add caqti device

src/database.ml

@@ -0,0 +1,25 @@
+(* TODO
+   GNU Taler db-events
+   https://git.gnunet.org/gana.git/tree/gnu-taler-db-events/registry.rec *)
+
+let test req server _ =
+  let pool = Vif.Server.device Devices.caqti server in
+  let query =
+    let open Caqti_request.Infix in
+    Caqti_type.(unit ->! int) "SELECT 53 - 11"
+  in
+  let fn (module Conn : Caqti_miou.CONNECTION) = Conn.find query () in
+  match Caqti_miou_unix.Pool.use fn pool with
+  | Ok n ->
+      let open Vif.Response.Syntax in
+      let* () =
+        Vif.Response.add ~field:"content-type" "text/plain; charset= utf-8"
+      in
+      let* () = Vif.Response.with_string req (Fmt.str "53 - 11 = %d@." n) in
+      Vif.Response.respond `OK
+  | Error err ->
+      (* TODO don't leak private data in error messages *)
+      let open Vif.Response.Syntax in
+      let str = Fmt.str "Database error: %a." Caqti_error.pp err in
+      let* () = Vif.Response.with_string req str in
+      Vif.Response.respond `Internal_server_error