Missing default value property in TextBox

I was looking a thread that shows how to put current user and current date in a textbox and then save them in a database.
It says to put current date in defaultvalue property of textbox.
But in my radzen editor for textbox I see only readonly / autocomplete / name / value / placeholder / visible / disabled / maxlength

Can you help me?

The string form field has a DefaultValue property. For the TextBox you have to use Value. If the Value is already set to some property then set that property to the current date/user.

But I need to save it to database, I now search string form field.

Ok I understood, with template form I have no string field I suppose.
My problem is I need to save current user and date when I save the form data to db.

Are you trying to achieve something like this? It shows how to persist the current user and date for all entities entirely from server-side code.

Otherwise check the data-bound template form section. It shows how to set default values for input elements that are then persisted to the database.

A third option exists too - to use a partial method and set the username and date there.