RPC: new client command and RPC to retrieve big map value by key

src/proto_alpha/lib_client/client_proto_context.ml

@@ -35,6 +35,9 @@ let get_balance (rpc : #Proto_alpha.rpc_context) ~chain ~block contract =
 let get_storage (rpc : #Proto_alpha.rpc_context) ~chain ~block contract =
   Alpha_services.Contract.storage_opt rpc (chain, block) contract
 
+let get_big_map_value (rpc : #Proto_alpha.rpc_context) ~chain ~block contract key =
+  Alpha_services.Contract.big_map_get_opt rpc (chain, block) contract key
+
 let get_script (rpc : #Proto_alpha.rpc_context) ~chain ~block contract =
   Alpha_services.Contract.script_opt rpc (chain, block) contract
 

src/proto_alpha/lib_client/client_proto_context.mli

@@ -39,6 +39,14 @@ val get_storage:
   Contract.t ->
   Script.expr option tzresult Lwt.t
 
+val get_big_map_value:
+  #Proto_alpha.rpc_context ->
+  chain:Shell_services.chain ->
+  block:Shell_services.block ->
+  Contract.t ->
+  (Script.expr * Script.expr) ->
+  Script.expr option tzresult Lwt.t
+
 val get_script:
   #Proto_alpha.rpc_context ->
   chain:Shell_services.chain ->

src/proto_alpha/lib_client_commands/client_proto_context_commands.ml

@@ -62,6 +62,11 @@ let file_parameter =
       else
         return p)
 
+let data_parameter =
+  Clic.parameter (fun _ data ->
+      Lwt.return (Micheline_parser.no_parsing_error
+                  @@ Michelson_v1_parser.parse_expression data))
+
 let group =
   { Clic.name = "context" ;
     title = "Block contextual commands (see option -block)" }
@@ -133,6 +138,28 @@ let commands version () =
             return_unit
       end ;
 
+    command ~group ~desc: "Get the value associated to a key in the big map storage of a contract."
+      no_options
+      (prefixes [ "get" ; "big" ; "map" ; "value" ; "for" ]
+       @@ Clic.param ~name:"key" ~desc:"the key to look for"
+         data_parameter
+       @@ prefixes [ "of" ; "type" ]
+       @@ Clic.param ~name:"type" ~desc:"type of the key"
+         data_parameter
+       @@ prefix "in"
+       @@ ContractAlias.destination_param ~name:"src" ~desc:"source contract"
+       @@ stop)
+      begin fun () key key_type (_, contract) (cctxt : Proto_alpha.full) ->
+        get_big_map_value cctxt
+          ~chain:`Main ~block:cctxt#block
+          contract (key.expanded, key_type.expanded) >>=? function
+        | None ->
+            cctxt#error "No value associated to this key."
+        | Some value ->
+            cctxt#answer "%a" Michelson_v1_printer.print_expr_unwrapped value >>= fun () ->
+            return_unit
+      end ;
+
     command ~group ~desc: "Get the storage of a contract."
       no_options
       (prefixes [ "get" ; "script" ; "code" ; "for" ]

src/proto_alpha/lib_protocol/src/contract_services.ml

@@ -127,6 +127,16 @@ module S = struct
       ~output: Script.expr_encoding
       RPC_path.(custom_root /: Contract.rpc_arg / "storage")
 
+  let big_map_get =
+    RPC_service.post_service
+      ~description: "Access the value associated with a key in the big map storage  of the contract."
+      ~query: RPC_query.empty
+      ~input: (obj2
+                 (req "key" Script.expr_encoding)
+                 (req "type" Script.expr_encoding))
+      ~output: (option Script.expr_encoding)
+      RPC_path.(custom_root /: Contract.rpc_arg / "big_map_get")
+
   let info =
     RPC_service.get_service
       ~description: "Access the complete status of a contract."
@@ -187,6 +197,15 @@ let register () =
           unparse_script ctxt Readable script >>=? fun (script, ctxt) ->
           Script.force_decode ctxt script.storage >>=? fun (storage, _ctxt) ->
           return_some storage) ;
+  register1 S.big_map_get (fun ctxt contract () (key, key_type) ->
+      let open Script_ir_translator in
+      let ctxt = Gas.set_unlimited ctxt in
+      Lwt.return (parse_ty ctxt ~allow_big_map:false ~allow_operation:false (Micheline.root key_type))
+      >>=? fun (Ex_ty key_type, ctxt) ->
+      parse_data ctxt key_type (Micheline.root key) >>=? fun (key, ctxt) ->
+      hash_data ctxt key_type key >>=? fun (key_hash, ctxt) ->
+      Contract.Big_map.get_opt ctxt contract key_hash >>=? fun (_ctxt, value) ->
+      return value) ;
   register_field S.info (fun ctxt contract ->
       Contract.get_balance ctxt contract >>=? fun balance ->
       Contract.get_manager ctxt contract >>=? fun manager ->
@@ -249,3 +268,6 @@ let storage ctxt block contract =
 
 let storage_opt ctxt block contract =
   RPC_context.make_opt_call1 S.storage ctxt block contract () ()
+
+let big_map_get_opt ctxt block contract key =
+  RPC_context.make_call1 S.big_map_get ctxt block contract () key

src/proto_alpha/lib_protocol/src/contract_services.mli

@@ -78,5 +78,9 @@ val storage:
 val storage_opt:
   'a #RPC_context.simple -> 'a -> Contract.t -> Script.expr option shell_tzresult Lwt.t
 
+val big_map_get_opt:
+  'a #RPC_context.simple -> 'a -> Contract.t -> Script.expr * Script.expr ->
+  Script.expr option shell_tzresult Lwt.t
+
 
 val register: unit -> unit