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Thread: Change a TJSONObject value?

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Permlink Replies: 1 - Last Post: Jun 1, 2017 8:37 PM Last Post By: Francesco Marano
Brian Wheatley

Posts: 60
Registered: 2/5/01
Change a TJSONObject value?  
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  Posted: Jun 1, 2017 6:55 PM

I have an application that is passing JSON objects to the server. I am able to convert them to TJSONObject without any trouble. I need to change one or more values then return the object to the client (web browser). No matter what I try to do or how I try to go about changing values Delphi is complaining that they are read only.

{"Oid":"{8D03643A-CAEA-4A21-8563-3E0890E30634}","UserName":"User 1","CertificationNumber":"OSHA-CERT007","LastCompany":"{D014A27E-0003-4A5D-8BD7-E37A772DEEDC}","LastLogon":"2017-06-03 21:49:48"}

I need to change the LastCompany and LastLogon properties.

How do I change values on a TJSONObject?

Thank you,
Brian Wheatley
Francesco Marano

Posts: 59
Registered: 11/18/02
Re: Change a TJSONObject value?
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  Posted: Jun 1, 2017 8:23 PM   in response to: Brian Wheatley in response to: Brian Wheatley

It is possible to remove the old value and add a new one, something like this:

  cJSONText = '{"Oid":"{8D03643A-CAEA-4A21-8563-3E0890E30634}","UserName":"User 1","CertificationNumber":"OSHA-CERT007","LastCompany":"{D014A27E-0003-4A5D-8BD7-E37A772DEEDC}","LastLogon":"2017-06-03 21:49:48"}';
procedure Test();
  LJSONValue : TJSONValue;
  LJSONPair : TJSONPair;
  LJSONValue := TJSONObject.ParseJSONValue( cJSONText );
  if (LJSONValue <> nil) and (LJSONValue is TJSONObject) then
    LJSONPair := TJSONObject(LJSONValue).RemovePair( 'LastCompany' );
    TJSONObject(LJSONValue).AddPair( 'LastCompany', TJSONString.Create( '123' ) );
    ShowMessage( LJSONValue.ToJSON );

Please note it has a drawback as it changes the fields order.
A better way is to create a shadow model, change the model and recreate the json text.

Regards, Francesco
Helpful Answer (5 pts)
Correct Answer (10 pts)

Server Response from: ETNAJIVE02