Fix if parameterType is simple type, then throws java.lang.NoSuchMeth…

[abel533]

Fix if parameterType is simple type, then throws java.lang.NoSuchMethodException: xxx.();

Recreate the problem, in nested query:

<resultMap id="userRoleMapSelect" extends="userMap" type="tk.mybatis.simple.model.SysUser">
	<association property="role" 
		 select="selectRoleById" 
		 javaType="tk.mybatis.simple.model.SysRole"
	         column="{id=role_id}"/>
</resultMap>
<!-- if you doesn't set parameterType, the default value is null, then it will use HashMap -->
<select id="selectRoleById" parameterType="long" 
            resultMap="tk.mybatis.simple.mapper.RoleMapper.roleMap">
    select * from sys_role where id = #{id}
</select>

the selectRoleById also can be use in annotation:

@Select({"select id,role_name roleName, enabled, create_by createBy, create_time createTime",
		 "from sys_role",
		 "where id = #{id}"})
//default parameterType is Long
SysRole selectById(Long id);

[kazuki43zoo]

Hi @abel533, Thanks for contributing !!
Could you add tests ?

[kazuki43zoo]

Hi @abel533 , Probably you can resolve this issue using single parameter instead of composite parameter(such as {property=column}) as follow:

<resultMap id="userRoleMapSelect" extends="userMap" type="tk.mybatis.simple.model.SysUser">
	<association property="role" 
		 select="selectRoleById" 
		 javaType="tk.mybatis.simple.model.SysRole"
-	         column="{id=role_id}"/>
+	         column="role_id"/>

[kazuki43zoo]

Hi @abel533, I think your fix is not appropriate because the ObjectFactory has no responsibility for creating to an un-assignable type instance. In other words, I think should not converted to the HashMap from a simple type(such as the Long) using the ObjectFactory.

As alternative, I will propose to fix at the DefaultResultSetHandler#instantiateParameterObject method as follow:

private Object instantiateParameterObject(Class<?> parameterType) {
  if (parameterType == null) {
    return new HashMap<Object, Object>();
+ } else if (SimpleTypeRegistry.isSimpleType(parameterType)
+     || typeHandlerRegistry.hasTypeHandler(parameterType)) {
+   return new HashMap<Object, Object>();
  } else if (ParamMap.class.equals(parameterType)) {
    return new HashMap<Object, Object>(); // issue #649
  } else {
    return objectFactory.create(parameterType);
  }
}

@emacarron @harawata, What do you think about my opinion ? I want to hear everyone opinion.
Thanks.

[harawata]

In that example, parameterType="long" is incorrect.
In my opinion, users should use correct parameterType or omit parameterType (parameterType is optional).

I encourage users to omit parameterType.

• If parameterType is omitted, MyBatis uses the actual runtime parameter type.
• If the right parameterType is specified, the result will be the same as the above.
• If a wrong parameterType is specified, the statement will fail.

So, it is better/safer to omit parameterType.

[kazuki43zoo]

@harawata , thanks you for replying !!

In my opinion, users should use correct parameterType or omit parameterType (parameterType is optional).

I encourage users to omit parameterType.

Ok, i agree with your opinion. In this case ... , we should choose from following solutions.

• Omit the parameterType attribute on select element <- @harawata 's suggestion
• Change to use the single parameter (column="role_id") <- my suggestion

Probably, if nested query has been implemented on @Select annotation, we should be used the single parameter model as follow:

@Results(
    @Result(property = "role", one = @One(select = "selectRoleById"), column = "role_id")
)
@Select("select * sys_user where id = #{id}")
SysUser selectUser(Long id);

@Select("select * from sys_role where id = #{id}")
SysRole selectRoleById(Long id);

[wuwen5]

As mentioned here: https://github.com/mybatis/mybatis-3/blob/master/src/test/java/org/apache/ibatis/submitted/complex_column/Person.xml#L45

In that example, because it using RAW, so the paremter is a SysUser,is my understanding correct ?

[harawata]

@wuwen5 ,

In that example,
When the select statement is called directly, the actual parameter is a long.
When the select statement is called as a nested select of the result map 'userRoleMapSelect', the actual parameter is a map.

Regarding the difference between raw and dynamic statement, please see Eduardo's explanation here.

[wuwen5]

Thank you! @harawata.

[abel533]

@kazuki43zoo I think your fix is appropriate. You can fix it in your way.
I will close this PR.