Vim: Show all lines not matching a pattern

I have a json documen开发者_开发百科t with the following data.

"tag": null

I would like to find all the tags that don't have null.

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You can use the :v command:

:v/"tag": null/

Alternatively, you can use a search with a negative look-ahead assertion (you can use set hlsearch to highlight the matches):

/"tag": \(null\)\@!