Metadata

[tonyhallett]

https://auth0.com/docs/manage-users/user-accounts/metadata

Does not specify how.

...or that overrides what an identity provider supplies.

I have used app_metadata to update nickname. https://auth0.com/docs/manage-users/user-accounts/metadata/metadata-fields-data#name-collision

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Use the Dashboard does not mention user_metadata , app_metadata. ( This page does )

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The lock library only does root fields and user_metadata at sign up.
https://github.com/auth0/lock/blob/b19e8c8375b5f3db6ee21373a5e583d40cbbe5b4/src/engine/classic/sign_up_pane.jsx#L50
https://github.com/auth0/lock/blob/b19e8c8375b5f3db6ee21373a5e583d40cbbe5b4/src/connection/database/actions.js#L106

You can create and update metadata using Rules, the Authentication API, the Management API, the Auth0 Dashboard, and the Lock library.

Use the Lock library to define, add, read, and update user_metadata.
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I would also suggest that it is mentioned on this page that additional sign up fields requires switching to Classic Universal Login and changing the template if Lock is not being embedded.