Delphi object to json string how to ignore empty and null fields

Question

I have a class for rest request as follows

TRedeemItemsClass = class
private
  [JSONName('RedeemCode')]
  FRedeemCode: String;
  [JSONName('AssetKey')]
  FAssetKey:String;
public
  property RedeemCode: String read FRedeemCode write FRedeemCode;
  property AssetKey:String read FAssetKey write FAssetKey;
  function ToJsonString: string;
  class function FromJsonString(AJsonString: string): TRedeemItemsClass;
end;

implementation

function TRedeemItemsClass.ToJsonString: string;
begin
  result := TJson.ObjectToJsonString(self);
end;

class function TRedeemItemsClass.FromJsonString(AJsonString: string): TRedeemItemsClass;
begin
  result := TJson.JsonToObject<TRedeemItemsClass>(AJsonString)
end;

jObj := TJSONObject.ParseJSONValue(TEncoding.ASCII.GetBytes(reqRedeem.ToJsonString), 0) as TJSONObject;

Using this line of code I get my json request string like

{"RedeemCode":"","AssetKey":"xxxxx"}

as expected.

Redeem request body json string should either one of these ( according to information received from the customer assetkey or redeemcode)

{"RedeemItems":[{"AssetKey":"xxxxx"}]}

or

{"RedeemItems":[{"RedeemCode":"xxxxx"}]}

So in the short term, I want to ignore all fields (including arrays) that is empty or nil.

I'm using Delphi 10 Seattle.

You have to build the JSON "by hand" or write an interceptor for this — Sir Rufo
– Sir Rufo, Commented Feb 15, 2016 at 16:36
Check out this question: stackoverflow.com/questions/12168982/json-empty-array — Machado
– Machado, Commented Feb 15, 2016 at 19:51

T.S · Accepted Answer · 2021-04-22 06:05:00Z

2

You can use the below method:

function TRedeemItemsClass.ToJsonString: string;
begin
  result := TJson.ObjectToJsonString(self, [TJsonOption.joIgnoreEmptyStrings]);
end;

or

function TRedeemItemsClass.ToJsonObject: TJSONObject;
begin
  result := TJson.ObjectToJsonObject(self, [TJsonOption.joIgnoreEmptyStrings]);
end;

edited Apr 22, 2021 at 6:05

T.S

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answered Aug 28, 2017 at 18:41

Cleidson Barbosa

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Comments

Machado · Accepted Answer · 2016-02-26 17:27:04Z

0

You can simply check it's nil condition:

if Assigned(field) then
begin
  // do something
end;

or

if field <> nil then
begin
  // do something
end;

answered Feb 26, 2016 at 17:27

Machado

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