Java spring boot Jpa error while converting java.sql.Date to java.time.LocalDate

Question

I am using Java 11 and Spring boot v2.3.3.RELEASE. Below is my pom.xml. I am trying to fetch the data from DB function, which will return 2 columns and one row. The columns returned are Date (Postgres SQL).

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.group</groupId>
    <artifactId>artifact</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>11</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt</artifactId>
            <version>0.9.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.11.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.11</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-beanutils/commons-beanutils -->
        <dependency>
            <groupId>commons-beanutils</groupId>
            <artifactId>commons-beanutils</artifactId>
            <version>1.9.4</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

I have the following model class.

import com.fasterxml.jackson.annotation.JsonFormat;

import java.time.LocalDate;


public class CachedDate {
    @JsonFormat(
            shape = JsonFormat.Shape.STRING,
            pattern = "yyyy-MM-dd",
            locale = "en_CA")
    private LocalDate businessDate;
    @JsonFormat(
            shape = JsonFormat.Shape.STRING,
            pattern = "yyyy-MM-dd",
            locale = "en_CA")
    private LocalDate previousBusinessDate;
// constructor/ getter and setter ommited
}

I am having a repository where I am trying to get the data based on DB function call.

Query query = entityManager.createNativeQuery(
        "SELECT * FROM get_function(:date)"
);
query.setParameter("date", date);
List<Object> result = (List<Object>) query.getResultList();
Iterator it = result.iterator();
CachedDate dates = new CachedDate();

while (it.hasNext()) {
    Object[] row = (Object[]) it.next();
    //dates.setBusinessDate((LocalDate) row[0]);
    //dates.setPreviousBusinessDate((LocalDate) row[1]);
     // This gives error 1


    dates.setBusinessDate(LocalDate.parse((String) row[0]));
    dates.setPreviousBusinessDate(LocalDate.parse((String) row[1]));

    // This gives error 2
}

Error 1 :

Caused by: java.lang.ClassCastException: class java.sql.Date cannot be cast to class java.time.LocalDate (java.sql.Date is in module java.sql of loader 'platform'; java.time.LocalDate is in module java.base of loader 'bootstrap')

Error 2 :

Caused by: java.lang.ClassCastException: class java.sql.Date cannot be cast to class java.lang.String (java.sql.Date is in module java.sql of loader 'platform'; java.lang.String is in module java.base of loader 'bootstrap')

What is the issue here? I cannot have the model class as Entity as it is not a object in my DB. It is just what is returned from function. Not sure if that would jave helped though.

Can you please assist here?

Answer 1

The return type of your query is java.sql.Date . You have to cast it first to java.sql.Date then call .toLocalDate() to convert it to LocalDate .

Sample:

   dates.setBusinessDate(((java.sql.Date) row[0]).toLocalDate());
   dates.setPreviousBusinessDate(((java.sql.Date) row[1]).toLocalDate());