Unknown handler id issue

[SarkarSapna]

Getting unknow handler id issues when any select event or other event fire. How to resolve the issue

Error
Unknown handler id: C:.Users.labadmin.Desktop.sa...ServiceNow.set_assignment_group.f64511b3a5da324edfc9378e3b469bdc8e5463d909a2bd131a575e2af8d46e75 from event states {
states {
data: "{"show_servicenowdata": false, "filter_incident_data": {}, "assigned_to_list": ["Ab ", "Du", "Vin", "NOT ASSIGNED"], "assignment_group_options": [], "virtual_im_data": [{"id": "68397a6771c983a349d54aa4", "precedence_number": "1", "short_description": "Creating new ticket", "number": "INC0030459", "assigned_to": "NOT ASSIGNED", "reason": "This ticket is required immediate attention due to critical priority and state indicating it's new, with all deadlines being imminent and a very close response time indicating an urgent need for action.", "action": "Immediate attention required. Create a new ticket for further investigation and escalate the issue to the relevant team since the user has initiated this action."}, {"id": "68397a6871c983a349d54aa6", "precedence_number": "2", "short_description": "Password reset VIP user", "number": "INC", "assigned_to": "NOT ASSIGNED", "reason": "This ticket has a critical priority and also requires immediate action due to its status of being new and the urgency surrounding a VIP user's password reset.", "action": "Immediate action needed to reset the password for the VIP user. Assign this ticket to the support team directly for prompt resolution."},{"id": "683", "precedence_number": "2", "short_description": "Password reset", "number": "INC0", "assigned_to": "Du ", "reason": "This ticket comes second as it shows important urgency with a high priority and an imminent SLA, but it lacks the critical designation present in the first ticket.", "action": "Proceed with the password reset as per the user's comment. Confirm successful completion and inform the user. Ensure that documentation is updated reflecting the status of this incident."}], "virtual_im_filter": "", "assigned_group_selected": "", "assigned_to_selected": "", "work_notes_value": "", "additional_comments_value": "", "incident_state_data": "", "assigned_to_options": ""}"
}
}
handler_id: "C:.Users.labadmin.Desktop.sapna...ServiceNow.set_assignment_group.f64511b3a5da324edfc9378e3b469bdc8e5463d909a2bd131a575e2af8d46e75"
key {
}
bytes_value: "\n\nCmp2 group"
viewport_size {
width: 1280
height: 559
}
theme_settings {
prefers_dark_theme: false
theme_mode: THEME_MODE_LIGHT
}
Traceback
C:\Users\labadmin\Desktop\sa.venv\Lib\site-packages\mesop\server\server.py:225 | generate_data
for _ in result:
C:\Users\labadmin\Desktop\sa.venv\Lib\site-packages\mesop\runtime\context.py:374 | run_event_handler
raise MesopException(

My code
def data():

state = me.state(State)
with me.box(
    style=me.Style(
        padding=me.Padding.all(20),
        background=me.theme_var("surface-container-lowest"),
        border=me.Border.all(me.BorderSide(
            width="0.5px", color="#d3d3d3", style="solid")),
       
        box_shadow="0 4px 8px rgba(0, 0, 0, 0.1)"
    )
):
    me.text("Incident Details", type="headline-6")
    

    # Layout for two key-value pairs per row
    data_keys = list(state.filter_incident_data.keys()) // state.filter_incident_data contains object with key pair values
    for key in data_keys: # Iterate through each key individually
        value = state.filter_incident_data[key]
        # Each key-value pair gets its own row (wrapped in a box for consistent styling)
        with me.box(style=me.Style(margin=me.Margin(bottom=15))):
            render_form_field(key, value, state)


    
    me.button("Save", on_click=on_save_incident, style=me.Style(margin=me.Margin(top=20)))

Helper function to render form fields based on key

def render_form_field(key: str, value, state: State):
with me.box(style=me.Style(flex_grow=1)): # Allows fields to take equal space
# Check if the current value is a dictionary (nested object)
if isinstance(value, dict):
# If it's a nested object, display its own key and then iterate through its contents
with me.box(style=me.Style(margin=me.Margin(bottom=10))):
me.text(f"{key.capitalize()} : ", style=me.Style(font_weight="medium",margin=me.Margin(bottom=10)))
with me.box(style=me.Style(margin=me.Margin(left=20))): # Indent nested fields
for sub_key, sub_value in value.items():
# Recursively call render_form_field for nested key-value pairs
# or display them as plain text if no specific component needed
with me.box(style=me.Style(display="flex", flex_direction="row", align_items="baseline", margin=me.Margin(bottom=10))):
me.text(f"{sub_key.capitalize()} : ", style=me.Style(font_weight="medium"))
me.text(str(sub_value))
if key == "assignment_group":
me.text(f"{key.capitalize()} : ", style=me.Style(font_weight="medium", margin=me.Margin(bottom=5)))
me.select(

            options=[me.SelectOption(label=opt, value=opt) for opt in state.assignment_group_options],
            value=state.assigned_group_selected, # Default value
            on_selection_change=set_assignment_group,
            style=me.Style(width="60%") # Ensure it takes full width of its box
        )

Event handlers for updating state

def set_assignment_group(e: me.SelectSelectionChangeEvent):
state = me.state(State)
state.assigned_group_selected = e.value
print(f"Assignment group changed to: {e.value}") # For debugging

[richard-to]

I'm not too sure what's going on. But my guess right now is that the handler ID is changing for some reason. This can happen some times with dynamically generated form fields. In this case, the way you're defining the function seems fine since it should be static.

Is there a case where this part may not get rendered:

if key == "assignment_group":
me.text(f"{key.capitalize()} : ", style=me.Style(font_weight="medium", margin=me.Margin(bottom=5)))
me.select(

            options=[me.SelectOption(label=opt, value=opt) for opt in state.assignment_group_options],
            value=state.assigned_group_selected, # Default value
            on_selection_change=set_assignment_group,
            style=me.Style(width="60%") # Ensure it takes full width of its box
        )

Because if it's possible for it not to be rendered, there could be case where the handler id could get removed. Purely a guess though.

[SarkarSapna]

here the case is i am getting data from somewhere through api i am showing the data based on its availability. Can you please help me with some solution.

[richard-to]

Can you try to reproduce the issue with a simple example Mesop app? If you can post the code for that, then I can try to help debug it. Otherwise it's a bit hard for me to help. Unfortunately I don't see anything obviously wrong with your snippets.