Question

Please refer to this example.我需要扩展自动生成的，不可更改的类型。在阵列方面我遇到了麻烦：

// Auto created and imported object.
// Cannot be changed.
// Should be extended
type Drinks = {
  // many other stuff
  beers: Array<{
    brand: string
  }>
}

type ExtendedBeer = {
  size: number
}

type DrinksExtended = Drinks & {beers: Array<ExtendedBeer>} // Throws

const myDrink: DrinksExtended = {
  beers: [{brand: 'Rothaus', size: 0.5}]                            
}

myDrink.beers.map(beer => beer.size) // Throws: `size`. Property not found

Answer 1

似乎流不支持泛型中的那种对象类型的交集。

此示例按预期工作

type beerWithBrand = {
    brand: string
}

type beerWithSize = {
    size: number
}

type beerStock = {
    beers: Array<beerWithBrand & beerWithSize> 
}

var stock : beerStock = {beers : [{brand: 'Rothhaus', size: 0.5}]}

编辑：这是预期的行为，因为Array类型的性质（可变）。见https://github.com/facebook/flow/issues/4258

如何在数组上使用Flow Intersection Types来扩展自动生成的类型？

1 个答案: