Hi all,

For my current project, I download a file from a server that contains JSON code. I'm not sure how to read it into something that GetJSON is able to handle.

My first thought was using TStrings, however not sure how to convert a TString into TStream.

Any assistance would be much appreciated.

Chris

I download a file from a server that contains JSON code. I'm not sure how

to read it into something that GetJSON is able to handle.

Can't you figure out from the function interface:
http://www.freepascal.org/docs-html/fcl/fpjson/getjson.html

I do it like this, with TStringStream:

  lStrings := TStringList.Create;
  try
    lStrings.LoadFromFile(AFile);
    // Parse JSON data
    lStream := TStringStream.Create(lStrings.Text);
    lParser := TJSONParser.Create(lStream);
    try
      lParser.Strict := False;
      lData := lParser.Parse;
    finally
      lParser.Free;
      lStream.Free;
    end;

Well, in my particular case I use TStringList because I pre-process the data, removing comments which are not allowed in JSON.

The following will read JSON and write all keys it finds

uses jsonparser, fpjson, sysutils, classes;
Var
   F : TFileStream;
   D : TJSONData;
   E : TJSONEnum;
begin
   D:=Nil;
   F:=TFileStream.Create('myfile.json',fmOpenRead or fmShareDenywrite);
   try
     D:=GetJSON(F);
     for E in D do
       Writeln(E.Key, ' : ',E.Value.AsJSON);
   Finally
     D.free;
     F.Free;
   end;
end.

Michael.

As it happens, I have yesterday committed an extension which allows you to specify that the JSON supports comments. Both // and /* */ are detected and discarded.

Michael.

s/supports/contains/ , obviously.

Michael.

Dentist.pas(56,18) Error: Incompatible type for arg no. 1: Got
"TStringList", expected "TStream"

This is what I get when I use:

function ReadJSON (jsonfile, node:string) : string;
var
    json: tStringlist;
    J: TJSONData;
begin
   json:=TStringList.Create;
   json.loadfromfile(jsonfile);
   J:=GetJSON(json);    // Error is here.
   ReadJSON := J.FindPath(node).AsString;
end;

Does this mean my Lazarus / FPC is out of date? Or I'm using the wrong library or something?

Chris

GetJSON doesn't allow a Tstrings argument. Where did you get that from ?

Please check the sample code I sent.

Michael.

I do apologize, I was looking at a web page and found I didn't read it well enough. Thanks for your code suggestion, I will see about making it work for me.

Chris

Michael Van Canneyt wrote

As it happens, I have yesterday committed an extension which allows you to specify that the JSON supports comments. Both // and /* */ are detected and discarded.

Great! =)

J:=GetJSON(json); // Error is here.

quick fix:

J:=GetJSON(json.text);