I have 2 Java POJO files
class Filter Variables {
private String id;
private String name;
private List<ValueVariables> variableValues;
getters() setters()
}
class ValueVariables {
private String id;
private String valueListId;
private String value;
}
The database has a FK mapping between FilterVariable.id and ValueVariable.valueListId. Inserts into the table work perfectly, i have a single transaction that inserts into both tables separately. While retrieving the data using select
and join
, I only receive the first row from the table in the database.
Database Tables:
CREATE TABLE IF NOT EXISTS filter_variables (
id VARCHAR(36) NOT NULL,
name VARCHAR(30) NOT NULL,
PRIMARY KEY(id)
);
CREATE TABLE IF NOT EXISTS variable_values (
id INT(10) NOT NULL AUTO_INCREMENT,
valueListId VARCHAR(36) NOT NULL,
value VARCHAR(100) NOT NULL,
PRIMARY KEY(id),
FOREIGN KEY (valueListId) REFERENCES filter_variables(id)
);
<select id="selectFilterVariableById" parameterType="java.lang.String" resultMap="FilterVariablesJoinResultMap">
select FV.id, FV.name, VV.value, VV.valueListId
from filter_variables as FV left outer join variable_values as VV ON FV.id=VV.valueListId
where FV.id = #{id,jdbcType=VARCHAR}
</select>
The method in the interface is defined as List<FilterVariables> selectFilterVariableById(String id);
I understand that with 2 separate I can store values into the two Pojo and use them, but is there any way with joins where I can retrieve multiple rows?
The result map is defined as so:
<resultMap id="FilterVariablesJoinResultMap" type="com.example.mybatissample.FilterVariables">
<id column="id" jdbcType="VARCHAR" property="id" />
<result column="name" jdbcType="VARCHAR" property="name" />
<collection property="variableValues" ofType="com.example.mybatissample.ValueVariables">
<id property="id" column="id"/>
<result property="valueListId" column="valueListId"/>
<result property="value" column="value"/>
</collection>
</resultMap>
This is how the data in mysql looks like.
When a request is made from Java:
List<FilterVariables> vals= filterVariablesMapper.selectFilterVariableById(id);
System.out.println(vals);
System.out.println(vals.size());
I only get the first row
[FilterVariables [id=b218df5c-eac1-4e01-846a-119345bb254d, name=ME, valueId=null, storageRecordType=null, values={b218df5c-eac1-4e01-846a-119345bb254d [email protected]}]]
1
As mentioned by @ave, the solution is to either
The result map is now:
<resultMap id="FilterVariablesJoinResultMap" type="com.example.mybatissample.FilterVariables">
<id column="id" jdbcType="VARCHAR" property="id" />
<result column="name" jdbcType="VARCHAR" property="name" />
<collection property="variableValues" ofType="com.example.mybatissample.ValueVariables">
<id property="varId" column="varId"/>
<result property="valueListId" column="valueListId"/>
<result property="value" column="value"/>
</collection>
</resultMap>
With this the results come as required.
ValueVariable is now:
class ValueVariables {
private String varId;
private String valueListId;
private String value;
getters() and setters()
}
The select query is now:
<select id="selectFilterVariableById" parameterType="java.lang.String" resultMap="FilterVariablesJoinResultMap">
select FV.id, name, description, type, columnId, storageRecordType, valueId,
operator, dbId, sharedValue, systemVariable, VV.id as varId, VV.value, VV.valueListId
from filter_variables as FV left outer join variable_values as VV ON FV.id=VV.valueListId
where FV.id = #{id,jdbcType=VARCHAR}
</select>
Please note that VV.id is to be aliased for this to work.