clear a tjsonobject

[JIMSMITH 1]

Is there a way to remove pairs, as in all pairs, from a tjsonobject?  Looking for something like tjsonobject.clear.

[pyscripter 740]

There is:

function TJSONObject.RemovePair(const PairName: string): TJSONPair;
 

To clear all pairs:

JsonObject.SetPairs([]);

 

You could also Free the JsonObject and create a new one.

[JIMSMITH 1]

If I try the setpairs above I receive the message below when compiling.

 

[dcc32 Error] UfrmChannelConfig.pas(161): E2010 Incompatible types: 'System.Generics.Collections.TList<System.JSON.TJSONPair>' and 'Set'

[Dave Nottage 600]

54 minutes ago, JIMSMITH said:

Is there a way to remove pairs, as in all pairs, from a tjsonobject?

Not "out of the box". You could perhaps do this:

while LJSONObject.Count > 0 do
  LJSONObject.RemovePair(LJSONObject.Pairs[0].JsonString.Value).Free;

 

[Remy Lebeau 1545]

1 hour ago, pyscripter said:

To clear all pairs:

JsonObject.SetPairs([]);

That won't work. SetPairs() expects a list, not a Set or an array.

 

You would need to use this instead:

JsonObject.SetPairs(TList<TJSONPair>.Create);

This is because SetPairs() takes ownership of the new list, freeing the old list. The list can't be nil or else you risk crashes on future operations on the TJsonObject.

Edited September 19, 2024 by Remy Lebeau