Clojurians Log v2

couple of questions can you do sub queries ? using d/q inside an existing d/q errors for me and i can not find any examples 😕

0. [ 54 #{ 1371 291 779 1101 734 ... } ]

:find ?pid (distinct (str ?n1 "-" ?n2)) 

@metasoarous this is what I’ve come up with so far, it almost looks like it would be worth looking into react for swing instead 😄 https://gist.github.com/stathissideris/7eb2d14990d0b23f8edbee53dbb7bc21

no attempts to avoid re-running queries, it’s not my main problem anyway — updating the UI is

@oliver.marks I'm not exactly following your use-case, but whenever you want to run sub-queries, just remember you can run multiple queries (possibly interleaved with data-munging using regular clojure functions); Sub queries like in SQL engines are necessary, because you want queries to be atomic (here you have a derefed immutable value); or to save on networking bandwidth (here your entire working set is already in memory).

should i run these queries separately ? ie (d/q [query]) (d/q [query]) then combine the results some how in my head I would do (dq [query (d/q query entity-id]) ie have a sub query that looks up based on values in the first query

I am finding what i want to do quite complex, i can get half way there but combining is the tricky part, I am pulling a product then combining all combinations of 2 attributes against that record but I want to use a different value when it exists

so think one product many prices, but not all prices exist in which case i want the record to be zero, I can select the price eid but this gives me many prices to one product and i need it to be a row ie product [price1 price2 price3] every product needs 3 prices but some may only have a single price entered in which case i should still get the 3 prices and the missing values should be 0

this way i can map over the result set and generate a csv

what's the relationship? :price/product or :product/price?

currently i am using distinct which is giving me a product entity and a set of price entities, my plan is to pull on each price entity and perhaps do a map merge to fill in the missing values

:price/product

so products do not have a price entity in them

(d/q '[:find ?product-entity (distinct ?e)
         :where [?e :price/product ?product-entity]] @conn)

so I can use that to get a product entity with a set of price entites against each product

what about something like?

(d/q '[:find (pull ?e [:product/id {:price/_product [:price/value]}])
       :where [?e :product/id]]
     db)

bear with me while i do some testing 🙂

The pull does a reverse-join (but will still return products even if no prices exist); Then you would need to do some data-wrangling on the resultset to get it in a form that you need for your CSV (adding default zeros, etc.)

yeah I might be able to work with this, got a couple of question can you use functions in a pull like you can in a query where

say i want to rename :price/value to be the composite of two other attributes ?

[(?make-keyword ?n ?c ?amount) ?kw]

no, that's what I meant about the data munging; You want to use where clauses to filter out the data you're interested; pull to fetch all the data you need to work with; and then clojure to do the data-munging 🙂

(let [results (d/q ...)
      final-results (some-data-munging ...)] ...) 

perhaps that's where i am going wrong trying to do to much in datalog

IMO, that kind of stuff only belongs in the where clause if you want to use ?kw for further filtering

okay good to know I was using it then doing (distinct ?kw) to get a set of values against a product with the set being the keyword i actually needed

A classic example is sorting:

(let [sorting-data (d/q '[:find ?only ?keys ?used ?for ?sorting ...])
      sorted (sort-by some-fn sorting-data)
      actual-data (d/pull-many [:data :to :view] (map :db/id sorted))])

^ notice that the keys you sorted by may not even show up in the pulled data you're interested in

yeah thanks for bearing with me, trying to expand the example to pull in the extra data I need

(refined after working on it a bit)