correctly handle backend rx.Field default values

[adhami3310]

fixes #5829

[codspeed-hq]

CodSpeed Performance Report

Merging #5833 will not alter performance

_{Comparing correctly-handle-backend-rx.Field-default-values (2fe887a) with main (e2105fe)}

Summary

✅ 8 untouched

[greptile-apps]

Greptile Overview

Summary

Fixed a bug where backend-only variables defined with rx.Field were storing the Field object itself instead of the actual default value, preventing method calls like .append() on mutable default values.

• Modified backend variable processing to extract default values from Field objects using value.default_value()
• Applied fix in both class initialization (new_backend_vars) and the _get_var_default method
• Ensures backend variables with Field definitions behave consistently with regular state variables

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The fix is targeted, addresses a specific bug with a clear root cause, uses existing APIs correctly, and maintains backward compatibility
• No files require special attention

Important Files Changed

File Analysis

Filename	Score	Overview
reflex/state.py	5/5	Fixed backend Field handling to extract default values instead of storing Field objects

Sequence Diagram

sequenceDiagram
    participant User as User Code
    participant State as BaseState
    participant Field as rx.Field
    participant BackendVars as backend_vars

    Note over User: _list_1: rx.Field[list[int]] = rx.field([1])
    
    User->>State: Class initialization
    State->>State: Process backend variables
    
    alt Before Fix
        State->>BackendVars: Store Field object directly
        Note over BackendVars: backend_vars['_list_1'] = Field object
        User->>BackendVars: self._list_1.append(1)
        BackendVars-->>User: AttributeError: Field has no append()
    else After Fix
        State->>Field: Check if isinstance(value, Field)
        Field->>State: True
        State->>Field: value.default_value()
        Field->>State: [1] (actual list)
        State->>BackendVars: Store actual default value
        Note over BackendVars: backend_vars['_list_1'] = [1]
        User->>BackendVars: self._list_1.append(1)
        BackendVars-->>User: Success: [1, 1]
    end

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[benedikt-bartscher]

Closes #5629 ?

[adhami3310]

Closes #5629 ?

yes!