Can't figure out how to empty database with listeners about datascript HOT 4 CLOSED

I’m planning to add this functionality as I’m often find myself in need for reset! to swap DB value without transaction, but with listeners. Best you can do right now is probably something like this:

(defn db-reset! [conn db]
  (let [report (datascript.core/map->TxReport { :db-before @conn, :db-after db})]
    (reset! conn db)
    (doseq [[_ callback] @(:listeners (meta conn))]
      (callback report))))

It depends on some internals, but should fit for now until I add something like this to the API.

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It’ll be wonderful when this gets added. When it does get implemented, it might be best to implement it as a transaction function that can be used in transact!, like :db/add and :db.fn/cas, instead of (or in addition to) a function like the above code, which acts directly on connections.

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@cigitia yep, sounds reasonable

On Sat, Feb 28, 2015 at 10:03 PM cigitia [email protected] wrote:

It’ll be wonderful when this gets added. When it does get implemented, it
might be best to implement it as a transaction function that can be used in
transact!, like :db/add and :db.fn/cas, rather than a function separate
from transact! that acts directly on connections.

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#45 (comment).

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Just added reset-conn! function to reset database value inside a conn and trigger all listeners. Usage example: https://github.com/tonsky/datascript/blob/master/test/datascript/test/conn.cljc

@cigitia I would pass on your idea for now, if you need that kind of function inside a transaction it’s not that hard to build for youself. Transactions totally support user-provided functions

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