JsonExtractBoolean

ComfyUI graphs like to be controlled by a single source of truth sitting at the top - a note, a config string, a TOML prompt file's exports block. The moment that source is JSON, you need a way to pull individual fields out of it, and that's the entire job of the JsonExtract* family in this pack. JsonExtractBoolean is the one that hands you a BOOLEAN you can wire into a toggle input: enable a hires-fix pass, switch a branch on, gate a LoRA, whatever your graph has converted to an input.

It's a small node and it's genuinely useful, because "read a flag out of a config" is otherwise a manual step you redo every run.

How it works

def extract(self, json_text: str, path: str, default: bool):
    r = json.loads(json_text)
    for key in path.split("."):
        if key not in r:
            return (default,)
        r = r[key]
    if isinstance(r, str):
        return (r == "True" or r == "true",)
    else:
        return (not not r,)

Three things fall out of that:

• path is dot-separated and walks dict keys, so hires.enabled looks inside {"hires": {"enabled": true}}. Lists are not indexed - there's no [0] syntax.
• A missing key returns default, which is the whole reason default exists as a required input. No exception, no red node.
• Strings get compared literally against "True" and "true". So "yes", "1", "TRUE" all read as False. Everything non-string falls through to Python truthiness: 0, "", [] and {} are False, anything else is True.

That last part matters in practice because JSON written by hand and JSON written by a tool look different. If a config value comes out inverted, print it and check whether it's the boolean true or the string "true".

Inputs and outputs

json_text - the blob, wired in from wherever your config lives (this pack's PromptDecode has a JSON Exports output that plugs in directly). path - the dotted route to the value. default - what you get when the path doesn't resolve. One BOOLEAN output.

Siblings do the same thing at other types: JsonExtractInt, JsonExtractFloat, JsonExtractString. Same three inputs, same dotted path, different output type.

Install

Manager search for the pack name, or:

cd ComfyUI/custom_nodes
git clone https://github.com/morino-kumasan/comfyui-toml-prompt

restart ComfyUI. No pip step - requirements.txt is empty, this is stdlib json plus ComfyUI. The pack's README still documents an SSH clone of its old comfyui-utils name; use the HTTPS URL above.

Where people get burned

Invalid JSON raises. The json.loads call is not guarded - only missing paths fall back to the default. A trailing comma or a stray smart quote and the node throws instead of quietly using your default. If a node that "should just return the default" is erroring, your JSON is malformed, not your path.

A path that silently diverges from your config. Rename a key in the TOML and this node keeps returning the default forever, with no warning. When a flag "isn't taking effect," check the path before anything else.