CODEWITHSUNDEEP
clojure
user443426
user443426

Reputation:

Remove item from list of records

I'm have a following structure:

(defrecord Member [id name salary role])  
(defrecord Project [id name duration])
(defrecord ProjectMember [project member])

(def project-member-records (ref ()))

(defn find-project-member-record [parm-proj-id parm-member-id]
  (filter #(let [project (.project %) 
             member (.member %) 
             proj-id (:id project)
             member-id (:id member)] 
             (and (= proj-id parm-proj-id)
                  (= member-id parm-member-id))) @project-member-records))

;;Sample func, does not work
(defn remove-project-member-record [proj-id member-id]
  (dosync (ref-set project-member-records (remove #(= (:id (.project %)) proj-id) @project-member-records))))

Now, i want to remove item from project-member-records. For instance, i want to remove item by project id and member id, like i'm finding record in find-project-member-record function. Or (and) i want remove item than i have record found by project-member-records, something like (remove (find-project-member-record 1 1) project-records) ;pseudo codeBut i dont know how i can do this.

Upvotes: 0

Views: 146

Answers (1)

jbm
jbm

Reputation: 2600

Using remove is correct, but find-project-member-record returns a sequence. Try

(defn remove-project-member-record [proj-id member-id]
  (let [it (first (find-project-member-record proj-id member-id))]
    (dosync
     (ref-set project-member-records
              (remove #(= % it) @project-member-records)))))

If find-project-member-record always returns either an empty sequence or a sequence with one item, it may make sense for it to instead return either the item itself or nil. (e.g., call first on the result of filter in find-project-member-record rather than in remove-project-member-record and elsewhere).

Here's how you can structure it if you want everything to be wrapped in the dosync transaction:

(defn remove-project-member-record [proj-id member-id]
  (dosync
   (let [it (first (find-project-member-record proj-id member-id))]
     (ref-set project-member-records
              (remove #(= % it) @project-member-records)))))

Upvotes: 1

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