TextInput defaultValue with a function does not work

[edulix]

What you were expecting:
Setting a defaultValue={() => uuid()} to a TextInput should work. I'm creating an UuuidInput field, that should by default provide a new uuid. It works if the SimpleForm sets an initialValues function, but that's not what I need.

What happened instead:
The TextInput appears empty inside the SimpleForm.

Steps to reproduce:
Use a SimpleForm with a TextInput

Related code:
Take a look at https://codesandbox.io/s/intelligent-bartik-km7ed?file=/src/posts/PostCreate.js

I modified the forked default code sandbox so that he create post form has a title TextInput field with a string defaultValue and teaser field has a functional defaultValue property. The title works, the teaser field appears empty:

        <TextInput autoFocus source="title" defaultValue="static value" />
        <TextInput
          source="teaser"
          defaultValue={() => "value from a function"}
        />

Environment

• React-admin version:3.9.0
• Last version that did not exhibit the issue (if applicable): -
• React version: 16.9.0
• Browser: chrome
• Stack trace (in case of a JS error): -

[fzaninotto]

Reproduced, thanks.

Looking at the react-admin code, this regression seems to be caused by the FormWithRedirect refactoring this regression was caused by the move from redux-form to react-final-form (in 306aef5, released in 3.0, more than a year ago). However, reintroducing this feature (which was introduced by #277 and is documented in CreateEdit.md#per-input-default-value) isn't trivial, and besides it never really worked: we had to inspect Form children, which was never robust.

I think this should be a react-final-form feature, and making it work outside of that lib is too risky.

So I think what we should do here is fix the documentation to remove the ability to pass a custom function as default value.

In your case, you can use the form initialValues to set the initial value for one field at the form level.