Please provide an example of a working before_update callback

[JeremyCraigMartinez]

The before_update callback was introduced in v3.5. However, it is not clear to me how to get this to work. Every approach I've attempted has resulted in errors in the training process. How does one load a callback and pass it in as a callable? There are no working examples. All the documentation just has this set to = null. Since the config gets serialized, it appears to have a value of type str.

The following config:

[training]
dev_corpus = "corpora.dev"
train_corpus = "corpora.train"
...
before_to_disk = null
before_update = "module.before_update"

produces the error

Config validation error
training -> before_update   module.before_update is not callable

[JeremyCraigMartinez]

I also tried something with

import spacy

@spacy.registry.callbacks('cb_before_update')
def create_callback():
    def cb_before_update(nlp, _):
        pass

And referencing the callback by name, but I get the same error

[kinghuang]

For a registered callback function named cb_before_update, you can specify it like the following.

[training]
dev_corpus = "corpora.dev"
train_corpus = "corpora.train"
...
before_to_disk = null
before_update = {"@callbacks": "cb_before_update"}