I have a Delphi program written in Alexandria 11.1 that needs to send a JSON file to a service that is written in C#. If the JSON structure is static, I create a model class and use the native TJson.ObjectToJsonString
of REST.Json
to convert it to JSON string.
For example, a static JSON like:
{
"pair1": "value1",
"pair2": "value2",
"array": [
{
"PairString": "1",
"PairInt": 1
},
{
"PairString": "2",
"PairInt": 2
}
]
}
This is implemented with a Delphi class like:
TMyItem = class
public
PairString: string;
PairInt: Integer;
end;
TExample = class
public
pair1: string;
pair1: string;
array: TArray<TMyItem>;
end;
How can I create a similar model for a dynamic set of pairs? Is it possible in that way?
For example, a JSON like:
{
"dictionary": {
"key1": "KeyValue1",
"key2": "KeyValue2",
"key3": "KeyValue3",
.....
"keyN": "KeyValueN"
}
}
In C#, that is implemented with the use of a Dictionary
. In Delphi, TDictionary
or TObjectDictionary
when serialized, extracts all the members of the class and produces a different and invalid structure.
I have tried to use REST.JsonReflect
and create a custom JsonReflectAttribute
and TJSONInterceptor
and implement ObjectConverter
in order to edit the final TJSONObject
and add the pairs dynamically.
The following code intercepts and converts the dictionary to TJSONObject
, which also extracts an invalid structure, because it is serialized as a class.
uses System.Rtti, Rest.Json, System.Generics.Collections, Rest.JsonReflect;
type
TDictionaryInterceptor = class(TJSONInterceptor)
public
function ObjectConverter(Data: TObject; Field: string): TObject; override;
end;
function TDictionaryInterceptor.ObjectConverter(Data: TObject; Field: string): TObject;
function DictionaryToJsonObject(ADictionary: TDictionary<string, string>): TJSONObject;
var
JsonObject: TJSONObject;
KeyValuePair: TPair<string, string>;
begin
JsonObject := TJSONObject.Create;
try
for KeyValuePair in ADictionary do
begin
JsonObject.AddPair(TJSONPair.Create(TJSONString.Create(TValue.From<string>(KeyValuePair.Key).ToString),
TJSONString.Create(TValue.From<string>(KeyValuePair.Value).ToString))
);
end;
Result := JsonObject;
finally
end;
end;
var
ctx: TRttiContext;
Dict: TObjectDictionary<string, string>;
RttiProperty: TRttiProperty;
begin
RttiProperty := ctx.GetType(Data.ClassInfo).GetProperty(Copy(Field, 2, MAXINT));
Dict := TObjectDictionary<string, string>(RttiProperty.GetValue(Data).AsObject);
Result := DictionaryToJsonObject(Dict);
end;
DictionaryReflectAttribute = class(JsonReflectAttribute)
public
constructor Create;
end;
constructor DictionaryReflectAttribute.Create;
begin
inherited Create(ctObject, rtObject, TDictionaryInterceptor);
end;
TExample = class
public
[DictionaryReflectAttribute]
dictionary: TObjectDictionary<string, string>;
end;
Is this the correct direction, or is there an alternative way to serialize TDictionary
in the form of the example?