Validate Dict [OLD]

StringConstructorValidateKeys is the old class ID for the Validate Dict node in Lex-DRL's String Constructor pack - the one the author kept around after the v3.x rename so pre-existing workflows still open. It's flagged deprecated and sits in the String Constructor/_old category. If you're building anything new, use the current "Validate Dict" node instead; this one only matters because your older graphs reference it by name. The behavior is identical.

Which is to say: it checks that every key in your dictionary is a name the String Formatter can actually format, and passes the dictionary through untouched. One optional dict input, one dict output, no settings. Keys must be non-empty strings using only ASCII letters, digits, and underscores, without a leading digit - those become Python str.format() keyword arguments, so bad-name or 1stChunk fail the check while bad_name and chunk1 pass. If anything's wrong it raises one grouped error message that lists the offending keys and the reason for each, so you see exactly what to fix.

It's optional plumbing, honestly. The String Formatter itself warns on bad keys when it formats, but this node's value is catching a bad dictionary early - right after the keys are set, in the author's words - before a whole branch of nodes has built on top of it. That's most useful when your dictionary was assembled by a node from another pack that doesn't enforce these naming rules.

Install

ComfyUI Manager → search "String Constructor", or:

cd ComfyUI/custom_nodes
git clone https://github.com/Lex-DRL/ComfyUI-StringConstructor

Restart. The only dependency is frozendict, and there are no models to download. Needs ComfyUI 0.18+.

Two things to remember if you land here via an old workflow: the deprecated node and the current one are interchangeable, so feel free to swap in the new Validate Dict to stop seeing the OLD badge; and since v3.x the nodes that build dictionaries were split into the separate ComfyUI-DictTools pack. Neither change breaks what this node does - it's a pass-through validator, and that job hasn't changed.