ScrapeGraphAI/Scrapegraph-ai · error · ValueError

Error evaluating condition

Error message

Error evaluating condition '{condition}' in {self.node_name}: {e}

What it means

ConditionalNode._evaluate_condition uses asteval to safely evaluate the configured condition expression against the state; any exception during evaluation (unknown state variable, type error, unsupported operator, bad syntax) is wrapped in this ValueError that includes the node name and original error.

Solutions

1. Read the embedded '{e}' message to identify the underlying eval failure
2. Guard the condition against missing/None values, e.g. "parsed_docs is not None and len(parsed_docs) > 0"
3. Keep conditions to simple comparisons/logic supported by asteval (no imports, comprehensions, or complex attribute chains)
4. Test the condition string with the actual state dict in isolation

Example fix

# before
condition = "len(parsed_docs) > 0"
# after
condition = "parsed_docs is not None and len(parsed_docs) > 0"

# dry-run the condition against a sample state before deploying
from asteval import Interpreter
interp = Interpreter()
interp.symtable.update(sample_state)
assert interp(condition_expr) is not None or True  # smoke test

try:
    nxt = node.execute(state)
except ValueError as e:
    if 'Error evaluating condition' in str(e):
        logger.warning('condition failed; defaulting to false branch')
        nxt = node.false_node_name
    else:
        raise

When it happens

Trigger: A condition referencing a state key that is absent (NameError in eval), comparing incompatible types (e.g. 'len(parsed_docs) > "3"'), or using Python features asteval does not support (comprehensions, attribute access restrictions).

Common situations: Writing conditions against state keys that may be None on some paths; conditions that assume a type (list/int) the state doesn't hold for a given run; asteval's restricted eval rejecting a valid-Python expression.

Related errors

• ConditionalNode's next nodes are not set properly.
• You need to provide key_name inside the node config
• Adjacent state keys found without an operator between them.
• Conditional Node returned a node name
• ConditionalNode ' ' must have exactly two outgoing edges.

AI-assisted analysis of ScrapeGraphAI/Scrapegraph-ai@532dfffbf6 (2026-08-28). Data as JSON: /api/errors/b03c80729cdb6863. Report an issue: GitHub.

Appendix: source

Thrown at scrapegraphai/nodes/conditional_node.py:110

            condition (str): The condition expression to evaluate.

        Returns:
            bool: The result of the condition evaluation.
        """
        # Combine state and allowed functions for evaluation context
        eval_globals = self.eval_instance.functions.copy()
        eval_globals.update(state)

        try:
            result = simple_eval(
                condition,
                names=eval_globals,
                functions=self.eval_instance.functions,
                operators=self.eval_instance.operators,
            )
            return bool(result)
        except Exception as e:
            raise ValueError(
                f"Error evaluating condition '{condition}' in {self.node_name}: {e}"
            )

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