empty collection could be null an empty set indeed

[doanduyhai]

empty collection could be null an empty set indeed

[doanduyhai]

You mean that given a @NotNull annotation, Achilles should set an empty collection to an entity when reading null columns from Cassandra isn't it ?

[vladimirdolzhenko]

I suppose it is reasonable.

[doanduyhai]

Be aware that setting @NotNull will also trigger validation on the collection when you persist the entity (provided you activate Bean validation).

I prefer to keep the @NotNull annotation for Bean Validation and create another one to inject empty collections/maps when deserializing data from Cassandra. Maybe @EmptyCollectionIfNull or something similar (any suggestion for a better name is welcomed).

It is better to separate both concerns and do not mix them

[vladimirdolzhenko]

The simple case is : domain object has an empty set, the validation takes place on persist and it persists well - if I find a value, change any other value - I have to set empty collection instead of nulls - and all that null checks will be over the code.

[doanduyhai]

"if I find a value, change any other value - I have to set empty collection instead of nulls - and all that null checks will be over the code."

In this case, I can make @EmptyCollectionIfNull apply both on persist/update and on load

[doanduyhai]

Interestingly, @EmptyCollectionIfNull can be coded as a built-in interceptor that takes place before Bean Validation

[vladimirdolzhenko]

I don't like to introduce one more annotation while @NotNull in this case means the same

[doanduyhai]

Or I can make deserializing null into empty collections as default behavior in Achilles. This way, no need to introduce an extra annotation

[vladimirdolzhenko]

My point is

• default behavior in Achilles is null values for collections
• if there is a @NotNull or @EmptyCollectionIfNull provides empty collection (new HashSet<> neither Collections.emptySet() )

[doanduyhai]

Ok, I would go with @EmptyCollectionIfNull. @NotNull will force people to pull Bean Validation jar dependency even though they do not want to use Bean Validation

[doanduyhai]

I've just check, the default behavior of the Java Driver is to return an empty collection or map if the value coming from Cassandra is null: https://github.com/datastax/java-driver/blob/2.0/driver-core/src/main/java/com/datastax/driver/core/ArrayBackedRow.java#L254

Since Achilles gets value from the Java Driver, there is nothing to do indeed ...

I've written an IT to confirm it:

  @Test
    public void should_test_not_null_collections() throws Exception {
        //Given
        CompleteBean entity = CompleteBeanTestBuilder.builder().id(10L).name("name").buid();
        manager.persist(entity);

        //When
        final Row row = manager.getNativeSession().execute("SELECT * FROM CompleteBean WHERE id=?", 10L).one();

        //Then
        final List<String> friends = row.getList("friends", String.class);
        assertThat(friends).isNotNull().isEmpty();

        final Set<String> followers = row.getSet("followers", String.class);
        assertThat(followers).isNotNull().isEmpty();

        final Map<Integer, String> preferences = row.getMap("preferences", Integer.class, String.class);
        assertThat(preferences).isNotNull().isEmpty();
    }

This issue can be closed.

[vladimirdolzhenko]

I think the bug has to be reopened:

my code:
getPersistenceManager().typedQuery(MyEntity.class, "SELECT * from myentity;").get();

TypedQueryBuilder.get : 79
T entity = mapper.mapRowToEntityWithPrimaryKey(meta, row, propertiesMap, managed);

EntityMapper.mapRowToEntityWithPrimaryKey : 71
Object value = cqlRowInvoker.invokeOnRowForFields(row, pm);

RowMethodInvoker.invokeOnRowForFields : 41
if (row != null && !row.isNull(propertyName)) {

com.datastax.driver.core.ArrayBackedRow.isNull : 56
return isNull(metadata.getFirstIdx(name));

com.datastax.driver.core.ArrayBackedRow.isNull : 52
return data.get(i) == null;

based on the data it returns NULL -> therefore entity is NOT populated with non-null set/list/map

[doanduyhai]

You're right, the check in done in Achilles

On Tue, Apr 29, 2014 at 10:31 AM, Vladimir Dolzhenko <
[email protected]> wrote:

I think that the bug has to be reopened:

TypedQueryBuilder.get : 79
T entity = mapper.mapRowToEntityWithPrimaryKey(meta, row, propertiesMap,
managed);

EntityMapper.mapRowToEntityWithPrimaryKey : 71
Object value = cqlRowInvoker.invokeOnRowForFields(row, pm);

RowMethodInvoker.invokeOnRowForFields : 41
if (row != null && !row.isNull(propertyName)) {

com.datastax.driver.core.ArrayBackedRow.isNull : 56
return isNull(metadata.getFirstIdx(name));

com.datastax.driver.core.ArrayBackedRow.isNull : 52
return data.get(i) == null;

based on the data it returns NULL -> therefore entity is NOT populated
with non-null set/list/map

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Reply to this email directly or view it on GitHubhttps://github.com//issues/53#issuecomment-41652516
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[vladimirdolzhenko]

btw, I didn't find your IT in code - have you committed it ?

[doanduyhai]

Nope, I did not commit the IT since it was for checking only. But I'll definitely add new IT to cover the @EmptyCollectionIfNull case

[doanduyhai]

Done. Add unit and integration tests too