Improve select-build-servers to convert strings to appropriate types

guix-data-service/model/build-server.scm

@@ -1,9 +1,19 @@
 (define-module (guix-data-service model build-server)
+  #:use-module (ice-9 match)
   #:use-module (squee)
   #:export (select-build-servers))
 
 (define (select-build-servers conn)
-  (exec-query conn
-              (string-append
-               "SELECT id, url, lookup_all_derivations "
-               "FROM build_servers")))
+  (define query
+    "
+SELECT id, url, lookup_all_derivations
+FROM build_servers
+ORDER BY id")
+
+  (map
+   (match-lambda
+     ((id url lookup-all-derivations)
+      (list (string->number id)
+            url
+            (string=? lookup-all-derivations "t"))))
+   (exec-query conn query)))