IllegalStateException: Cannot convert value of type 'java.sql.Timestamp' to required type 'java.time.LocalDateTime' for property - spring

Question

I'm working on an spring-boot/jpa/ mysql project. Now so far everything worked with DateTime objects when fetching/storing objects with the repository.
The problem has now occured when I use the Jdbc Template to execute a custom sql query.
org.springframework.beans.ConversionNotSupportedException: Failed to convert property
value of type 'java.sql.Timestamp' to required type java.time.LocalDateTime' for
property 'from_time': no matching editors or conversion strategy found
The idea is to fetch Time slots (has a start time and duration in minutes) that are overlapping with a new incoming entry.
To get back my objects I was first using a BeanPropertyMapper and then switched to a custom NestedRowMapper.
The resulting conflicting time slots I want to get look like this:
{
id: 1
comment: "i worked 60minutes"
from_time: "2018-06-16 13:00"
duration_minutes: 60
task: {
name: "My task"
...
}
}
This is the method where I run into the issue:
public List<TimeSlot> getOverlappingEntries(TimeSlot timeslot) throws SQLException {
String sql = "SELECT time_slot.comment, time_slot.from_time,"
+ "DATE_ADD(from_time, INTERVAL duration_minutes MINUTE) AS end_time, "
+ " task.name as `task.name`, task.category as `task.category` "
+ " FROM `time_slot` " + " INNER JOIN task on task.id = time_slot.task_id "
+ " WHERE person_id = ? "
+ " HAVING ? < end_time AND DATE_ADD(? ,INTERVAL ? MINUTE) > from_time;";
PreparedStatementCreator prepared = (con) -> {
PreparedStatement prep = con.prepareStatement(sql);
prep.setObject(1, timeslot.person.id);
prep.setObject(2, timeslot.from_time);
prep.setObject(3, timeslot.from_time);
prep.setObject(4, timeslot.durationMinutes);
logger.info(prep.toString());
return prep;
};
return this.connector.query(prepared, NestedRowMapper.get(TimeSlot.class));
}
Now I would imagine spring is capable of converting those objects easily. And anyway there is the simple way of timestamp.toLocalDateTime() to do so. The problem seems more how to register this as a converter service or how to fix spring-boot configuration to do so.
I tried already a custom converter service but that didn't help:
#javax.persistence.Converter
public class SqlTimestampToLocalDateTimeConverter implements Converter<Timestamp,
LocalDateTime>, AttributeConverter<Timestamp, LocalDateTime> {
#Convert
#Override
public LocalDateTime convert(Timestamp source) {
return source.toLocalDateTime();
}
#Override
public LocalDateTime convertToDatabaseColumn(Timestamp attribute) {
return attribute.toLocalDateTime();
}
#Override
public Timestamp convertToEntityAttribute(LocalDateTime dbData) {
return Timestamp.valueOf(dbData);
}
}
Also many other answers on the internet mentioned that this was already implemented with spring framework 4.x.
The dependencies in the project look like this (build.gradle):
dependencies {
compile "org.springframework.boot:spring-boot-starter-thymeleaf:2.0.2.RELEASE"
compile "org.springframework.boot:spring-boot-starter-web:2.0.2.RELEASE"
compile "org.springframework.boot:spring-boot-starter-security:2.0.2.RELEASE"
compile "org.springframework.boot:spring-boot-starter-data-jpa:2.0.2.RELEASE"
compile "mysql:mysql-connector-java:5.1.46"
compileOnly "org.springframework.boot:spring-boot-devtools:2.0.2.RELEASE"
compile 'org.springframework.data:spring-data-rest-webmvc:3.0.7.RELEASE'
compile 'com.querydsl:querydsl-jpa:4.1.4'
compile 'com.querydsl:querydsl-apt:4.1.4:jpa'
testCompile("junit:junit")
testCompile("org.springframework.boot:spring-boot-starter-test")
testCompile("org.springframework.security:spring-security-test")
}
Thank you for any hints, how to solve this!
/edit:
I think I see a possible workaround now. What I could do is just to fetch the id's of all time slots and then use the repository to fetch the actual objects with their data (also their task objects).
But that feels definitely not like the optimal solution...
This is the NestedRowMapper I use:
import org.springframework.beans.*;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.support.JdbcUtils;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
public class NestedRowMapper<T> implements RowMapper<T> {
private Class<T> mappedClass;
public static <T> NestedRowMapper<T> get(Class<T> mappedClass) {
return new NestedRowMapper<>(mappedClass);
}
public NestedRowMapper(Class<T> mappedClass) {
this.mappedClass = mappedClass;
}
#Override
public T mapRow(ResultSet rs, int rowNum) throws SQLException {
try {
T mappedObject = this.mappedClass.newInstance();;
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(mappedObject);
bw.setAutoGrowNestedPaths(true);
ResultSetMetaData meta_data = rs.getMetaData();
int columnCount = meta_data.getColumnCount();
for (int index = 1; index <= columnCount; index++) {
try {
String column = JdbcUtils.lookupColumnName(meta_data, index);
Object value = JdbcUtils.getResultSetValue(rs, index, Class.forName(meta_data
.getColumnClassName(index)));
bw.setPropertyValue(column, value);
} catch (TypeMismatchException | NotWritablePropertyException
| ClassNotFoundException e) {
e.printStackTrace();
}
}
return mappedObject;
} catch (InstantiationException | IllegalAccessException e1) {
throw new RuntimeException(e1);
}
}
}

Answer 1

You're on the right lines that you can define a RowMapper that tells your app what type of object each column needs to be mapped to. I would recommend trying to use JdbcTemplate.query method: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/jdbc/core/JdbcTemplate.html#query-java.lang.String-java.lang.Object:A-org.springframework.jdbc.core.RowMapper-
You will need to define a RowMapper (not necessarily a NestedRowMapper, you could try ParameterizedRowMapper), then pass that into query with your SQL and WHERE conditions mapped as args.

Answer 2

I think the bast way to use BeanPropertyRowMapper.newInstance(TimeSlot.class) in your getOverlappingEntries method

Answer 3

try this on NestedRowMapper.mapRow
if (value instanceof Timestamp) value = ((Timestamp) value).toLocalDateTime();