue #525) support List<byte[]>
returnType = Array.newInstance(componentType, 0).getClass();
}
}

This code was worked. What do you think ?

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#661 (comment)

[kazuki43zoo]

please add milestone!!

[emacarron]

Thanks for pointing @kazuki43zoo !