IndexDefinition Prefix Footgun

[coldham10]

Discovered a very confusing footgun during a recent refactor with the peculiar syntax of RediSearch IndexDefinition and insufficient type checking.
Consider the following, sensible-looking code:

my_prefix = "MY:INDEXABLE:KEY:"
index_key = my_prefix + "index"

defn = IndexDefinition(prefix=my_prefix, index_type=IndexType.HASH)
redis_client.ft(index_key).create_index(my_fields, definition=defn)

What would we expect this to do?
Create an index of hashes prefixed by my_prefix ? No.
Error, because the arg prefix= expects an iterable? No..
Index every single hash prefixed by {"M", "Y", ":", "I", "N", "D", "E", "X", "A", "B", "L", "K"} ? It seems this is actually what happens.

Might I suggest IndexDefinition takes a keyword argument of prefixes= to indicate that it expects an iterable?

Or, in index_definition.py:

    def _append_prefix(self, prefix):
        """Append PREFIX."""
        if len(prefix) > 0:
            self.args.append("PREFIX")
            self.args.append(len(prefix))
            for p in prefix:
                self.args.append(p)

A quick raise RuntimeError if prefix is a string

Thanks for considering!

[petyaslavova]

Hi @coldham10, thanks for raising this! We’ll take a look and get back to you shortly.