1910809 - Object metric: document (and possibly improve) behavior of null values

Status: RESOLVED FIXED

(Data Platform and Tools :: Glean: SDK, enhancement, P2)

Description

[Alex Franchuk [:afranchuk]]

Since null values aren't valid (as far as I know, though maybe they can be set as arrays or objects?), it'd be great if Glean allowed setString JSON objects to contain nulls and automatically ignore/remove them where appropriate (e.g. for an object where a key maps to null, the key will be removed). Right now, nulls seem to result in the metric not being set.

Whether the behavior changes or not, it'd be helpful to document it explicitly.

Comment 1

[Jan-Erik Rediger [:janerik] (Away 2026-04-02 - 2026-04-10)]

I actually think this is already the case for the Rust API; and for the JavaScript API too.
Are you running into trouble from Kotlin?

I'll take a look, at a test and better docs.

Comment 2

[Alex Franchuk [:afranchuk]]

I'm having trouble in Rust.

Comment 3

[Jan-Erik Rediger [:janerik] (Away 2026-04-02 - 2026-04-10)]

Oh. Ok, I take a look.

Comment 4

[Jan-Erik Rediger [:janerik] (Away 2026-04-02 - 2026-04-10)]

Can you show what code is going wrong? Because I currently cannot reproduce that.

Comment 5

[Alex Franchuk [:afranchuk]]

https://phabricator.services.mozilla.com/D218215

If you comment out the call to remove_nulls in this patch, a test will fail with the metric being unset (run mach rusttests).

Comment 6

[Jan-Erik Rediger [:janerik] (Away 2026-04-02 - 2026-04-10)]

I can reproduce that now, I'll look into it.

Comment 7

[Jan-Erik Rediger [:janerik] (Away 2026-04-02 - 2026-04-10)]

Attachment: [mozilla/glean_parser] Bug 1910809 - Object metric (Rust): Use vec helper function to deserialize empty vec from null (#742)

Comment 8

[BMO Github Automation]

Attachment: [mozilla/glean] Bug 1910809 - Rust: Test an object metric with null values (#2921)

Comment 9

[Jan-Erik Rediger [:janerik] (Away 2026-04-02 - 2026-04-10)]

badboy merged PR [mozilla/glean_parser]: Bug 1910809 - Object metric (Rust): Use vec helper function to deserialize empty vec from null (#742) in f554043.

Comment 10

[Jan-Erik Rediger [:janerik] (Away 2026-04-02 - 2026-04-10)]

badboy merged PR [mozilla/glean]: Bug 1910809 - Rust: Test an object metric with null values (#2921) in a18cadc.