Style from JSON file

If you came from Automatic1111, you remember styles - a dropdown of named prompt templates (Anime, Cinematic, Watercolor) that wrapped your text in boilerplate. ComfyUI has no built-in equivalent, so Style from JSON file (RF_JsonStyleLoader) builds one: a dropdown populated from JSON files, where each style is a prompt template with a placeholder for your actual prompt. Pick a style, type your subject, and it spits out a positive and negative prompt ready for the CLIP encoders.

It's a genuinely useful idea that ships with zero example data. The pack clones with no styles bundled, so the dropdown starts empty until you add your own JSON - which is the first thing that confuses people. There's also a quirk in how the placeholder works, so let's walk through it properly.

How it works

The node scans its own directory (custom_nodes/comfyui-rf-nodes/nodes/Json/) for .json files at load time. Each file is expected to be a list of objects with three keys: name, prompt, and negative_prompt. All styles across all files get merged into one dropdown, with duplicate names suffixed (_1, _2).

Each style's prompt is a template, e.g.:

[
  {
    "name": "Watercolor",
    "prompt": "watercolor of {prompt}, soft washes, paper texture",
    "negative_prompt": "oil paint, {negative_prompt}, harsh edges"
  }
]

The prompt input (default "{prompt}") is the search token inside the template, and the optional positive input is the real text that replaces it. So if positive is "a red fox", you get watercolor of a red fox, soft washes, paper texture. Same story for negative_prompt and negative. If a template's prompt field is empty, your positive text passes through untouched.

The inputs that matter

• style - the dropdown, populated from your JSON files. If it's empty, add a properly-formatted JSON file and restart.
• prompt / negative_prompt - the placeholder tokens (defaults {prompt} / {negative_prompt}). Only change these if your templates use different tokens.
• positive / negative - optional: your actual prompt text, usually wired from a text node. If left empty, the template's own text is what comes out.

Outputs: positive and negative STRINGs, straight into two CLIPTextEncode nodes.

The gotchas

• Validation is strict. Every item must have all three keys - name, prompt, and negative_prompt - or the whole file is rejected with a console warning and loaded as nothing. One missing key kills the file.
• Changes need a restart. Styles are read when the node is defined, not per-run. Edit the JSON, restart ComfyUI (or at least reload) before the dropdown updates.
• It reads only its own folder. The JSON has to live in nodes/Json/ inside the pack, not anywhere convenient. That's a design choice, and it's the thing you'll most likely trip over.

Installing RF Nodes

No dependencies, no models to download. Via ComfyUI Manager search "RF Nodes", or:

cd ComfyUI/custom_nodes
git clone https://github.com/foxtrot-roger/comfyui-rf-nodes

Restart ComfyUI. The node is under RF in the menu. Then drop your style JSON into custom_nodes/comfyui-rf-nodes/nodes/Json/ and restart again.