UserMessage not appearing in the app

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1

Which tool versions are you using?

SDK: v14.21.0
Platform: v25.06.4
Python: v3.11
Isolation mode: venv

Current Behavior

I’m trying to show the user a warning, which shouldn’t forbid continuing the following steps.
Violations work as intended, but UserMessage.warning (/.info/.success) aren’t working. The message only appears in the terminal (when in dev mode), and not at all in the publication state.

Here’s a shortened version of what I’m attempting to do:

import viktor as vkt


def check_step1(params, **kwargs):
    """Warn if the toggle is On"""
    violations = []
    if params.step1.bool:
        msg = "Toggle shouldn't be On"

        # Record the violation
        if True:  # no impact on the user messages
            violation = vkt.InputViolation(msg, fields=["step1.bool"])
            print(msg)
            violations.append(violation)

        # User messages - NOT WORKING
        vkt.UserMessage.info(f"INFO: {msg}")
        vkt.UserMessage.warning(f"WARNING: {msg}")
        vkt.UserMessage.success(f"SUCCESS: {msg}")

    # Show the violations
    if violations:
        msgs = ". ".join([f"{v.message}. Fields: {v.fields}" for v in violations])
        raise vkt.UserError(f"ERROR! {msgs}", input_violations=violations)


class Parametrization(vkt.Parametrization):
    step1 = vkt.Step("Step1", on_next=check_step1)
    step1.bool = vkt.BooleanField("Toggle", default=False)

    step2 = vkt.Step("Step2")
    step2.txt = vkt.Text("Welcome to step 2")


class Controller(vkt.Controller):
    parametrization = Parametrization

Context

I want to use user messages because I have a case where a value x should be smaller than x_warn, and must be smaller than x_max (both bounds depend on multiple parameters and are calculated on_next). I therefore want to warn the user if they input x > x_warn, and forbid them from inputting x > x_max.

2

User messages are retrieved on a polling interval. My hypothesis is that the check_step1 method returns before that time. I think you are right to expect to see the message, so this is something we need to look into. Thanks for reporting.

1 Like
3

Thanks for your message Raoul.

Am I perhaps misunderstanding how user messages should be used? Should they be used at another stage than on next?

4

Hi Remi,

No you are not misunderstanding how they should be used. I’ll try to explain what the current behavior is; lets say the user messages are polled by the FE with a 1 second interval. If your on_next method returns within that second the message won’t be visible in the UI. I understand that this behavior is unexpected, so I think it is something that should be addressed on our side.