Question 109290 in Json Question posted in
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In Delphi, how to deserialize a JSON document from std::map in C++?

I have some json string come from c++, std::multimap<double,std::string>,this json string such as:

"{"name":"mark","data":[1,2,3,4],"some":"11.1":"Hello","22.2":",","44.4":"World"}}".

When I try to use mormot to deserialize this JSON string, it is failure, I don’t have a appropriate struct to receive it!

So, in Delphi, How can I deserialize this json string :"{"1.1":"Hello","2.2":"world"}" to TDictionary<double,string>?

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2

Answers


  1. Chosen as BEST ANSWER
    0

    this is my test code,it can work now.thanks!

    TDstring = TDictionary<double, string>;

    class procedure c_method.CustomReadClass(var Context: TJsonParserContext; Instance: TObject);
var doc: TDocVariantData;
begin
  if Context.ParseObject then
  begin
    if not assigned(Instance) then Instance := TDstring.Create;

    TDstring(Instance).Clear;

    var s : u8string := add_bracket(Context.json); //'{ ' + Context.json + ' }'

    doc.InitJson(s);
    var nameList := doc.Names;

    for var i :integer := 0 to High(nameList) do
    begin
      TDstring(Instance).TryAdd(To_string(nameList[i]).ToDouble, doc.s[nameList[i]]);
    end;

    Context.ParseEndOfObject;
    Context.Valid := true;
  end;

end;

initialization
TRttiJson.RegisterCustomSerializerClass(TDstring, c_method.CustomReadClass, nil);

finalization
TRttiJson.UnRegisterCustomSerializerClass(TDstring);

  2. 0

    I am sure there are many ways of doing this. We use the SuperObject library.

    Include SuperObject in your uses clause and then you can parse your object and access the values like this…

    var
  obj: ISuperObject;
  val: string;
begin
  obj := SO('{"foo": true}');
  { .S is just one of many helper functions. }
  val := obj.AsObject.S['foo']
end;

    If you don’t know the key:value pairs in advance you can iterate over the object like this.

    var
  item: TSuperAvlEntry;
begin
  for item in obj.AsObject do
  begin
    item.Name;
    item.Value;
  end;
end;
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