Category Archives: Java

H2 Database: Missing UNIX_TIMESTAMP

So maybe you are running tests using an H2 database with your MySQL-based application, and you just got the message that the MySQL function UNIX_TIMESTAMP(value) is missing from the H2 database? No worries. With an H2 database, you can build your own UNIX_TIMESTAMP (or any other function you might need). I’m here going to show you one way to do it:

First, we need to create a class on the classpath of the application that connects to the H2 database, this is normally the application you are testing:

package h2;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class H2UserDefined {

    public static Long UNIX_TIMESTAMP(String d) throws ParseException {
        DateFormat dateFormat 
                          = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        Date dateresult = dateFormat.parse(d);
        return dateresult.getTime()/1000;
    }
}

Now we need to tell H2 that we have a new function to use. To do this we need some SQL to run against the H2 database:

CREATE ALIAS UNIX_TIMESTAMP FOR "h2.H2UserDefined.UNIX_TIMESTAMP";

Here we tell the H2 database that there is a new alias called UNIX_TIMESTAMP that can be used and that it is located in the package ‘h2’ with the path ‘H2UserDefines’ and a function name UNIX_TIMESTAMP. Quite simple 🙂

Tested on Play Framework 2.3.6, H2 v1.4

Spring Boot: Map JSON body with root node in @RequestBody

Say you have the following JSON:

{
  "rootNode": {
    "firstValue":"",
    "secondValue":""
  }
}

The class to use for this could look something like this:

public class MyValues {
  private String firstValue;
  private String secondValue;
  ...
}

This class will however not map directly to the JSON above via @RequestBody, and this is because the JSON contains a root node (“rootNode”)

The solution here is to wrap the MyValues class into a “root class” like this:

public class MyValuesWrapper {
  MyValues rootNode;
  ...
}

After this you should be able to parse the request body automatically with @ResponseBody like this:

 @PostMapping(value = "/myValues")
  public int postValues(@RequestBody MyValuesWrapper wrappedRequest) {
  
  // Optional: Unwrap for easier access
  MyValues request = wrappedRequest.getMyValues();
  ...

Hope this helps somebody (or me in the future 🙂 )

Tested on Spring Boot v2.3.8 and Java 11

Spring Boot: Create a “RunAllTests” test class with JUnit 5

I like having an easy way to run all tests in a specific package path. I will here show an example of how to create a “RunAllTests” class to use in Spring Boot 2 and JUnit 5 (Jupiter):

package com.niklasottosson.myapp;

import org.junit.platform.runner.JUnitPlatform;
import org.junit.platform.suite.api.SelectPackages;
import org.junit.runner.RunWith;

/**
 * Test class to run all unit tests.
 */
@RunWith(JUnitPlatform.class)
@SelectPackages("com.niklasottosson.myapp.tests")
public class RunAllTests {
}

This will tell JUnit to search the files in the package described (and below) in the @SelectPackages annotation for tests to run

For Spring Boot 2.3.8 the normal “spring-boot-starter-test” dependency was not enough to get the JUnitPlatform into my app (for the @RunWith annotation), so I had to add the following dependency to my pom.xml:

        <dependency>
            <groupId>org.junit.platform</groupId>
            <artifactId>junit-platform-runner</artifactId>
            <version>1.2.0</version>
            <scope>test</scope>
        </dependency>

After all is in place I can run the RunAllUnitTests class and all selected tests runs

Tested on Spring Boot v2.3.8, IntelliJ v2020.3 and JUnit v5 with JUnitPlattform v1.2.0