parse json and extract all id value with ULKJson library7 - json

Question

I want to parse the JSON and extract all ID values and assign, show them in a combo box.
I am using ULKJson library and Delphi 7. Here is my JSON
{
"ID": null,
"ResCode": 100,
"ResMessage": "هیچ آیتم جدیدی در پایگاه داده ذخیره نشد",
"ResPos": null,
"ResData": {
"data": [
{
"data": {
"id": "2994LUZUWL",
"type": "SHEBAD_ID"
},
"sendDate": "2021-11-02T20:00:16.827"
},
{
"data": {
"id": "2992CQVAE1",
"type": "SHEBAD_ID"
},
"sendDate": "2021-11-02T18:43:12.857"
},
{
"data": {
"id": "Z2005KUU6ZB",
"type": "SHEBAD_ID"
},
"sendDate": "2021-11-02T18:51:36.107"
},
{
"data": {
"id": "Z29914MM2WL",
"type": "SHEBAD_ID"
},
"sendDate": "2021-11-02T19:21:08.607"
}
],
"message": "",
"succeeded": true
}
}
How can I access to ID values inside this JSON?

Answer 1

Delphi 6 user here, but same thing really..
You need to have uLKJson installed, which I assume you have.
You need to parse each element as one of the uLKJSON types:
jsBase, jsNumber, jsString, jsBoolean, jsNull, jsList, jsObject
You have
{ <<< root = object
"ResData": { <<< ResData = object
"data": [ <<< data = list
{ <<< element[0] = object
"data": { <<< data = object
"id": "2994LUZUWL", <<< id = string. This is what you want.
...
In jq, this would be selection string: ".ResData.data[].data.id".
The program to parse the data could look something like this:
program testparse;
{$APPTYPE CONSOLE}
uses
SysUtils, // for writing on console
ulkjson; // to parse JSON
var
vJsonObj: TlkJsonObject;
jo : TlkJSONstreamed;
listofelements: TlkJSONlist;
i : integer;
// {
// "data": {
// "id": "2994LUZUWL",
// "type": "SHEBAD_ID"
// },
// "sendDate": "2021-11-02T20:00:16.827"
// },
// function for simplicity
//
function get_key( j : TlkJSONobject) : string;
begin
try
result := j.Field['data'].Field['id'].Value;
except
result := 'N/A'; // if the id key is not there..
end;
end;
begin
jo := TlkJSONstreamed.Create;
try
vJsonObj := jo.LoadFromFile('jsontext.txt') as TlkJsonObject;
listofelements := vJsonObj.Field['ResData'].Field['data'] as TlkJSONlist;
for i := 0 to listofelements.Count-1 do
begin
writeln('Key no ' + inttostr(i) + '=' +
get_key(listofelements.Child[i] as TlkJSONobject)
);
end;
finally
jo.free;
end;
end.
Result:
Key no 0=2994LUZUWL
Key no 1=2992CQVAE1
Key no 2=Z2005KUU6ZB
Key no 3=Z29914MM2WL
Alternative library
Alternatively JSONTools, originally from Lazarus can be used. I have modified and uploaded a version for Delphi 6/7.
Using this unit:
writeln('-- doing it with JSONTools');
N := TJsonNode.Create;
n.LoadFromFile('jsontext.txt'); // will automatically do a parse
n:= n.Find('/ResData/data'); // get the array
for i := 0 to n.Count-1 do
begin
writeln(
'Key no ' + inttostr(i) + '=' +
n.Child(i).Find('data/id').AsString);
end;
n.Free;
Adding to a combobox
As the question was for how to add to a combobox: this is simple. First clear the combobox, then for each item do an "additem".