Looking for containskey when processing data

[JIMSMITH 1]

I am using Delphi 10.1 update2.  When processing a json file I cannot find the containskey method with a TJSONObject?  Is there a work around to the the equivalent check JSONObject.containskey('keyvalue') for this version of Delphi?

 

[Remy Lebeau 1535]

15 hours ago, JIMSMITH said:

I am using Delphi 10.1 update2.  When processing a json file I cannot find the containskey method with a TJSONObject?

TJSONObject does not have a ContainsKey() method, in any version of Delphi.  If you want that, you can use a class helper, eg:

type
  TJSONObjectHelper = class helper for TJSONObject
    function ContainsKey(const AKeyName: String): Boolean;
  end;

function TJSONObjectHelper.ContainsKey(const AKeyName: String): Boolean;
begin
  Result := Self.GetValue(AKeyName) <> nil;
end;

...

if JSONObject.ContainsKey('keyvalue') then

15 hours ago, JIMSMITH said:

Is there a work around to the the equivalent check JSONObject.containskey('keyvalue') for this version of Delphi?

As you can see above, you can use the TJSONObject.GetValue() method, which returns nil if the specified key is not found, eg:

if (JSONObject.GetValue('keyvalue') <> nil) then

 

Edited February 18 by Remy Lebeau

[pyscripter 739]

 

7 minutes ago, Remy Lebeau said:

Use the TJSONObject.GetValue() method

 

There is also TryGetValue<T>.

[Remy Lebeau 1535]

5 hours ago, pyscripter said:

There is also TryGetValue<T>.

True, though it is inherited from TJSONValue and not specific to TJSONObject, it has a little more overhead as it performs path processing on the input string and type validation on the output value, and it requires the caller to declare a variable to receive the output value whether the caller actually wants it or not.

Edited February 18 by Remy Lebeau