https://github.com/cgrand/xforms/blob/master/src/net/cgrand/xforms.cljc#L371

your approach is correct, but notice that you can generalize it by passing a rf instead of a xform then you don't have to accumulate into (conj) which is an empty vector

Prismatic plumbing has a function like this. But I find groupby followed by update-vals is usually OK. I don't use the more complicated groupby in prismatic. Also specter offers easy transformations, but at the cost of learning specter

Thanks! Good advice. I also realized now that my implementation group-by2 may not work correctly if the transducer is stateful because the same state will be shared between different keys. And flushing would be needed, too.

seconding xforms, by-key is very useful

https://cnuernber.github.io/ham-fisted/ham-fisted.api.html#var-group-by-reduce

http://aphyr.github.io/tesser/tesser.core.html#var-facet

http://aphyr.github.io/tesser/tesser.core.html#var-group-by

Build a command that pipes the data into gzip and then into a file. You'll probably need to use sh -c for that.

How do I pipe data using sh ? 🙂

Something like (shell/sh "sh" "-c" "mysqldump ... | gzip -c c > /tmp/data.gzip").

Right now I'm doing (apply shell/sh "mysqldump" vec-of-arguments-to-mysqldump)

Oh, so using -c I can paste the full mysqldump command?

As a string

Yep.

It ran, but the resulting file was 0 bytes

The dump works, if I use > dump.sql at the end instead of piping to gzip, I get the dump file.

Oh, I removed the extra c in your example and then it worked perfectly

Thanks!

Seems to work even without an additional -c (shell/sh "sh" "-c" "mysqldump ... | gzip > /tmp/data.gzip")

mysqldump warns that providing the password on the command line is insecure. Is this a real issue when sending commands to the shell like this? If it's an issue, can I somehow "send in" an option file (from a string) with the password (as described here https://dev.mysql.com/doc/refman/8.0/en/password-security-user.html) or must I create the option file with the password, pass it as argument, and then delete it?

Oh, sorry - it was supposed to be gzip -c -. But gzip seems to be clever enough so that it doesn't need all that.

> Is this a real issue when sending commands to the shell like this? It is - any other software running under the same user will be able to see the password while that sh -c ... is running. Also, if that command is logged by your system or app, anything that can access those logs will also be able to see the password in plain text. An option file is probably more safe, but isn't perfect unless the user that's used to run your app has its files inaccessible to anything else. The best solution is probably to send the password to the mysqldump process directly, if it supports that - e.g. via its stdin.

Just took a look at that link - yeah, it pretty much says the same thing.

There doesn’t seem to be a way to pass the password through stdin?

Probably, I don't know the MySQL client well enough. BTW another potential approach here could be embedding the client library itself via JNI. But that's much more of a hassle, you probably don't need it.

https://github.com/nubank/matcher-combinators and https://github.com/HealthSamurai/matcho are the two leading libraries in this space afaik

I use matcher-combinators from time to time. Athough using nested destructuring can get you surprisingly far, e.g.:

(let [[{:keys [public-id]
        :as parsed-response}
       :as all]
      (-> response :body (json/read-str :key-fn keyword))]
  (testing (pr-str all)
    (is (logic.common/valid-uuid-str? public-id))))

Thank you very much!!

Worked! Thanks again!

What I've seen once was that likely: (is (match? {:alpha keyword?} {:alpha :beta}))