One to Many association in Lazy Loading mode

I’m having some problems during the data retrieving of an entity (called Person) that contains a list of another entity (Telecom) in lazy loading mode using the XML MyBatis version.

MyBatis version

3.4.5

Database vendor and version

PostgreSQL 9.6

Test case or example project

Structure of the database: Tables: person, person_telecom (associative table between Person and Telecom), telecom

Database tables scripts:

CREATE TABLE person
(
    id character varying(36) COLLATE pg_catalog."default" NOT NULL DEFAULT (uuid_generate_v1())::character varying,
    CONSTRAINT person_pk PRIMARY KEY (id)
)

CREATE TABLE telecom
(
    id character varying(36) COLLATE pg_catalog."default" NOT NULL DEFAULT (uuid_generate_v1())::character varying,
    tlc_value character varying(50) COLLATE pg_catalog."default" NOT NULL,
    CONSTRAINT telecom_pk PRIMARY KEY (id)
)

CREATE TABLE person_telecom
(
    person_id character varying(36) COLLATE pg_catalog."default" NOT NULL,
    telecom_id character varying(36) COLLATE pg_catalog."default" NOT NULL,
    CONSTRAINT person_telecom_pk PRIMARY KEY (person_id, telecom_id),
    CONSTRAINT person_telecom_personid FOREIGN KEY (person_id) REFERENCES person (id),
    CONSTRAINT person_telecom_telecomid FOREIGN KEY (telecom_id) REFERENCES telecom (id)
)

Data example: Person: id:x

Telecom id:t1 value:123 id:t2 value:345

Person_Telecom person_id:x telecom_id:t1 person_id:x telecom_id:t2

Here is the person resultMap:

<resultMap id="personResultMap" type="Person">
		<id column="p_id" jdbcType="VARCHAR" property="id" />
		<collection property="telecom" column="t_telecom_id" ofType="Telecom" select="com.example.mapper.TelecomMapper.selectByPrimaryKey"/>	
</resultMap>

<select id="selectByPrimaryKey" parameterType="String" resultMap="personResultMap">
		SELECT
		person.id as p_id, telecom.id as t_telecom_id		
		FROM person 		
		LEFT JOIN person_telecom ON person_telecom.person_id = person.id
		WHERE person.id = #{id,jdbcType=VARCHAR}
</select>

Here is the telecom resultMap with the selectByPrimaryKey method:

<resultMap id="telecomResultMap" type="Telecom">
		<id column="tlc_id" jdbcType="VARCHAR" property="id" />		
		<result column="tlc_tlc_value" property="value" jdbcType="VARCHAR" />		
</resultMap>

<select id="selectByPrimaryKey" parameterType="String" resultMap="telecomResultMap">
		select
		tlc.id, tlc.tlc_value
		from telecom tlc
		where tlc.id = #{id,jdbcType=VARCHAR}
</select>

The classes Person and Telecom are simple java beans; the class Person obviously contains an ArrayList of Telecom.

In our scenario there is a Person with two Telecom associated; using the code posted above the result is a Person with only one Telecom associated (the first).

Steps to reproduce

After DB creation and population:

PersonMapper.selectByPrimaryKey(personId);

Expected result

Java class Person instance:

Person  x {
String id = x;
List<Telecom> telecoms = {(t1, 123), (t2, 345)}
}

Actual result

Person  x {
String id = x;
List<Telecom> telecoms = {(t1, 123)}
}

[marcocaminiti]

I have the same problem. Without nested query work fine but with nested query I have the same behavior

[mzocco]

Okay, thanks for the support.