[Component] [select]: select 配置可清空功能，清空后值变成undefined，类型发生变化

[xingyixiang]

Bug Type: Component

Environment

• Vue Version: 3.4.21
• Element Plus Version: 2.7.3
• Browser / OS: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36
• Build Tool: Vite

Reproduction

Related Component

• el-select

Reproduction Link

Element Plus Playground

Steps to reproduce

下拉选择后点击清空按钮

What is Expected?

绑定的值还是string类型，值变成空字符串

What is actually happening?

值变成undefined

Additional comments

[warmthsea]

https://github.com/element-plus/element-plus/blob/b1bfb9fd1b52265ffd7737f4e9d81e0ac99c17d6/packages/hooks/use-empty-values/index.ts#L39C1-L51C5

It seems to be here.

[warmthsea]

You can set :value-on-clear

[xingyixiang]

@warmthsea @kooriookami I understand that the default should be set to an empty string so that there are no breaking changes.

[btea]

@xingyixiang The current effect should be the same as before 2.7.0. To meet your requirements, configuring value-on-clear as @warmthsea suggested should be enough.

Or did I misunderstand what you meant? 🤔

[warmthsea]

clearable after:

2.56: (<2.60) old value type
2.60: undefined
2.70: undefined (add new attributes :value-on-clear)
🤔

[btea]

An adjustment made intentionally in version 2.6.0. #15995

[xingyixiang]

An adjustment made intentionally in version 2.6.0. #15995

If it's a long-term change, so be it.

[huhaoer]

https://github.com/element-plus/element-plus/blob/b1bfb9fd1b52265ffd7737f4e9d81e0ac99c17d6/packages/hooks/use-empty-values/index.ts#L39C1-L51C5

It seems to be here.

I also encountered this problem, thank you