英文:
Type 'string' is not assignable to type - How to type an object in array?
问题
我有一个长数组：
const allRoles = {'product_manager': [{id: 'productManager_1',image: '/icon.png',title: 'CEO of the product',description: 'Some description.</>',},'backend_engineer': [{...}]...}
组件代码：
// roleTitle = "Product Manager"export function OverviewModal(roleTitle: string) {const convertedRole: keyof typeof allRoles = roleTitle.toLowerCase().replace(/ /g,'_');const roleCardInfo = allRoles[convertedRole];// Tried the above but got an error:// Type 'string' is not assignable to type '"product_manager" | "backend_engineer"...'.ts(2322)
在这种情况下，这似乎不适用：
https://stackoverflow.com/questions/37978528/typescript-type-string-is-not-assignable-to-type
与类不同，我只有一个数组对象。在这种情况下，我不确定它的类型是什么。
英文:
I have a long array:
const allRoles = {'product_manager': [{id: 'productManager_1',image: '/icon.png',title: 'CEO of the product',description: 'Some description'.</>,},'backend_engineer': [{...}]...}
Component code:
// roleTitle = "Product Manager"export function OverviewModal(roleTitle: string) {const convertedRole: keyof typeof allRoles = roleTitle.toLowerCase().replace(/ /g,'_');const roleCardInfo = allRoles[convertedRole];// Tried the above but got an error:// Type 'string' is not assignable to type '"product_manager" | "backend_engineer"...'.ts(2322)
In this case, this doesn't seem to apply:
https://stackoverflow.com/questions/37978528/typescript-type-string-is-not-assignable-to-type
Instead of a class, I just have an object of arrays. I'm not sure what type it would be in this scenario.
答案1
得分: 1
这一部分你实际上在说 convertedRole 应该是 allRoles 的某个键。
const convertedRole: keyof typeof allRoles
allRoles 的类型是你传递给它的值的形状。而你已经声明了你的参数 roleTitle 是一个字符串。所以字符串不是足够狭窄的类型来赋给 convertedRole。convertedRole 只能被分配等于 allRoles 类型的键的字符串，也就是字符串 "product_manager" | "backend_engineer"...
请记住，TypeScript 不存在于运行时。它无法知道在运行代码时 roleTitle 的实际值。
英文:
So at this part you are literally saying that convertedRole should be some key of allRoles.
const convertedRole: keyof typeof allRoles
the type of allRoles is the shape of the value you are giving it. And you have declared your argument roleTitle as a string. So a string is not narrow enough a type for convertedRole. convertedRole can only be assigned strings that are equal to the keys of the type of allRoles, aka the strings "product_manager" | "backend_engineer"...'.
Remember that typescript does not exist in runtime. It can not know the actual value of roleTitle as you run the code.
答案2
得分: 1
Cengen 是对的。
但是，如果您能够在编译时知道 AllRoles 的键，可能会有解决方案，就像这样：
const roleTypeNames = ['product_manager', 'backend_engineer'] as const;type roleType = typeof roleTypeNames[number]const allRoles: { [key in roleType]: any } = { ... };
如果是的话，那么您可以使用类型保护。
const isRoleType = (candidate: string): candidate is roleType => {for (const role of roleTypeNames) {if (role === candidate) return true;}return false;}function OverviewModal(roleTitle: string) {const sanitizedRoleTitle = roleTitle.toLowerCase().replace(/ /g, '_');if (isRoleType(sanitizedRoleTitle)) {const roleCardInfo = allRoles[sanitizedRoleTitle];}}
英文:
Cengen is right.
But, may you would have a solution to your problem if you were able to know at compile time the key of AllRoles like this :
const roleTypeNames = ['product_manager','backend_engineer'] as const;type roleType = typeof roleTypeNames[number]const allRoles : {[key in roleType]:any} = { ... };
if yes, then you can use a typeguard.
const isRoleType = (candidate : string) : candidate is roleType => {for(const role of roleTypeNames){if(role === candidate) return true ;}return false;}function OverviewModal(roleTitle: string) {const sanitizedRoleTitle = roleTitle.toLowerCase().replace(/ /g,'_');if(isRoleType(sanitizedRoleTitle)){const roleCardInfo = allRoles[sanitizedRoleTitle];}}
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