Javers Comparing List In Order

问题

I have two java classes like so:

public class FooA {
  private List<FooB> fooB;
}

public class FooB {
  private Integer id;
  private String name;
  private double num;
}

I want to compare the FooA and it tell me what fields inside the list object changed. But when I do this:

FooA old = new FooA(Arrays.asList(new FooB(1, "old", 1.0)));
FooA new = new FooA(Arrays.asList(new FooB(1, "new", 1.0)));

Javers javers = JaversBuilder.javers()
          .withListCompareAlgorithm(LEVENSHTEIN_DISTANCE)
          .build();

javers.compare(old, new);

It gives me this diff:

Diff:
* new object: com.FooA/#fooB/1d32d18fcb3ba2f7f7cb41af6cd96b32
* object removed: com.FooA/#fooB/223ef3c3249fe2898ac3354f9bf42620
* changes on com.FooA/ :
  - 'fooB' collection changes :
    . 'com.FooA/#fooB/223ef3c3249fe2898ac3354f9bf42620' removed
    . 'com.FooA/#fooB/1d32d18fcb3ba2f7f7cb41af6cd96b32' added

I even tried adding an Id on FooB like I've read in a lot of posts. So now my foob looks like this:

public class FooB {
  @Id
  private Integer id;
  private String name;
  private double num;
}

But now when I compare I get this:

Diff:
* changes on com.FooB/1 :
  - 'name' changed from 'old' to 'new'

It's registering as a value change rather than a collection change. I want the diff to read like so:

Diff:
* changes on com.FooA/#fooB/1 :
  - 'fooB' collection changes :
    . 'name' changed from 'old' to 'new'

What am I doing wrong?

回答1:

Using Javers version 5.2.4:

public class FooA {
    private List<FooB> fooB;

    public FooA(List<FooB> fooB) {
        this.fooB = fooB;
    }
}

public class FooB {
    private Integer id;
    private String name;
    private double num;

    public FooB(Integer id, String name, double num) {
        this.id = id;
        this.name = name;
        this.num = num;
    }
}

void test() {
    FooA old = new FooA(Arrays.asList(new FooB(1, "old", 1.0)));
    FooA new1 = new FooA(Arrays.asList(new FooB(1, "new", 1.0)));

    Javers javers = JaversBuilder.javers()
            .withListCompareAlgorithm(LEVENSHTEIN_DISTANCE)
            .build();

    System.out.println(
            javers.compare(old, new1)
    );
}

method test returns:

Diff:
* changes on pl.javers.JaversTest$FooA/ :
  - 'fooB/0.name' changed from 'old' to 'new'

It is almost the same as you wanted.

FooA/fooB/0.name -> fooA has array fooB and first (index 0) name property has changed

来源：https://stackoverflow.com/questions/55031433/javers-comparing-list-in-order

标签

java

list

java-8

compare

javers