Re: GNATCOLL JSON Parsing

["Björn Lundin" <b.f.lundin@gmail.com>]

On 2018-06-08 07:52, eduardsapotski@gmail.com wrote:
> I try understand parsing JSON in Ada. 
> 
> For example:
> Have web-api that gives simple JSON: http://api.exmo.com/v1/trades/?pair=BTC_USD&limit=10
> 
> I need to save this data to database.
> Created type:
> 
>    type Money is delta 0.00000001 range 0.0 .. 9_999_999_999.9;
>    type UTC_Date is range 1_500_000_000 .. 3_000_000_000;
> 
>    type Trade is record
> 
>       Trade_Id   : Integer;
>       Pair       : Unbounded_String;
>       Trade_Type : Unbounded_String;
>       Price      : Money;
>       Quantity   : Money;
>       Amount     : Money;
>       Date       : UTC_Date;
>       Saved      : Boolean;
> 
>    end record;
> 
> Created collection:
> 
>     package Vector_Trades is new Ada.Containers.Vectors(Natural, Trade);
> 
>     Trades : Vector_Trades.Vector;
> 
> Receive data:
> 
> JSON : Unbounded_String;
> 
> JSON := To_Unbounded_String(AWS.Response.Message_Body (AWS.Client.Get (URL => "http://api.exmo.com/v1/trades/?pair=BTC_USD&limit=10")));
> 
> What to do next? How to get list of objects from the JSON-text?


something like (not tested):
declare
   use gnatcoll.Json;
   current_item, Reply : JSON_Value := Create;
   BTC_Array : json_array := empty_array;
begin
  Reply := Read(Strm => Aws.Response.Message_Body(AWS_Reply),Filename =>
"");

  if reply.has_Field("BTC_USD") then
     btc_array := reply.Get("BTC_USD");
     if length(btc_array) > 0 then
        for i in 1 .. length(btc_array) loop
           Current_Item := Get(btc_array, i);
           declare
             tradeid : integer := 0;
           begin
             if Current_item.Has_Field("tradeid") then
               tradeid := current_item.Get(""tradeid);
             end if;
               ...
           end;
        end loop;
     end if;
  end if;
end;





> 
> How to save data to database already understood.
> 
> Thanks.
> 
> 
> 
> 
> 
> 


-- 
--
Björn