Delphi XE5 JSON nested object - json

Question

I am trying to generate JSON, data source is a DB FireBird.
I have a schema to generate path like this:
schema:= TDictionary<string, string>.Create;
schema.Add('DBTableName1', 'nest1.valueKeyName1');
schema.Add('DBTableName2', 'nest1.valueKeyName2');
schema.Add('DBTableName3', 'nest2.valueKeyName1');
schema.Add('DBTableName4', 'nest3.valueKeyName1');
schema.Add('DBTableName5', 'nest3.valueKeyName2');
schema.Add('DBTableName6', 'nest4.valueKeyName1');
How to create function for generate path to make nested objects?
{
"nest1": {
valueKeyName1: DBTableValue1,
valueKeyName2: DBTableValue2,
},
"nest2": {
valueKeyName1: DBTableValue3
},
"nest5":{
"nest6": {
"key1": "value1",
"key2": "value2",
},
"nest7": {}
}
In JavaScript I can do something like:
if (object.hasOwnProperty['key'] == false) object['key'] = {};
object = object['key'];
But in Delphi I have problem, and do not know, how to go deeper:
function TKlient.wprowadzWartoscDoJSON(wartosc: string; JSON: TJSONObject; sciezka: TStringList): TJSONObject;
var
i: integer;
obiekt: TJSONObject;
para: TJSONPair;
zagniezdzen: integer;
begin
zagniezdzen := sciezka.Count - 2;
obiekt := JSON;
para:= obiekt.Get(sciezka[i]);
for i := 1 to zagniezdzen do
begin
if obiekt.Get(sciezka[i]) = nil then obiekt.AddPair(sciezka[i], TJSONObject.Create)
else obiekt := obiekt.Get(sciezka[i]);
end;
obiekt.AddPair(sciezka[sciezka.Count - 1], wartosc);
result := obiekt;
end;

Answer 1

Here I've used a TDictionary<string, TJSONObject> to keep track of the object paths.
var
schema: TDictionary<string, string>;
pathSchema: TDictionary<string{path to every object}, TJSONObject>;
pair: TPair<string, string>;
values: TStringDynArray;
jsonObj,
jsonChildObj,
jsonParentObj: TJSONObject;
path: string;
i: Integer;
begin
schema := TDictionary<string, string>.Create;
try
schema.Add('DBTableName1', 'nest1.valueKeyName1');
schema.Add('DBTableName2', 'nest1.valueKeyName2');
schema.Add('DBTableName3', 'nest2.valueKeyName1');
schema.Add('DBTableName4', 'nest3.valueKeyName1');
schema.Add('DBTableName5', 'nest3.valueKeyName2');
schema.Add('DBTableName6', 'nest4.valueKeyName1');
schema.Add('value1', 'nest5.nest6.key1');
schema.Add('value2', 'nest5.nest6.key2');
pathSchema := TDictionary<string, TJSONObject>.Create;
try
jsonObj := TJSONObject.Create;
try
for pair in schema do begin
values := SplitString(pair.Value, '.');
path := '';
jsonParentObj := jsonObj;
for i := Low(values) to High(values)-1 do begin
if i > 0 then
path := path + '.';
path := path + values[i];
if pathSchema.ContainsKey(path) then
jsonChildObj := pathSchema[path]
else begin
jsonChildObj := TJSONObject.Create;
jsonParentObj.AddPair(TJSONPair.Create(values[i], jsonChildObj));
pathSchema.Add(path, jsonChildObj);
end;
jsonParentObj := jsonChildObj;
end;
jsonChildObj.AddPair(TJSONPair.Create(values[High(values)], pair.Key));
end;
WriteLn(jsonObj.ToString);
finally
jsonObj.Free;
end;
finally
pathSchema.Free;
end;
finally
schema.Free;
end;
ReadLn;
end.
The above prints the following:
{
"nest4":{
"valueKeyName1":"DBTableName6"
},
"nest2":{
"valueKeyName1":"DBTableName3"
},
"nest5":{
"nest6":{
"key1":"value1",
"key2":"value2"
}
},
"nest1":{
"valueKeyName1":"DBTableName1",
"valueKeyName2":"DBTableName2"
},
"nest3":{
"valueKeyName1":"DBTableName4",
"valueKeyName2":"DBTableName5"
}
}