Java – mybatis custom typehandler is not executed when tags are placed

I have a < resultmap > that uses a custom typehandler as one of the result properties:

<resultMap id="foo" type="hashmap">
    ... 
    <result property="SERVICES_XML" javaType="string" jdbcType="CLOB" typeHandler="com.foo.bar.OracleClobTypeHandler" />
    ...
</resultMap>

No matter which attribute I attach to my handler (I mean, this is not a CLOB specific problem, and I try to use varchar), the handler will not be called when I get the result from the database

I set breakpoints in all methods of the custom handler:

public class OracleClobTypeHandler implements TypeHandler<String> {

  @Override
  public void setParameter(PreparedStatement ps,int i,String parameter,JdbcType jdbcType) throws sqlException {
    log.debug("setParameter called");   <================ BREAKPOINT HERE
  }

  @Override
  public String getResult(ResultSet rs,String columnName)
        throws sqlException {
    log.debug("getResult 2 called");    <================ BREAKPOINT HERE
    return "";
  }

  @Override
  public String getResult(ResultSet rs,int columnIndex)
        throws sqlException {
    log.debug("getResult 2 called");    <================ BREAKPOINT HERE
    return "";
  }

  @Override
  public String getResult(CallableStatement cs,int columnIndex)
        throws sqlException {
    log.debug("getResult 3 called");    <================ BREAKPOINT HERE
    return "";
  }
}

Obviously, the above method was not implemented

I tried to put < typehandler javatype = "Java. Lang. string" JDBC type = "CLOB" handler = "com. Foo. Bar. Oracleclobtypehandler" / > in mybatis < configuration >, but it didn't work I didn't do anything else, including extending typehandler < < Object >, etc

What on earth did I do wrong?

Solution

After a long time of digging, I finally found the answer

This seems to be a mistake in mybatis

In order for your handler to apply to the < result > element, you must explicitly specify the column attribute even if the attribute already matches the column name and field name in the bean For me, it looks like this:

<result property="SERVICES_XML" column="SERVICES_XML" javaType="string" jdbcType="CLOB" typeHandler="com.foo.bar.OracleClobTypeHandler" />

Note that the above changes will also result in handlers defined in < configuration > Tags work, so inline typehandler may no longer be needed - this is my case I'm done:

<configuration>
  <typeHandlers>
    <typeHandler javaType="java.lang.String" jdbcType="CLOB" handler="com.foo.bar.OracleClobTypeHandler"/>        
  </typeHandlers>
</configuration>

and

<result property="SERVICES_XML" column="SERVICES_XML" javaType="string" jdbcType="CLOB" />