DateField: initialValue not working when value is null

[thdk]

What you were expecting:
The DateInput component should use the value provided by the initialValue prop when the value is null or undefined.

As state in the docs for the DateInput component:

Prop	Required	Type	Default	Description
initialValue	Optional	mixed	-	Value to be set when the property is null or undefined

What happened instead:
When the value is null the DateInput ignores the value provided by the initialValue prop.
It does work however when the value is undefined the DateInput component correctly shows the value provided by the initialValue prop.

Steps to reproduce:

Related code:
I have forked the example sandbox and modified the data of the first two posts.
The first post now has null for date published.
The second post now has undefined for date published.

Next, I have adjusted the edit form for a post so that the published_at value now has an initialValue prop with a date.

<DateInput
            source="published_at"
            options={{ locale: "pt" }}
            initialValue={new Date(2100, 0, 1)}
 />

See the sandbox: https://codesandbox.io/s/compassionate-bush-s772t
Click the first post and open the misc. tab. See the value of the published field.
Expected: 01/01/2100
Actual: mm/dd/yyy

Click the second post and open the misc. tab. See the value of the published field.
Expected: 01/01/2100
Actual: 01/01/2100

Other information:

Environment

• React-admin version: 3.19.7
• Last version that did not exhibit the issue (if applicable): I believe 3.19.5
• React version: 17.0.0
• Browser: Version 97.0.4692.71 (Official Build) (64-bit)
• Stack trace (in case of a JS error): n/a

I have traced down the source code to the following line:

react-admin/packages/ra-core/src/form/useInput.ts

Line 78 in a1c602c

initialValue: get(record, source, initialValue),

Where lodash get method is used to get the value for a given property from the record object. However, this only returns the defaultValue if the actual value is 'undefined'. See docs for lodash get method.

[fzaninotto]

null and undefined don't mean the same thing in JS. We should only apply defaultValue if the value is undefined.

[WiXSL]

null and undefined don't mean the same thing in JS. We should only apply defaultValue if the value is undefined.

Of course, but as the bug report suggests, the documentation explicitly says Value to be set when the property is null or undefined
Maybe this can be taken as a documentation issue.

[fzaninotto]

yes, this is a documentation issue.