Mastering Spring 5.0

Unit test

The findById() method can be used to query using the primary key. The following snippet shows an example:

    @Test    public void findOne() {      Optional<Todo> todo = todoRepository.findById(101L);      assertEquals("Todo Desc 1", todo.get().getDescription());    }

Optional represents a container object for an object that can be null. Some of the important methods in Optional are listed below:

• isPresent(): Check if Optional contains a non-null value.
• orElse(): Default value if the object contained is null.
• ifPresent(): Code in ifPresent is executed if the object contained is not null.
• get(): To retrieve the contained object.

The existsById() method can be used to check whether an entity with the given ID exists. The following example shows how ...