@JsonCreator with unknown fallback setter: do not throw error if FAIL_ON_UNKNOWN_PROPERTIES is false

[fromi]

Hi, I am currently using @JsonCreator to control object creation, combined with "readerForUpdating" to control object updates.
I have a property that can be created, but not updated. Therefore, it exists as an argument of my constructor, but there is not setter method.

I would like to ignore the property during update. However, I get this error:
No fallback setter/field defined: can not use creator property for ....

The culprit is CreatorProperty L192, with a nice comment:

        /* Hmmmh. Should we return quietly (NOP), or error?
         * Perhaps better to throw an exception, since it's generally an error.
         */

Actually, I would like an exception only if my mapper is configured to FAIL_ON_UNKNOWN_PROPERTIES. Am I correct?

Thanks for the great work by the way!

[cowtowncoder]

Thank you!

Interesting question here. I think your suggestion is good, to see if FAIL_ON_UNKNOWN_PROPERTIES is set; exception message should then reflect this as well.
So I think this is a reasonable RFE.

[cowtowncoder]

Finally looking into this, I think I misunderstood this, assuming there was a failure even without attempt to set a value.

However: in case of a known property (due to @JsonCreator), not having a setter, I think an exception seems reasonable: property is not unknown but there's just no way to assign it.

One possible remedy would be to use @JsonAnySetter in such case. I will actually create a separate RFE for this.

[cowtowncoder]

Re-created as #1401.

[fromi]

Hi, sorry for this late reply : I would like you to reconsider this issue.

I have an object with an immutable property. Some other properties are mutable. My immutable property is exposed to my front-end. The front-end code contains a form to update de mutable properties, and displays the immutable property. By convenience and code simplicity, I do not want to copy / remove the immutable property when I send my update request, therefore the immutable property is part of the request (but unchanged).
On the back-end side, for security reasons I do not want any setter for the property. However, this property is set, once, when the object is created.

Therefore, I think it a reasonable use case to have a property defined in a JsonCreator, provided inside a readerForUpdating request, but ignored by having no setter.

On the other hand, if you do not throw any exception, the only drawback is that the developer will need to analyse why the property was not updated. I think it is quite easy to find that a setter is missing.

Best regards,
Romain