String Format

ComfyUI's string plumbing is the least-glamorous part of the graph and the one everyone ends up needing. String Format from the Diztraido pack is a template engine for strings: you write a template with {1}, {2} placeholders, set how many inputs you want, and it substitutes values from sockets that accept strings, ints, floats, or booleans. The interesting part is the extras: a {1?} placeholder deletes the whole line when that input is empty, and there's a real @if/@else/@endif conditional block system with comparison operators. It's the node you reach for when you're building a filename, an API payload, or a prompt that changes shape depending on what's actually connected.

The default template is literally File_{1}_teste_{2} - the author is Brazilian and it shows, but that's a fine starting point for "filename with a couple of variables" workflows.

How it works

The backend is a small template interpreter. Positional {1}…{16} substitute in order; the ? suffix ({1?}) is the clever bit - if that input is None, empty, or whitespace, the entire physical line containing it is removed, which is perfect for optional chunks like a style tag line. Numbers and booleans are preserved as values (a numeric 0 or false is not treated as empty). Whole-line @if {1} / @else / @endif blocks work with the same operators as inline expressions (==, !=, <, <=, >, >=, !, &&, ||, parentheses), nestable, and can contain raw JSON without escaping. A few structural niceties: literal JSON braces are fine as-is, {{ escapes a placeholder-looking sequence, and when an optional line or block is removed, trailing commas before } or ] get cleaned automatically so your generated JSON stays valid. Lines starting with # are dropped. The frontend extension adds/removes input sockets as you change input_count.

The inputs that matter

• template - the multiline template with placeholders and conditionals.
• input_count - 0 to 16, how many input_N sockets exist. Set this before wiring.
• single_line_output - normalize the output to a single line when on.

Optional input_1 … input_16 - wildcard sockets that accept any type.

Output: string (STRING), ready for a prompt encoder, filename prefix, or a Save Text node.

A quick example - this template:

portrait of {1}
@if {2}
  , in the style of {2}
@endif
@if {3}
  , {3}
@endif

with input_1 = "a woman", input_2 = "art deco", input_3 empty produces portrait of a woman, in the style of art deco - and if you later disconnect input_2, the middle line vanishes instead of leaving a dangling comma.

How to install

Part of Diztraido Nodes. ComfyUI Manager → search "Diztraido Nodes" → install diztraido-nodes → restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/jadervasque/ComyUI-Diztraido.git

Restart and it's under the Diztraido utils category. No dependencies or models.

Common issues

The usual stumbles: forgetting that input_count gates which sockets exist (the template can reference {5} all day, but if input_count is 2, there's no input_5 socket), and the difference between {1} and {1?} - use the plain form when you always want the value, the ? form when the line should disappear if empty. Also, single_line_output normalizes everything to one line; if you're building a multi-line prompt and toggle it by mistake, you'll wonder where your paragraphs went.