Concatenate With Prefix

Every string concatenation node lets you pick a delimiter. This one adds the thing most of them forget: a prefix that gets applied to every piece, with a built-in %n% counter so each segment can be numbered. The author's framing is fair - "most concatenation nodes only let you specify a delimiter. Why not a prefix as well?" - and the dynamic counter is the part you didn't know you wanted until you're building a labeled prompt block.

Why you'd reach for it

The killer use case is metadata and sectioned prompts. Instead of getting "artist_a, artist_b, artist_c" you get "1: artist_a, 2: artist_b, 3: artist_c" - a numbered, prefixed block that reads like a real list. It also shines when you're assembling a prompt from multiple sources and want a consistent label on each piece, like "style: watercolor" repeated per segment. If you've ever wanted to slap a category onto every chunk of a concatenated string without doing it by hand, this is the node.

How it works

It takes up to eight optional string_N inputs, drops the empty ones, and joins the survivors in order with your delimiter. The prefix is applied to each segment before joining, and any %n% inside the prefix is replaced with the segment's position (1-based). So with prefix "%n%: " and delimiter ", ", two strings become "1: first, 2: second". Because the prefix is a normal string field, you can also leave out %n% entirely and just use it as a constant label - the counter is an option, not a requirement.

The inputs that matter

• delimiter (STRING, default ", ") - what goes between segments.
• prefix (STRING, default "%n%: ") - what leads each segment; %n% becomes the counter.
• string_1 through string_8 (STRING, all optional) - the pieces to join. Empty inputs are skipped, so you can wire all eight and leave some unused.
• STRING - the joined result.

Installing it

It ships in comfyui-lopi999-nodes:

cd ComfyUI/custom_nodes
git clone https://github.com/LaVie024/comfyui-lopi999-nodes

Restart ComfyUI, or use ComfyUI Manager and search "comfyui-lopi999-nodes." No models, no dependencies.

Common issues

The ordering is by input number, not by wiring order - string_2 always follows string_1 regardless of where you dragged the wires, which is what you want but worth knowing when a graph looks tangled. The counter is 1-based, so the first segment is 1, and only segments that survive the empty-filter get numbered; a missing string_2 means string_3 becomes 2. And the %n% replacement only works in the prefix field - the delimiter is left literally alone.