f32/f64 values in structured logs are treated as strings

[rukai]

How do you use Sentry?

Sentry SaaS (sentry.io)

SDK version

0.48.4

Steps to reproduce

let value: f32 = 1.0;
tracing::info!("hi", value)

Expected result

Value should show up as a float in the sentry web UI

Actual result

value does not show up as a float in the sentry web ui

Investigation

I can see here that tracing supports floats in its structured values:
https://docs.rs/tracing/latest/tracing/field/trait.Visit.html#method.record_f64

But sentry's implementation of Visit does not implement record_f64

sentry-rust/sentry-tracing/src/converters.rs

Line 158 in eb932e2

impl Visit for FieldVisitor {

[linear-code]

RUST-262

[szokeasaurusrex]

Hi @rukai, thank you for reporting this issue.

Unfortunately, the code snippet you provided does not compile for me; I get the following error:

error: argument never used
  --> src/main.rs:26:26
   |
26 |     tracing::info!("hi", value);
   |                    ----  ^^^^^ argument never used
   |                    |
   |                    formatting specifier missing
   |
help: format specifiers use curly braces, consider adding a format specifier
   |
26 |     tracing::info!("hi{}", value);
   |                       ++

Even with the compiler's suggested solution of adding the format specifier, I am not noticing any unexpected behavior. With that suggestion, the log looks like this in Sentry:

That output is formatted the same way that tracing formats it in the terminal:

2026-07-08T13:05:09.324159Z  INFO tracing_log_floats: hi1

---

Could you please clarify more precisely how I can reproduce the issue you are seeing? And, could you also clarify what you mean when you say that the value is "displaying as a string, not a float," because what you mean is not entirely clear.

[rukai]

Sorry, that was poor of me that it didn't even compile.

I am talking about structured logging:

fn main() {
    let value: f32 = 1.0;
    tracing::info!(value=value, "hi")
}

When filtering by structured logs in the sentry web app, it shows the type of structured value when typing in the field name.
My understanding is the type then impacts sorting behavior.
(the field has a different name here because I just grabbed the screenshot from our production application)

[szokeasaurusrex]

Thanks for the clarification, I was able to reproduce. Definitely seems like a bug or unexpected behavior at a minimum