Max Toball
a3343e169a
ComfyUI has two things that both get called a list, and the difference is the whole reason this node exists. A *list output* -- a socket flagged OUTPUT_IS_LIST, which is what the built-in Create List produces -- is never delivered to downstream nodes: the executor runs them once per item and collects the results. A node only receives the list whole if it declares INPUT_IS_LIST. So a generic "index into any input" node that omits INPUT_IS_LIST is invoked once per element and returns each in turn. From the graph that looks like the index being ignored, which is a difficult thing to debug, because the node is working exactly as written on one item at a time, having never seen a list. This declares INPUT_IS_LIST and returns a single item. The consequence is that every input arrives wrapped, index included -- a widget set to 3 shows up as [3] -- so unwrapping is the other half of the job. The index widget carries control_after_generate, so setting it to increment walks one step per queued job: define the prompts once, queue N runs, get one prompt each. wrap mode lets you queue more jobs than you have items.
Simple List Picker
A ComfyUI node that takes a list and an index and returns the item at that index.
That is the whole node. It exists because the obvious way to write it is subtly wrong, and the wrong version fails in a way that looks like the index being ignored.
Install
git clone https://github.com/jmtoball/comfyui-simple-list-picker.git
into ComfyUI/custom_nodes/ and restart. No dependencies.
Use
Create List ──list──▶ Simple List Picker ──item──▶ (anything)
Primitive Int ─index──▶
| input | |
|---|---|
items |
Any list output — Create List, or anything with OUTPUT_IS_LIST |
index |
Negative counts from the end, as in Python |
mode |
wrap (default), clamp, or error when the index is out of range |
| output | |
|---|---|
item |
The value at that index, of whatever type went in |
resolved_index |
Where the index actually landed after wrap/clamp |
count |
How many items the list held |
One item per queued job
The index widget carries control_after_generate. Set it to increment
and it advances once per queued run, exactly as a seed does:
- Put your prompts in a
Create List. - Wire
Simple List Pickerbetween it and your text input. - Set
indexto0and its control toincrement. - Queue with a batch count of N.
Each job takes the next prompt. With mode: wrap you can queue more jobs than
you have prompts and it cycles.
Two things worth knowing: the index is a counter, not a queue, so nothing is consumed and re-running a job repeats its prompt; and the counter keeps climbing between sessions, so reset it by hand when you want to start over.
Why this needs to be its own node
ComfyUI has two different things that both get called a list:
- a list output — a socket flagged
OUTPUT_IS_LIST, which is whatCreate Listproduces. Downstream nodes never receive the list. The executor runs them once per item and collects the results. - a Python list received whole, which only happens when the receiving node
declares
INPUT_IS_LIST = True.
A generic "index into any input" node that does not declare INPUT_IS_LIST is
therefore invoked once per element and returns each of them in turn. From the
graph it looks as though the index is being ignored — the node is working
exactly as written, on one item at a time, having never seen a list.
This node declares INPUT_IS_LIST, so it receives every item and returns one.
The consequence is that all its inputs arrive wrapped, index included: a
widget set to 3 shows up as [3]. Unwrapping those is the other half of the
job, and getting it wrong turns the index into a list and the arithmetic into
something else.
Development
pip install pytest ruff
ruff check .
pytest tests
CI runs both on Python 3.10, 3.11 and 3.12.
License
MIT