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Migrational

Migrational is a simple and small library which takes advantage of reflection to migrate data in objects.

Maven

If you are using Maven add the following to your pom.xml file Add this in your <repositories> block

<repository>
    <id>lemmotresto</id>
    <url>http://repo.lemmotresto.com/</url>
</repository>

And this in your <dependencies> block

<dependency>
    <groupId>me.max</groupId>
    <artifactId>migrational</artifactId>
    <version>VERSION</version>
</dependency>

Gradle

If you are using Gradle add this to your build.gradle file

dependencies {
    compile 'me.max:migrational:VERSION'
}

repositories {
    maven {
        url "http://repo.lemmotresto.com/"
    }
}

Examples

Field example

This is a field example it uses the @Migratable annotation on fields to show what fields should be migrated.

public class FieldExampleObject {

    @Migratable(key = "name", defaultValue = "Max") private String name = "Lily";
    @Migratable private int age;
    @Migratable(defaultValue = "Netherlands") private String country;

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public String getCountry() {
        return country;
    }

    public static void main(String[] args){
        //'Load' the data in this case just creating a map but in reality you load this from a file.
        Map<String, Object> data = new HashMap<>();
        //name is in there with the key
        //age is in there without a key so it will use the field name
        //country is not in there so defaultValue will be used
        //if no defaultValue present it will use field value
        data.put("name", "Stijn");
        data.put("age", 20);

        //Instantiate the migrator
        Migrator mig = new Migrator(FieldExampleObject.class, data);
        try {
            //Migrate
            mig.migrate();
        } catch (IllegalAccessException | InstantiationException | InvocationTargetException e) {
            e.printStackTrace();
        }
        //Cast the result
        FieldExampleObject result = (FieldExampleObject) mig.getLastMigratedObject();
        //Print the values
        System.out.println(result.getName());
        System.out.println(result.getAge());
        System.out.println(result.getCountry());
    }
}

Class example

This next example uses the @Migratable annotation on the class. This will migrate every field in this class besides the fields annotated with the @Exempt annotation.

//This will migrate every field unless it has the @Exempt annotation.
@Migratable
public class ClassExampleObject {

    //Will migrate
    private String name = "Stijn";
    private boolean isCool = true;
    //Wont migrate
    @Exempt private int age = 27;

    public String getName() {
        return name;
    }

    public boolean isCool() {
        return isCool;
    }

    public int getAge() {
        return age;
    }

    public static void main(String[] args){
        //'Load' the data in this case just creating a map but in reality you load this from a file.
        Map<String, Object> data = new HashMap<>();
        //Only name is in here so isCool will default to it's initialised value (true).
        data.put("name", "Stijn");

        //Instantiate the migrator
        Migrator mig = new Migrator(ClassExampleObject.class, data);
        try {
            //Migrate
            mig.migrate();
        } catch (IllegalAccessException | InstantiationException | InvocationTargetException e) {
            e.printStackTrace();
        }
        //Cast the result
        ClassExampleObject result = (ClassExampleObject) mig.getLastMigratedObject();
        //Print the values
        System.out.println(result.getName());
        System.out.println(result.isCool());
        System.out.println(result.getAge());
    }
}