Spring boot + Jackson. How to serialize collections which have null value as empty lists?

Question

In my entity I have:

private Set<Account> accounts;

Now it is being serialized like this:

"accounts": null

I need to change it to

"accounts": []

I have many (150+) entities which have this problem - how can configure jackson mapper to achieve this?

Yes, that will definitely help but I can't do this do to reasons which I can't change unfortunately. — Don_Quijote, Dec 05 '17 at 13:44
See this question: https://stackoverflow.com/questions/35432133/jackson-serialize-non-initialized-collection-field-as-empty — Steven M. Wurster, Dec 05 '17 at 13:55
Yes, thank you, I'm aware about this. But I have about 150+ entity classes so writing JsonSerializer implementation for each will be not best solution inmy case. — Don_Quijote, Dec 05 '17 at 13:57
There does not appear to be a setting in Jackson for this, so you're either going to have to use empty collections or write a serializer. Using a serializer may be possible if your entity classes can inherit from a single parent. — Steven M. Wurster, Dec 05 '17 at 14:10

score 0 · Answer 1 · answered Dec 05 '17 at 13:48

0

You could remove the "accounts" completely from the json annotating your pojo with:

@JsonInclude(JsonInclude.Include.NON_NULL)

maybe this helps

answered Dec 05 '17 at 13:48

andgalf

I need to keep accounts in my json, need to have it as [] if it is null. – Don_Quijote Dec 05 '17 at 13:53

David Billings · Accepted Answer · 2017-12-05T14:12:33.027

0

I think declaring your set like this will work...

private Set<Account> accounts = new HashSet<>();

It's then an empty set when marshalling and not null.

edited Dec 05 '17 at 14:12

answered Dec 05 '17 at 14:09

David Billings

This is what we do where I currently work. Much easier, and we just avoid passing null to the setter for the variable. – Steven M. Wurster Dec 05 '17 at 14:11
That should work. It can also be done in the constructor. – Marc Tarin Dec 05 '17 at 14:12

2 Answers2