Parsing JSON in Delphi with slashes - json

Question

I receive JSON strings from a WebService with slashes in it.
When I parse them, Delphi adds backslashes.
V := TJSONObject.ParseJSONValue( '{"Kode":"ABC/123" }') ;
V.ToString returns : {"Kode":"ABC\\/123"}
What is best practice to parse JSON strings in Delphi?
And why does the function V.Value always returns an empty string?
In the unit System.JSON, I see the following code:
function TJSONAncestor.Value: string;
begin
Result := '';
end;
Do I need to add code myself to System units that ship with Delphi?

Answer 1

\ is required to be escaped as \\, so your claim that "Just removing the backslash in the result does not work, because the value could also be "ABC\123"" is wrong, as it would have to be "ABC\\123" instead.
The only other character required to be escaped is " as \". / is certainly not required to be escaped, but it MAY be escaped at the discretion of the implementation. It is not invalid to do so. As to WHY ToString() does that, you would have to ask Embarcadero.
If you needed to, you could easily do a search-and-replace of \/ into / without affecting other escape sequences, like \\ and \". Or, try using ToJSON() instead of ToString().
Regarding TJSONAncestor.Value(), TJSONAncestor is a base class, and its Value() is a virtual method that returns a blank string by default. Descendant classes (JSONString, TJSONNumber, etc) can override Value() to return more meaningful strings. But in your example, your input string represents a JSON object, so V will be pointing at a TJSONObject instance, and TJSONObject does not override Value() because it does not make sense for an object to be represented by a string. This is even documented behavior:
http://docwiki.embarcadero.com/Libraries/en/System.JSON.TJSONAncestor.Value
Returns the string representation of a simple JSON element like a string, number or boolean.
For structured JSON elements like an object and array returns empty string.