redis/redis-py · error · TypeError

prefix must be provided

Error message

prefix must be provided

What it means

Raised by IndexDefinition._append_prefix when the prefix argument is exactly None. The constructor default is an empty list ([]), so this only triggers when a caller explicitly passes None, which the library treats as a programming mistake rather than 'no prefix'. Pass an empty list to index all keys, or a list of key-prefix strings.

Source

Thrown at redis/commands/search/index_definition.py:48

        self._append_prefix(prefix)
        self._append_filter(filter)
        self._append_language(language_field, language)
        self._append_score(score_field, score)
        self._append_payload(payload_field)

    def _append_index_type(self, index_type):
        """Append `ON HASH` or `ON JSON` according to the enum."""
        if index_type is IndexType.HASH:
            self.args.extend(["ON", "HASH"])
        elif index_type is IndexType.JSON:
            self.args.extend(["ON", "JSON"])
        elif index_type is not None:
            raise RuntimeError(f"index_type must be one of {list(IndexType)}")

    def _append_prefix(self, prefix):
        """Append PREFIX."""
        if prefix is None:
            raise TypeError("prefix must be provided")
        if len(prefix) > 0:
            prefix = list_or_args(prefix, [])
            self.args.append("PREFIX")
            self.args.append(len(prefix))
            for p in prefix:
                self.args.append(p)

    def _append_filter(self, filter):
        """Append FILTER."""
        if filter is not None:
            self.args.append("FILTER")
            self.args.append(filter)

    def _append_language(self, language_field, language):
        """Append LANGUAGE_FIELD and LANGUAGE."""
        if language_field is not None:
            self.args.append("LANGUAGE_FIELD")
            self.args.append(language_field)

View on GitHub (pinned to da03cdc7e8)

Solutions

1. Pass an empty list for no prefix filtering: IndexDefinition(prefix=[]).
2. If the value may be None, coalesce it: IndexDefinition(prefix=prefix or []).
3. Provide the intended prefix list, e.g. IndexDefinition(prefix=['product:']).

Example fix

// before
IndexDefinition(prefix=config.get('prefix'))
// after
IndexDefinition(prefix=config.get('prefix') or [])

def safe_prefix(p):
    return p if p is not None else []

# usage: IndexDefinition(prefix=safe_prefix(raw_prefix))

def is_prefix_ok(p) -> bool:
    return p is not None and hasattr(p, '__len__')

try:
    IndexDefinition(prefix=raw)
except TypeError:
    IndexDefinition(prefix=[])

When it happens

Trigger: IndexDefinition(prefix=None) or forwarding a variable that is None, e.g. IndexDefinition(prefix=config.get('prefix')) when the key is absent and dict.get returns None.

Common situations: Loading prefix from optional config/env that yields None; refactoring a call site that previously omitted prefix and then someone added prefix=None explicitly believing it means 'no prefix'.

Related errors

• index_type must be one of {list(IndexType)}
• Did not receive a Filter object.
• Did not receive a SortByField.
• At least one tag must be specified
• collect fields must be '*' or a non-empty list of names

AI-assisted analysis of redis/redis-py@da03cdc7e8 (2026-08-04). Data as JSON: /data/errors/b6cc84a7d8c22622.json. Report an issue: GitHub.