java.lang.String cannot be cast to clojure.lang.IFn

Question

I am trying to add some data into app engine datastore. This is my function

(defn createUser [email phone roleId status]
  (println (db/isIdExist "users" "email" email))
  (if (db/isIdExist "users" "email" email) 
    (str "false")
    ((db/addUser email phone roleId status) (str "true"))))

Here I want to print false in body according to the value of isIdExist function (which returns true if email already exists else false) now when I run this, If isIdExist == true then it prints false but when isIdExist == false it adds the value in datastore but gives this error. Can someone please help why it is happening and what concept of clojure am I missing here? Thanks

Lee · Accepted Answer · 2016-11-22 23:37:59Z

5

I assume db/addUser returns a string in which case you're trying to invoke the return value as a function. It looks like you want to perform the insert then return "true" so you can use do to sequence the two:

(if (db/isIdExist "users" "email" email) 
  "false"
  (do
    (db/addUser email phone roleId status) 
    "true"))))

answered Nov 22, 2016 at 23:37

Lee

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Comments

Chris Murphy · Accepted Answer · 2016-11-23 01:32:23Z

4

In Clojure ))))))) is totally normal and you see it everywhere, no cause for concern.

On the other hand (( should stand out and catch your eye. It very often means:

someone is returning a function.
that function should be immediately run.

This pattern is not wrong in any way, just learning to spot it is a useful way to get used to reading Clojure code quickly. In this case it likely means there are too many opening (s in

((db/addUser email phone roleId status) (str "true"))))

edited Nov 23, 2016 at 1:32

Chris Murphy

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answered Nov 22, 2016 at 23:54

Arthur Ulfeldt

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