List Keys

Hand a dict to listKeys and you get back its keys as a list. Hand it a list or tuple and you get back the indices. It's a two-line Python utility (list(obj.keys())) that lives in ovum/loop because it's most useful when you're doing structured iteration over dictionaries - which ComfyUI's graph makes surprisingly awkward without a node that converts a dict's keys into a fan-out-able list.

The type is * on both sides, so it's deliberately loose: any object in, a list out. What it does depends on what you give it, straight from the source:

• dict → list(dict.keys()) - the actual keys, in insertion order.
• list or tuple → list(range(len(obj))) - positions 0, 1, 2, ... up to the length.
• anything else → an empty list, gracefully, rather than crashing.

When this actually helps

ComfyUI's native data types are tensors and strings; Python dicts usually show up when you're working with embedded workflow metadata, image-ex context objects, or API-style payloads. If a node hands you a dict and you want to iterate over its entries - say, every key in a metadata blob - listKeys gives you the list to loop over, and the pack's listValues gives you the matching values in the same order. The classic pairing is listKeys + Get by Index inside a loop: for each key, pull the value.

It also behaves sensibly as a list-length helper in a pinch: feed it a list, get back [0..n-1], and the length is implied. (There's a dedicated GetListLength in the same category if you want the count explicitly.)

The pairing that matters

listKeys and listValues are two halves of the same trick, both in ovum/loop:

• listKeys(obj) → ["prompt", "workflow", "seed"] (or [0, 1, 2] for a list).
• listValues(obj) → the values in the same order.

Use them together when you need to zip keys and values through two parallel lists, or drive a loop over a dict without hand-typing the keys.

Install

Part of comfy-ovum, so one install covers it:

cd ComfyUI/custom_nodes
git clone https://github.com/sfinktah/comfy-ovum

or search comfy-ovum in ComfyUI Manager and restart. No models, no keys.

Gotchas

The output is a single * socket holding a list - if your downstream node expects a Comfy batch-style list of items rather than one list object, you may need a passthrough/cast node from this same pack to adjust how the list is treated. And remember it's not a "length" node: feeding it a string returns an empty list, not an error, which can silently look like "no keys" if you wired it wrong.