python runtime_error ai_generated true

jinja2.exceptions.UndefinedError: 'user' is undefined

ID: python/jinja2-undefinederror-user-undefined

Also available as: JSON · Markdown · 中文
80%Fix Rate
90%Confidence
0Evidence
2024-03-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.x active — — —

Root Cause

A Jinja2 template references a variable that was not passed to the render context or is None.

generic

中文

Jinja2 模板引用了未传递给渲染上下文或为 None 的变量。

Workarounds

  1. 95% success 
    return render_template('index.html', user=current_user)
  2. 85% success 
    {% if user is defined %}{{ user.name }}{% endif %}

Dead Ends

Common approaches that don't work:

  1. 60% fail

    The default filter only works if the variable is undefined; if user is None, it still prints 'None'.

  2. 50% fail

    This silences the error but may lead to empty output and hides real bugs.