英文:
Unable to type function to retrieve values from nested objects using array values
问题
I understand your request. Here is the translated code and error message:
// 嵌套对象
const obj = {
one: {
two: {
three: 'xxxx',
},
four: {
five: 5,
},
six: [1, 2, 3],
},
}
// 我想要使用键从上面的嵌套对象中获取一个值。
// 下面的示例在JavaScript中工作，但我无法正确定义TypeScript中的类型。
const result = ['one', 'two', 'four'].reduce(
(acc, key) => acc[key],
obj,
)
// undefined
const result = ['one', 'two', 'three'].reduce(
(acc, key) => acc[key],
obj,
)
// xxxx
const result = ['one', 'six'].reduce(
(acc, key) => acc[key],
obj,
)
// [1, 2, 3]
tslint：
由于类型“string”的表达式不能用于类型为“{ one: { two: { three: string; }; four: { five: number; }; six: number[]; }; }”的对象的索引，因此“element”隐含具有“any”类型。
在类型“{ one: { two: { three: string; }; four: { five: number; }; six: number[]; }; }”上找不到参数类型为“string”的索引签名。ts(7053)
我理解类型检查不起作用，因为数组中的“one”是一个字符串，而reduce中的键是“one”。
然而，我想不出一个解决方案。
请告诉我哪种类型定义会起作用。
如果您需要进一步的帮助，请告诉我。
英文:
// nested object
const obj = {
one: {
two: {
three: 'xxxx',
},
four: {
five: 5,
},
six: [1, 2, 3],
},
}
I want to get a value from the above nested object using key.
The sample below works in javascript, but I can't define the type properly in typescript.
const result = ['one', 'two', 'four'].reduce(
(acc, key) => acc[key],
obj,
)
// undefined
const result = ['one', 'two', 'three'].reduce(
(acc, key) => acc[key],
obj,
)
// xxxx
const result = ['one', 'six'].reduce(
(acc, key) => acc[key],
obj,
)
//  [1, 2, 3]
tslint
Element implicitly has an 'any' type because expression of type 'string' can't be used to index type '{ one: { two: { three: string; }; four: { five: number; }; six: number[]; }; }'.
No index signature with a parameter of type 'string' was found on type '{ one: { two: { three: string; }; four: { five: number; }; six: number[]; }; }'.ts(7053)
I understand that the type checking does not work because "one" in the array is a string and the key from reduce is "one".
However, I can't think of a solution.
Please let me know what type definition would work.
答案1
得分: 1
If you defined a type which is a record with a string key and any value:
定义了一个具有字符串键和任意值的记录类型：
type kv = Record<string, any>;
Then your original object is itself a record with a string key, and either another kv or any value:
然后你的原始对象本身是一个具有字符串键的记录，要么是另一个 `kv` 类型，要么是 `any` 类型的值：
const obj: Record<string, kv | any> = {
one: {
two: {
three: 'xxxx',
},
four: {
five: 5,
},
six: [1, 2, 3],
},
}
Then your warnings go away Live example
然后你的警告消失了。【在线示例链接】
英文:
If you defined a type which is a record with a string key and any value:
type kv = Record<string,any>;
Then your original object is itself a record with a string key, and either another kv or any value:
const obj : Record<string, kv | any> = {
one: {
two: {
three: 'xxxx',
},
four: {
five: 5,
},
six: [1, 2, 3],
},
}
Then your warnings go away Live example
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