[TextField] Remove inputClassName property

[kgregory]

Fixes #9508

For TextField, inputClassName should be applied to the input element whether InputProps includes inputProps or not. The one exception would be if the inner inputProps includes a className prop as well.

Breaking change

The existing InputProps property can be used to set the className on the input element, making inputClassName redundant. Issue #9508 exposed some conflicting behavior between the two properties and it was decided that removing inputClassName would result in a cleaner API.

-  /**
-   * The CSS class name of the `input` element.
-   */
-  inputClassName: PropTypes.string,

The configuration of the wrapped Input component and its input element should be done through InputProps. To specify a className on the input element:

<TextField InputProps={{ inputProps: { className: 'foo' } }} />

[oliviertassinari]

Maybe the solution is to remove inputClassName

[kgregory]

@oliviertassinari that would be cleaner. If that's the consensus, I'll update the PR.

[rosskevin]

I debated removing inputClassName before. On TextField, it is flatly exposing a field that is propagated to a great grandchild, and it is ultimately className. I really wonder about these convenience props when we have the uppercase Component props. It's hard to determine where the line is.

But, I do know where I stand, and that is with clarity. I would kill all of these synthetic props and only allow you to pass via the upper case component props itself. I'm sure I could be convinced to expose things for high use scenarios, but otherwise anything advanced should just be through the upper case component props.

[kgregory]

@rosskevin I agree with you. InputProps should be enough for TextField. inputProps should be enough for Input. The subset of input attributes that have been added to both of these components is incomplete and will always cause confusion. Maybe some have merit, like name, but I share your stance on this.

[oliviertassinari]

@kgregory Sounds like we have a plan. You can make the PR much simpler by removing inputClassName. A breaking change section like here would be perfect for when we edit the release note.

[oliviertassinari]

Let's make things simpler :)

[kgregory]

@oliviertassinari all set, thanks again.

[oliviertassinari]

It's perfect 👌