url json data question
lazarus / 38-Networking and Web Programming

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Aruna · 2022-12-20 01:39

I am experimenting with JSON out there on the public domain internet
and my code works ( sort of ).

I have a Tbutton which when clicked goes and grabs the JSON data from
the openweathermap.org weather API and displays this in the Tmemo.
This part works. As can be seen below. I was checking the current
weather in Mongolia.
Code: Bash  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i {"coord":{"
lon":106.8832,"lat":47.9077},"weather":[{"id":802,"main":"Clouds","des
cription":"scattered clouds","icon":"03d"}],"base":"stations","main":{
"temp":-25.93,"feels_like":-32.93,"temp_min":-25.93,"temp_max":-
25.93,"pressure":1016,"humidity":76},"visibility":10000,"wind":{"speed
":4,"deg":170},"clouds":{"all":40},"dt":1671499205,"sys":{"type":1,"id
":9644,"country":"MN","sunrise":1671496702,"sunset":1671526878},"timez
one":28800,"id":2028462,"name":"Ulaanbaatar","cod":200}
Now, How do I pick out a specific name: value(s) pair in that jason
response? My code is below.
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
Unit1; {$mode objfpc}{$H+} interface uses  Classes, SysUtils, Forms,
Controls, Graphics, Dialogs, StdCtrls, 
opensslsockets,fphttpclient,fpjson, jsonparser; type   { TForm1 }  
TForm1 = class(TForm)    Button1: TButton;    jsonData: TMemo;   
procedure Button1Click(Sender: TObject);  private   public   end; var 
Form1: TForm1;  jObj: TJSONObject;  jArr: TJSONArray; 
jEnum:TJSONEnum;  response: string; implementation {$R *.lfm}  {
TForm1 } procedure TForm1.Button1Click(Sender: TObject);   begin 
jArr:=TJSONArray.Create;   try     response:=TFPHTTPClient.SimpleGet('
https://api.openweathermap.org/data/2.5/weather?q=Ulaanbaatar&appid=a0
a47bddbbfe8e4c2905cf76f64b13ef&units=metric');     writeln(response); 
   jsonData.Lines.Text:=response;  finally     jArr.Free; 
end;  end;end. 
And this is from a youtube video I stumbled upon by accident Learn how
to consume JSON data in FreePascal which is from  Aug 23, 2020 is
there a better way to do things now or this is just fine?

Thanks, Aruna
PS: That is my active working API-Key so please use in moderation
thank you.

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paweld · 2022-12-20 06:12

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses 
fphttpclient, opensslsockets, fpjson, jsonparser; procedure
TForm1.Button1Click(Sender: TObject);var  json: String;  jd:
TJSONData;begin  json := TFPHTTPClient.SimpleGet('https://api.openweat
hermap.org/data/2.5/weather?q=Ulaanbaatar&appid=a0a47bddbbfe8e4c2905cf
76f64b13ef&units=metric');  jd := GetJSON(json);  Memo1.Lines.Text :=
jd.FormatJSON([], 2);  jd.Freeend; procedure
TForm1.Button2Click(Sender: TObject);var  jd, jdweather: TJSONData; 
i: Integer;begin  Memo2.Lines.Clear;  jd :=
GetJSON(Memo1.Lines.Text);  if jd.FindPath('.name') <> nil then   
Memo2.Lines.Add('City: ' + jd.GetPath('.name').AsString);  if
(jd.FindPath('.weather') <> nil) and (jd.GetPath('.weather').Count >
0) then  begin    jdweather := jd.GetPath('.weather');   
Memo2.Lines.Add('Description: ');    for i := 0 to jdweather.Count - 1
do    begin      if jdweather.Items[i].FindPath('.description') <> nil
then        Memo2.Lines.Add(Format('        %2d - %s', [i,
jdweather.Items[i].GetPath('.description').AsString]));    end;  end; 
if jd.FindPath('.main.temp') <> nil then    Memo2.Lines.Add('Temp: ' +
FormatFloat('0.00', jd.GetPath('.main.temp').AsFloat));  if
jd.FindPath('.main.humidity') <> nil then   
Memo2.Lines.Add(Format('Humidity: %3.1f%%',
[jd.GetPath('.main.humidity').AsFloat]));  jd.Freeend;

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PierceNg · 2022-12-20 06:12

Quote from: Aruna on December 20, 2022, 02:39:18 amNow, How do I pick
out a specific name: value(s) pair in that jason response?

And this is from a youtube video I stumbled upon by accident Learn how
to consume JSON data in FreePascal which is from  Aug 23, 2020 is
there a better way to do things now or this is just fine?

Below code produces following output:

Code: Text  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i % fpc
owpjson.lpr...29 lines compiled, 0.2 sec % ./owpjson      According to
Open Weather Maps: scattered clouds in Ulaanbaatar Heap dump by
heaptrc unit of /home/pierce/pascal/work/owp/owpjson228 memory blocks
allocated : 12049/12576228 memory blocks freed     : 12049/125760
unfreed memory blocks : 0True heap size : 360448True free heap :
360448
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
owpjson; {$mode objfpc}{$H+} uses  heaptrc, fpjson, jsonparser; const 
OWP_RESP = '{"coord":{"lon":106.8832,"lat":47.9077},"weather":[{"id":8
02,"main":"Clouds","description":"scattered clouds","icon":"03d"}],"ba
se":"stations","main":{"temp":-25.93,"feels_like":-32.93,"temp_min":-
25.93,"temp_max":-
25.93,"pressure":1016,"humidity":76},"visibility":10000,"wind":{"speed
":4,"deg":170},"clouds":{"all":40},"dt":1671499205,"sys":{"type":1,"id
":9644,"country":"MN","sunrise":1671496702,"sunset":1671526878},"timez
one":28800,"id":2028462,"name":"Ulaanbaatar","cod":200}'; var  jo1,
jo2: TJSONObject;  ja: TJSONArray; begin  jo1 := GetJSON(OWP_RESP) as
TJSONObject;  try    if jo1.Find('weather', ja) then      begin      
jo2 := ja.Extract(0) as TJSONObject;        writeln('According to
OpenWeatherMaps: ', jo2['description'].AsString, ' in ',
jo1['name'].AsString);        writeln;      end;  finally   
jo1.Free;    jo2.Free;    //ja.Free; // <=== This line causes access
violation.  end;end.
The heap dump part is to show no leak. Didn't watch the video you
linked.

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Aruna · 2022-12-21 02:01

Quote from: paweld on December 20, 2022, 07:12:24 amCode: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses 
fphttpclient, opensslsockets, fpjson, jsonparser; procedure
TForm1.Button1Click(Sender: TObject);var  json: String;  jd:
TJSONData;begin  json := TFPHTTPClient.SimpleGet('https://api.openweat
hermap.org/data/2.5/weather?q=Ulaanbaatar&appid=a0a47bddbbfe8e4c2905cf
76f64b13ef&units=metric');  jd := GetJSON(json);  Memo1.Lines.Text :=
jd.FormatJSON([], 2);  jd.Freeend; procedure
TForm1.Button2Click(Sender: TObject);var  jd, jdweather: TJSONData; 
i: Integer;begin  Memo2.Lines.Clear;  jd :=
GetJSON(Memo1.Lines.Text);  if jd.FindPath('.name') <> nil then   
Memo2.Lines.Add('City: ' + jd.GetPath('.name').AsString);  if
(jd.FindPath('.weather') <> nil) and (jd.GetPath('.weather').Count >
0) then  begin    jdweather := jd.GetPath('.weather');   
Memo2.Lines.Add('Description: ');    for i := 0 to jdweather.Count - 1
do    begin      if jdweather.Items[i].FindPath('.description') <> nil
then        Memo2.Lines.Add(Format('        %2d - %s', [i,
jdweather.Items[i].GetPath('.description').AsString]));    end;  end; 
if jd.FindPath('.main.temp') <> nil then    Memo2.Lines.Add('Temp: ' +
FormatFloat('0.00', jd.GetPath('.main.temp').AsFloat));  if
jd.FindPath('.main.humidity') <> nil then   
Memo2.Lines.Add(Format('Humidity: %3.1f%%',
[jd.GetPath('.main.humidity').AsFloat]));  jd.Freeend;
Thank you so much @paweld. As you can see from the attached screenshot
with your help things are working. Now I have to go through your code
and try to understand why it works.
Once again very much appreciate you taking the time. I suppose I
should not ask for a heavily commented version? :-D

Note to self: Why does no one comment anything anymore..

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Aruna · 2022-12-21 02:10

Quote from: PierceNg on December 20, 2022, 07:12:43 am
Below code produces following output:

Code: Text  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i % fpc
owpjson.lpr...29 lines compiled, 0.2 sec % ./owpjson      According to
Open Weather Maps: scattered clouds in Ulaanbaatar Heap dump by
heaptrc unit of /home/pierce/pascal/work/owp/owpjson228 memory blocks
allocated : 12049/12576228 memory blocks freed     : 12049/125760
unfreed memory blocks : 0True heap size : 360448True free heap :
360448
The heap dump part is to show no leak. Didn't watch the video you
linked.

This was a very pleasant surprise I had no idea it was this simple to
do this and check for leaks, amazing! I will test your code then get
back to you. Many thanks for taking your valuable time to help me.