My Batis Unable to create objects by constructor with collection as argument

[patan12]

MyBatis, Unable to create objects by constructor with collection as argument

I have immuatble classes, I am struct with the below error while instantiating objects.

Tables

      CREATE TABLE employee (
        id varchar NOT NULL,
        "name" varchar NOT NULL
      )
    
      CREATE TABLE muzimil.address (
        id varchar NOT NULL,
        street varchar NOT NULL,
        city varchar NOT NULL,
        emp_id varchar NULL
      )

Java Classes

    @Data
    @Builder
    @AllArgsConstructor
    public class Employee {

      private final String id;
      private final String name;
      private final List<Address> addresses;


    }

    @Data
    @Builder
    @AllArgsConstructor
    public class Address {

      private final String id;
      private final String street;
      private final String city;
      private final String employeeId;

    }

MyBatis: Mapper

  <select id="getById" resultMap="employeeResultMap">
    select
    emp.id as employeeId,
    emp.name as name,
    aa.id as addressId,
    aa.street as street,
    aa.city as city
    from employee emp
    join address aa
    on emp.id=aa.emp_id
    where emp.id = #{id};
  </select>

  <resultMap id="employeeResultMap" type="Employee">
    <constructor>
      <idArg column="employeeId" javaType="String" name="id"/>
      <arg column="name" javaType="String" name="name"/>
      <arg resultMap="addressMap" name="addresses"/>
    </constructor>
  </resultMap>


  <resultMap id="addressMap" type="java.util.List">
    <association property="addresses" javaType="Address">
    <collection property="address" javaType="java.util.ArrayList" ofType="Address">
      <constructor>
        <idArg column="addressId" javaType="String" name="id"/>
        <arg column="street" javaType="String" name="street"/>
        <arg column="city" javaType="String" name="city"/>
        <arg column="employeeId" javaType="String" name="employeeId"/>
      </constructor>
    </collection>
    </association>

  </resultMap>

Error:

Caused by: org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: java.lang.UnsupportedOperationException
### The error may exist in file [/Users/mchavak/Documents/muzimil/POC/postgres/ibatis/build/resources/main/mybatis/mapper/BrandMapper.xml]
### The error may involve com.muzimi.postgres.ibatis.EmployeeMapper.getById
### The error occurred while handling results
### SQL: select     emp.id as employeeId,     emp.name as name,     aa.id as addressId,     aa.street as street,     aa.city as city     from employee emp     join address aa     on emp.id=aa.emp_id     where emp.id = ?;
### Cause: java.lang.UnsupportedOperationException

[harawata]

This may be a duplicate of #101 .
It's a known limitation due to technical difficulties.

[patan12]

@harawata Thanks. is there any work around to achieve this immutable class

[harawata]

There may be several approaches.
I'm not sure if it meets your requirement, but the easiest I can think of is to create a mutable version of Employee class and convert it to immutable in your service layer or in ResultHandler.

  <resultMap type="test.EmployeeMutable" id="employeeMap">
    <id property="id" column="employeeId" />
    <result property="name" column="name" />
    <collection property="addresses" resultMap="addressMap" />
  </resultMap>

  <resultMap type="test.Address" id="addressMap">
    <constructor>
      <idArg column="addressId" javaType="int" />
      <arg column="street" javaType="string" />
      <arg column="city" javaType="string" />
      <arg column="employeeId" javaType="int" />
    </constructor>
  </resultMap>

With this approach, Address is still immutable, so the conversion is relatively easy.

new Employee(
  mutable.getId(),
  mutable.getName(),
  Collections.unmodifiableList(mutable.getAddresses()));

Closing as a duplicate of #101 .