python data_error ai_generated partial

pydantic_core._pydantic_core.ValidationError: 1 validation error for Node children.0.parent Recursion error - cyclic reference detected [type=recursion_loop]

ID: python/pydantic-recursion-loop-detected

Also available as: JSON · Markdown · 中文
80%Fix Rate
83%Confidence
0Evidence
2024-08-09First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
2.x active — — —

Root Cause

The input data contains a cyclic reference (e.g. an object referencing itself), which Pydantic detects while validating a recursive model.

generic

中文

输入数据包含循环引用（例如对象引用自身），Pydantic 在验证递归模型时检测到该循环。

Workarounds

  1. 90% success 
    def strip_parent(node):
    node.pop('parent', None)
    for c in node.get('children', []):
        strip_parent(c)
    return node
Node.model_validate(strip_parent(data))
  2. 80% success 
    from pydantic import BaseModel

class Node(BaseModel):
    name: str
    children: list['Node'] = []

Node.model_rebuild()  # avoid modeling parent back-references

Dead Ends

Common approaches that don't work:

  1. 85% fail

    The cycle is in the data itself, not stack depth. It will still be detected and may crash the interpreter.

  2. 70% fail

    Loses the schema definition and breaks legitimate nested validation for non-cyclic inputs.