fpc/packages/fcl-json/examples/jsonpath.pp
Michaël Van Canneyt c47fc710ba * JSONPath demo
2024-03-09 11:09:44 +01:00

54 lines
1.1 KiB
ObjectPascal

program jsonpath;
{$mode objfpc}{$h+}
uses sysutils, classes,iostream,fpjson, jsonparser;
Procedure Usage(Msg : String);
begin
Writeln('Usage : jsonpath <path> [<file>]');
Writeln('Reads JSON from <file> or standard input if the <file> argument is not present');
Writeln('calculates <path> and prints path to stdout');
Writeln('if <path> does not exist in the JSON, null is printed');
Halt(Ord(Msg<>''));
end;
Var
S : TStream;
M : TMemoryStream;
D,P : TJSONData;
begin
if (ParamCount<1) then
Usage('Need path expression');
if (ParamStr(1)='-h') or (ParamStr(1)='--help') then
usage('');
if (ParamCount>1) then
S:=TFileStream.Create(ParamStr(2),fmOpenRead or fmShareDenyNone)
else
S:=TIOStream.Create(iosInput);
D:=Nil;
M:=Nil;
P:=Nil;
try
M:=TMemoryStream.Create;
M.CopyFrom(S,0);
M.Position:=0;
D:=GetJSON(M);
if D<>Nil then
P:=D.FindPath(ParamStr(1));
if Not Assigned(P) then
Writeln('null')
else
if P.JSONType in [jtArray,jtObject] then
Writeln(P.AsJSON)
else
Writeln(P.AsString);
Finally
M.Free;
S.Free;
D.Free;
end;
end.