jonpereiradev / diff-objects

API to compare the difference between two objects

Diff Objects

This project helps you to build functionalities that needs to show the differences between two objects. You can use this project in two ways:

• using the annotations @DiffMappings, @DiffMapping and @DiffProperty;
• using the DiffBuilder to map the properties of a class;

Installation

<dependency>
    <groupId>com.github.jonpereiradev</groupId>
    <artifactId>diff-objects</artifactId>
    <version>1.3.0</version>
</dependency>

DiffBuilder

The DiffBuilder provides an API to map an object without the use of annotations:

Example

public class User {
    
    private final String login;
    private final String password;
    private final LocalDate birthday;
    private final Boolean active;
    private final List<Email> emails;
    
    // getters and constructor ommited ...
}

public class Email {
    
    private final String description;
    private final Boolean active;
    
    // getters and constructor ommited ...
}

import com.github.jonpereiradev.diffobjects.DiffConfig;

public class Main {

    public static void main(String[] args) {
        User u1 = new User("user1", "123456", LocalDate.now().minusDays(1), true);
        User u2 = new User("user2", "12345678", LocalDate.now(), true);

        u1.getEmails().add(new Email("[e-mail]", true));
        u2.getEmails().add(new Email("[e-mail]", false));

        DiffConfig configuration = DiffBuilder
                .map(User.class)
                .mapping("login")
                .mapping("password")
                .mapping("emails", "description")
                .configuration();

        List<DiffResult> diffs = DiffObjects.forClass(User.class).diff(u1, u2, configuration);

        for (DiffResult diff : diffs) {
            if (!diff.isEquals()) {
                System.out.println("Field: " + diff.getProperties().get("field"));
                System.out.println("Before: " + diff.getBefore());
                System.out.println("After: " + diff.getAfter());
            }
        }
    }
}

Annotations

The annotations provided by the diff objects are:

• DiffMappings: to map multiple properties of an object relationship;
• DiffMapping: to map a method of an object;
• DiffProperty: to add properties that will be on the diff result for access;

Example

public class User {
    
    // fields and constructor ommited ...
    
    @DiffMapping
    public String getLogin() {
        return login;
    }
    
    @DiffMapping
    public String getPassword() {
        return password;
    }
    
    @DiffMapping
    public LocalDate getBirthday() {
        return birthday;
    }
    
    @DiffMapping
    public Boolean getActive() {
        return active;
    }
    
    @DiffMapping(value = "description")
    public List<Email> getEmails() {
        return emails;
    }
}

public class Main {
    
    public static void main(String[] args) {
        User u1 = new User("user1", "123456", LocalDate.now().minusDays(1), true);
        User u2 = new User("user2", "12345678", LocalDate.now(), true);
        
        u1.getEmails().add(new Email("[e-mail]", true));
        u2.getEmails().add(new Email("[e-mail]", false));
        
        List<DiffResult> diffs = (DiffObjects).forClass(User.class).diff(u1, u2);
        
        for (DiffResult diff : diffs) {
            if (!diff.isEquals()) {
                System.out.println("Field: " + diff.getProperties().get("field"));
                System.out.println("Before: " + diff.getBefore());
                System.out.println("After: " + diff.getAfter());
            }
        }
    }
}

@DiffProperty

This annotations is used to provide information in the DiffResult about the field. All objects already have the property "field" with the field name as value.

@DiffProperty(key = "field", value = "{{fieldName}}")

Example

public class User {
    
    // code ommited ...
    
    @DiffMapping(value = "description", properties = {
        @DiffProperty(key = "id", value = "E-mail:"),
        @DiffProperty(key = "maxlength", value = "50")
    })
    public List<Email> getEmails() {
        return emails;
    }
}

public class Main {
    
    public static void main(String[] args) {
        // code omitted ...
        
        List<DiffResult> diffs = DiffObjects.diff(u1, u2);
        
        for (DiffResult diff : diffs) {
            if (diff.getProperties().containsKey("id")) {
                String id = diff.getProperties().get("id");
                String maxlength = diff.getProperties().get("maxlength");
            
                System.out.println("Id: " + id);
                System.out.println("Maxlength: " + maxlength);
                System.out.println("Field: " + diff.getProperties().get("field"));
                System.out.println("Before: " + diff.getBefore());
                System.out.println("After: " + diff.getAfter());
            }
        }
    }
}

License

Diff-Objects is available under the MIT license.