Support for saving of Null values for a property [DATAMONGO-1107]

[spring-projects-issues]

Alexej Kubarev opened DATAMONGO-1107 and commented

Currently it is not possible to save null-values for properties of an entity.
For example if trying to save an object Person that looks like below:

@Data
class Person {
    @Id
    private ObjectId id;
    private ObjectId parentId;
    private String name;
}

With only name set, it's natural that id is auto-created later, but in some cases it's desired to save parentId: null explicitly.
Today, saving this object would result in

{
   _id: ObjectId("......."),
   _class: "....Person",
   name: "some name"
}

I can understand the reasoning as Java does not really differentiate between null and undefined but this may cause problems in interoperability between different systems that work on the same data (i know, opening a Pandora's Box here).

If a system that created a person object in a DB was using another language or native driver, it would be possible to create entries with explicit parentId property set to null. If our system, however can also create Person, then we would never be able to achieve this simple with a MongoRepository.save(Entity s); method. So on both system we would have to query for something like findByParentIdNotExistsOrIsNull().

Generally todays behavior seems appropriate, but it would be helpful if we can have some way of saying that this value is nullable and thus should be explicitly saves as null. Maybe a @Nullable annotation on a field?.

It was also pointed out that it's possible to work around this by having an event listener for the AfterConvertEvent and explicitly set this value to null if needed on the entity as MongoDB driver supports saving null values

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Affects: 1.6.1 (Evans SR1)

Attachments:

• image-2019-04-09-21-37-11-690.png (49.16 kB)

5 votes, 5 watchers

[spring-projects-issues]

dit commented

this is really a bug and should be solved...

[spring-projects-issues]

Yura Nosenko commented

Hi, Oliver! IS anyone looking into this issue right now?

[spring-projects-issues]

Yura Nosenko commented

I would be happy to help if we discuss a possible solution

[spring-projects-issues]

Nilesh Akhade commented

We can also add a property if we want all our fields to be handled this way.

spring.data.mongodb.persist-null-fields=true

[spring-projects-issues]

Prateek commented

@Nikhil Akhade - I don't see  spring.data.mongodb.persist-null-fields=true option showing in my spring boot application.properties. Question : https://stackoverflow.com/questions/55596980/spring-data-mongo-doesnt-persist-field-value-as-null#

[spring-projects-issues]

Nilesh Akhade commented

Hey Prateek, assuming you mean @Nilesh Akhade.
This feature is not yet available with spring mongo data. I have suggested the property in my comment

[christophstrobl]

Resolved by #3407