I have model class:

@Entity 
public class Customer {
    @Id 
    @GeneratedValue(strategy = GenerationType.AUTO)
    public long id;
    public String name;
    public String phone;
    //...
}

Now there is an update operation in which I want to update the existing data. My code:

public void updateCustomer(Customer customer) {
    Customer existingCustomer = customerRepository.findById(customer.getId())
                                                  .orElse(null);

    /* Now here I want to update only fields which are not null            
       if(customer.getInfo() != null)
       existingCustomer.setInfo(customer.getInfo()); 
    */
    customerRepository.save(existingCustomer);
}

How to do this in an effective way as I can't check for each field and set it in my object.

CodePudding user response：

One possible solution would be to combine JsonNullable and MapStruct features as described in this very detailed article.

CodePudding user response：

I'm assuming that your fields are public as a shortcut for making the question straightforward.

I suggest you to create a special method in your entity that accepts a second entity and iterates over their fields.

e.g.

    class Customer {
        // one hundred fields here
        public void updateOnlyNonNulls(Customer customer){
            for (Field declaredField : Customer.class.getDeclaredFields()) {
                try {
                    Object o = declaredField.get(customer);
                    if(o!=null)
                        declaredField.set(this, o);
                } catch (IllegalAccessException e) {
                    throw new AssertionError("Should not happen");
                }
            }
        }
    }

Do not be reluctant to add rich behavior to your entities.