This is based on http://blog.synopse.info/post/2014/02/25/TDocVariant-custom-variant-type and the corresponding forum http://synopse.info/forum/viewtopic.php?id=1631
Create
A TDocVariant custom variant type is declared as a Variant:
var LDocVariant : Variant;
The TDocVariant can be created as an object or from a JSON string. You can use the _Obj/_ObjFast, _JSON/_JSONFast and _Arr/_ArrFast methods to create the TDocVariant.
LDocVariant := _ObjFast( [ 'name', 'bernd' ] );
LDocVariant := _JsonFast( '{ "Person": { "First" : { "name" : "bernd" } } }' );
LDocVariant := _ArrFast( [ _ObjFast( [ 'name', 'bernd' ] ),
_ObjFast( [ 'name', 'bob' ] ) ] );
Read
You can access items in the TDocVariant variable dynamically:
Writeln( LDocVariant.name ); Writeln( LDocVariant.Person.First.Name ) Writeln( LDocVariant._(0).name );
Each of these will output “bernd”.
A TDocVariant will also be cast as JSON string when used in place of a string, for example, using the examples above, calling the following on each respectively:
Writeln( LDocVariant );
will output the following:
{"name":"bernd"}
{"Person":{"First":"bernd"}}
[{"name":"bernd"},{"name":"bob"}]
For arrays you also have _Count so you can iterate through the array:
for LIndex := 0 to LDocVariant._Count - 1 do Writeln( LDocVariant._(LIndex).name );
Update
Updating items and properties is really easy:
LDocVariant.name := "Bernd"; LDocVariant.Person.First.name := "Bernd"; LDocVariant._(1).name := "Bob";
You can add objects, array items or values to existing items as well.
LDocVariant.age := 31; LDocVariant.Person.Next := _ObjFast( ['name','bob'] ); LDocVariant.Person.Next.age = 43; LDocVariant.Add( _ObjFast( [ 'name', 'ned' ] ) );
Delete
All TDocVariant variables have the Delete method to remove an item from the object or array:
LDocVariant.Delete( 'name' ); LDocVariant.Person.Delete( 'Next' ); LDocVariant.Delete( 1 );