Class cast exception in clojure - exception

Question

Getting clojure.core$count cannot be cast to java.lang.Number error for defined variable count
(defroutes jobs-routes
(context "/jobs" []
(POST "/jobValidation" [name status req] (insert-job jobName jobStatus req)))
In this method I've define a variable count to store the value of total count from the query
(defn insert-job [jobName jobStatus req]
(let [count (db/insert-job {:job-name name :status status})])
(when (> count 0) (println (format "true" )))
(insert-job req) ;
)
Query: db/insert-job
-- :name insert-jobWithValidation :? :*
SELECT count(*) FROM job_history WHERE job_name = :job-name and status = :status
Problem
I want to check that whether If I'm getting out value greater than 0 so I can print something any if count is any positive value then I can perform something new

Answer 1

Your let block has no body, you're closing it right after definitions vector:
(let [count (db/insert-job {:job-name name :status status})])
Note that you are shadowing core function count here.
So when you call this line:
(when (> count 0) (println (format "true" ))), the value of count is count function:
count
=> #object[clojure.core$count 0x69c6a700 "clojure.core$count#69c6a700"]
(> count 0)
Execution error (ClassCastException)
class clojure.core$count cannot be cast to class java.lang.Number
There are some other errors and style inaccuracies:
the names of your variables don't match (jobName jobStatus vs name status)
you're calling (insert-job req) with only one argument, but this function has three
(> ... 0) is pos?
(format "true") is just "true"
Possible fix (maybe you will still have to modify it somehow):
(defn insert-job [job-name job-status req]
(let [my-count (db/insert-job {:job-name job-name :status job-status})]
(if (pos? my-count)
(println "true")
(insert-job job-name job-status req))))

Answer 2

that is probably because of your hugsql query header:
:? :* - returns the rowset, which is not a number.
maybe :? :1 would be more suitable here. Anyway, the query doesn't return a count(*), it rather returns a hash-map (in case of :1) or a list of one hashmap (in case of :*), you would still need to retrieve the value from there.
Something like that (untested):
-- :name insert-jobWithValidation :? :1
SELECT count(*) as amount FROM job_history WHERE job_name = :job-name and status = :status
(defn insert-job [name status req]
(let [res (db/insert-job {:job-name name :status status})]
(when (-> res :amount pos?)
(println true))
(insert-job req)))
UPD: omg, let with no body, indeed, #Martin Půda, thanks )
i would say, what you want is something like that:
-- :name count-jobs-by-name-and-status :? :1
SELECT count(*) as amount FROM job_history WHERE job_name = :job-name and status = :status
(defn insert-job-if-not-exists [name status req]
(if (->> {:job-name name :status status}
db/count-jobs-by-name-and-status
:amount
pos?)
(println "job already exists")
(insert-job req)))