Extract all object properties paths as string arrays | TypeScript Community | Page 1

graceful thicket Aug 22, 2024, 9:01 PM

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Basically I am trying to get all Object properties as string array paths, so i would have ["home"] as a valid path and ["settings"] and ["settings", "workflows", "create"]
etc.

Here is my attempt, can someone help me fix the generic? https://www.typescriptlang.org/play/?#code/MYewdgzgLgBADgQygCwjAvDA3gKBjZEAWwFMAubAXwBo8YISooBLMAcwgt33wFcGATpyq0eMASAA2kkLyjCsNOvgDuIAQGsAZjJUKYwASSTkqMJWODISwDZObR9h41FOLzongHJg-KMQBaLWYSSQATCC8uC29gexIwKAD7MA1I6M98Vlc2ASRmcAUYpUoYBDRQSCgAbhwoAE84EhgAJQQVAAUkVAwYBqaQLXhuiFq6xuaAUQAPKDzgKC6UCAAeOkQUGBJZhIj6OdY2AG0AXU8QACMAKy2dsD3FTw0SetvXe7Rn+sGYS5vML4-P60AB8vQ2yBgAB8YDM5ggFktUCsjgA6dEQ6gwL5nX7XI44kHVIA

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crisp narwhalBOT Aug 22, 2024, 9:01 PM

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@graceful thicket Here's a shortened URL of your playground link! You can remove the full link from your message.

autumnlight#0

Playground Link

Preview:ts const paths = { home: {}, settings: { users: {}, rollouts: {}, workflows: {create: {}}, checklists: {create: {}}, "custom-fields": {}, "client-links": {}, integrations: {}, }, } as const type RawPaths = typeof paths ...

junior star Aug 22, 2024, 9:05 PM

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Do you want the result as a union?

graceful thicket Aug 22, 2024, 9:06 PM

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yeah

graceful thicket Aug 22, 2024, 9:06 PM

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junior star Do you want the result as a union?

that is indeed my coal

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its a parameter for a function, so i know which route the user tries to invoke

crisp narwhalBOT Aug 22, 2024, 9:09 PM

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const paths = {
  home: {},
  settings: {
    users: {},
    rollouts: {},
    workflows: { create: {} },
    checklists: { create: {} },
    'custom-fields': {},
    'client-links': {},
    integrations: {},
  },
} as const;
type RawPaths = typeof paths;

type ExtractPaths<O extends Record<string, unknown>> = keyof O extends infer K extends string ?
  K extends infer K extends string
    ? [K]
    : never
  : never

type Paths = ExtractPaths<typeof paths>
//   ^? - type Paths = ["home"] | ["settings"]

junior star Aug 22, 2024, 9:09 PM

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that's the first level, right?

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the extends stuff is just to distribute the keyof union

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then you just need to replace [K] with a O[K] extends Record<string, unknown> and use recursion to build out the full tuple, I think

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type ExtractPaths<O extends Record<string, unknown>> = keyof O extends infer K extends string ?
  K extends infer K extends string
    ? O[K] extends Record<string, unknown>
      ? [K, ...ExtractPaths<>]
      : [K]
    : never
  : never

the spread operator there lets you combine the sub path with the first part to make a complete tuple

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weird, it breaks for some reason 😄

graceful thicket Aug 22, 2024, 9:13 PM

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junior star ```ts type ExtractPaths<O extends Record<string, unknown>> = keyof O extends inf...

this seems to not work, even if add O[K] it falls back to never

junior star Aug 22, 2024, 9:13 PM

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Yeah it's odd

graceful thicket Aug 22, 2024, 9:13 PM

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why do you even do :never?

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I think it's simpelr to do it with two generics

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Ohh, I see what you're doing

junior star Aug 22, 2024, 9:15 PM

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Maybe it's because eventually you get to the leaf node and then the recursion fails?

graceful thicket Aug 22, 2024, 9:15 PM

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i removed all nevers and it still returns never

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i replaced the nested one with K and outer one with []

junior star Aug 22, 2024, 9:16 PM

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type ExtractPaths<O extends Record<string, unknown>> = keyof O extends infer K extends string ?
  K extends infer K extends string
    ? O[K] extends Record<string, unknown>
      ? [K, ExtractPaths<O[K]>]
      : [K]
    : never
  : never

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try this

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it nearly works

graceful thicket Aug 22, 2024, 9:18 PM

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im also trying around

junior star Aug 22, 2024, 9:19 PM

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type ExtractPaths<O extends Record<string, unknown>> = keyof O extends infer K extends string ?
  K extends infer K extends string
    ? O[K] extends Record<string, unknown>
      ? [K, ExtractPaths<O[K]>]
      : [K]
    : 'blah'
  : 'blah'


type T = ExtractPaths<{}>

T here is never, so I think addressing that is the answer

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If that can be [] I think it works?

graceful thicket Aug 22, 2024, 9:20 PM

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yeah, I dont get from where we get never in the first place

junior star Aug 22, 2024, 9:20 PM

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or am I being dumb because we're returning a union not a tuple so we can't spread it?

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instead of [K, ...ExtractPaths<O[K]>] we need to be distributing over ExtractPaths<O[K]> so we return a union of all the possibilities

graceful thicket Aug 22, 2024, 9:21 PM

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im not this good in ts to talk with you, i can be a rubber duck at most lol

junior star Aug 22, 2024, 9:22 PM

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keyof {} is never, so that's probably where the never comes from

junior star Aug 22, 2024, 9:22 PM

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graceful thicket im not this good in ts to talk with you, i can be a rubber duck at most lol

Time to learn LOL

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So when it distributes never, it result is never

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So this means we need to use ExtractPaths<O[K]>, check for never, if so return [K] otherwise distribute over the result, and then thinking about whether it works for 3 levels

graceful thicket Aug 22, 2024, 9:32 PM

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got it

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i think

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type ExtractPaths2<
  path extends string[],
  Obj extends Record<string, {}>,
> = Obj extends {[key:string]:never} ? path : ExtractPaths2<[...path, `${Extract<keyof Obj, string>}`], Obj[Extract<keyof Obj, string>]>;

junior star Aug 22, 2024, 9:32 PM

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does it work?

graceful thicket Aug 22, 2024, 9:33 PM

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seems to

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lemme check

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yes

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it does

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blobcool

graceful thicket Aug 22, 2024, 9:33 PM

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junior star does it work?

sorry for not using your solution, its way too difficult for me to understand Skull

junior star Aug 22, 2024, 9:34 PM

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simple is good

graceful thicket Aug 22, 2024, 9:34 PM

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im further optimizing rn

junior star Aug 22, 2024, 9:34 PM

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What types are you passing to your function?

crisp narwhalBOT Aug 22, 2024, 9:35 PM

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autumnlight#0

Playground Link

Preview:ts const paths = { home: {}, settings: { users: {}, rollouts: {}, workflows: {create: {}}, checklists: {create: {}}, "custom-fields": {}, "client-links": {}, integrations: {}, }, } as const type RawPaths = typeof paths ...

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sandiford#0

Playground Link

Preview:ts const paths = { home: {}, settings: { users: {}, rollouts: {}, workflows: {create: {}}, checklists: {create: {}}, "custom-fields": {}, "client-links": {}, integrations: {}, }, } as const type RawPaths = typeof paths ...

junior star Aug 22, 2024, 9:36 PM

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I don't think that is correct

graceful thicket Aug 22, 2024, 9:36 PM

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aww dawn

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sec

graceful thicket Aug 22, 2024, 9:37 PM

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junior star I don't think that is correct

my issue is, i dont know how to extract the key and use it properly

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basically i need to extract the key on the left and use it on the right

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once i did that it will work

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but i dont know how

junior star Aug 22, 2024, 9:38 PM

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?

graceful thicket Aug 22, 2024, 9:40 PM

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@junior star

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basically if i can get these two to be equal it will work

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thats where im stuck

junior star Aug 22, 2024, 9:40 PM

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they they are both unions right?

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so you need to distribute

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!hb dist

crisp narwhalBOT Aug 22, 2024, 9:41 PM

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Handbook / Conditional Types

Distributive Conditional Types

graceful thicket Aug 22, 2024, 9:41 PM

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yeah, basically before I get intro extract path i need to iterate over te keys

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OH

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wait

junior star Aug 22, 2024, 9:41 PM

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You cand do this to iterate keyof Obj extends K extends string ? K extends infer K extends string ? ... : never : never

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and you will get a union of the results

crisp narwhalBOT Aug 22, 2024, 9:43 PM

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const paths = {
  foo: 'b',
  home: {},
  settings: {
    users: {},
    rollouts: {},
    workflows: { create: {} },
    checklists: { create: {} },
    'custom-fields': {},
    'client-links': {},
    integrations: {},
  },
} as const;
type RawPaths = typeof paths;

type ExtractPaths<O extends Record<string, unknown>> = keyof O extends infer K extends string
  ? K extends infer K extends string
    ? O[K] extends Record<string, unknown>
      ? ExtractPaths<O[K]> extends infer R extends readonly string[]
        ? [R] extends never[]
          ? [K]
          : [K, ...R]
        : 'n/a'
      : [K]
    : 'n/a'
  : 'n/a'

type Paths = ExtractPaths<typeof paths>
//   ^? - type Paths = ["foo"] | ["home"] | ["settings", "users"] | ["settings", "rollouts"] | ["settings", "workflows", "create"] | ["settings", "checklists", "create"] | ["settings", "custom-fields"] | [...] | [...]

junior star Aug 22, 2024, 9:44 PM

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I was really struggling because if you do never extends never ? : you get no result, because distributing never is distributing into 0 iterations

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lol

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but [never] extends [never] is ok

graceful thicket Aug 22, 2024, 9:44 PM

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ahh

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but generally

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a question

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How can I here pull the Key into a variable or something and then use it in both extractPaths argument?

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there has to be a way

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but I dont know it

junior star Aug 22, 2024, 9:48 PM

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I just told you, distribution

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You don't want T = 'a' | 'b' | 'c' and G<T, T> right because it gives you a big messy union?

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if you do G<T> = T extends string ? T : never, then its going to iterate over T and return each result into a union

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In that case you break apart the union and then recombine it, so it does nothing much

crisp narwhalBOT Aug 22, 2024, 9:52 PM

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type G1<T extends string> = (T|null)[]
type G2<T extends string> = T extends string ? (T|null)[] : never

type R1 = G1<'foo' | 'bar'>
//   ^? - type R1 = ("foo" | "bar" | null)[]
type R2 = G2<'foo' | 'bar'>
//   ^? - type R2 = ("foo" | null)[] | ("bar" | null)[]

graceful thicket Aug 22, 2024, 9:52 PM

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junior star You don't want T = 'a' | 'b' | 'c' and G<T, T> right because it gives you a big ...

its more that I am trying to understand why my solution fails

junior star Aug 22, 2024, 9:52 PM

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compare the difference

graceful thicket Aug 22, 2024, 9:52 PM

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and trying to get that to work

junior star Aug 22, 2024, 9:52 PM

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And I'm replying to that

graceful thicket Aug 22, 2024, 9:54 PM

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ohh

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https://www.typescriptlang.org/play/?#code/MYewdgzgLgBADgQygCwjAvDA3gKBjZEAWwFMAubAXwBo8YISooBLMAcwgt33wFcGATpyq0eMASAA2kkLyjCsNOvgDuIAQGsAZjJUKYwASSTkqMJWODISwDZObR9h41FOLzongHJg-KMQBaLWYSSQATCC8uC29gexIwKAD7MA1I6M98Vlc2ASRmcAUYpUoYBDRQSCgAbhwoAE84EhgAJQQVAAUkVAwYBqaQLXhuiFqcOsbmgFEADyg84CgAZV4AIwAeOkQUGBI5hIj6edY2AG0AXU8AeVWAK139sEOsU40SerJoARPzskUYgDS7werieaDe9UGMBu90wEKhMJwAD5ejCQQc0C8IZ9juxfmASAA3EgCUoAfmGOwos3mCEWKw2pwAdCztshqDSFlB1kD6tQjt92EjLtC7qdeeckWN+s0uig0JhOXTlmt1hdqG1OiMkeNKtAYFoIAgyHKephTgAiBhME4QC3UC0WmDnHBAA could you try to fix this variant?

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crisp narwhalBOT Aug 22, 2024, 9:55 PM

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@graceful thicket Here's a shortened URL of your playground link! You can remove the full link from your message.

autumnlight#0

Playground Link

Preview:ts const paths = { home: {}, settings: { users: {}, rollouts: {}, workflows: {create: {}}, checklists: {create: {}}, "custom-fields": {}, "client-links": {}, integrations: {}, }, } as const type RawPaths = typeof paths ...

graceful thicket Aug 22, 2024, 9:55 PM

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i am getting nthe first level

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but its not going further

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Oh

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wait

junior star Aug 22, 2024, 9:57 PM

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your approach is confusing me haha

graceful thicket Aug 22, 2024, 9:58 PM

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different mindset i assume

junior star Aug 22, 2024, 9:58 PM

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So do you notice that type Paths = ["home" | "settings"] is incorrect?

graceful thicket Aug 22, 2024, 9:59 PM

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oh wait

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i did not notice

junior star Aug 22, 2024, 9:59 PM

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I mean technically it is correct in a simple case, but you really want ["home"] | ["settings"]

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because once you add the 2nd level, they need to be separate

graceful thicket Aug 22, 2024, 10:00 PM

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I am a bit confused on why its not an union

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im too tired

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i should go to bed

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thank you for your help

junior star Aug 22, 2024, 10:02 PM

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I think as a practice you should work on this challenge
https://www.typescriptlang.org/play/?#code/MYewdgzgLgBADgQygCwjAvDA3gKBjZEAWwFMAuGKAJwFcSAaPGCEqASzAHMILq6cAvjARpQkKAG4cUAJ5wSMAEoIA7gAUkqDJTkkQAM3iaIU6bpgBRAB7UEwKBpQQAPAHkARgCsYJGyTAAJmhYAgB82gDaANYkMgYwHp4AujA4OAD06TAAwsgIADb5-pzkMEQIMTAAKjAcUCAwEQBEhKRNKQA+jU0sUOxcEO1psvLV2ta29o6ozsrqxqEZWfgAegD8QA

TS Playground - An online editor for exploring TypeScript and JavaS...

The Playground lets you write TypeScript or JavaScript online in a safe and sharable way.

crisp narwhalBOT Aug 22, 2024, 10:02 PM

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@junior star Here's a shortened URL of your playground link! You can remove the full link from your message.

sandiford#0

Playground Link

Preview:```ts
const paths = {
home: true,
setings: true,
} as const
type RawPaths = typeof paths

type ExtractPaths<Obj extends {}> = [keyof Obj]

// Challenge: make T into ["home"] | ["settings"]

type T = ExtractPaths<RawPaths>
// ^?```

junior star Aug 22, 2024, 10:02 PM

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Also I solved the problem a while ago if you didn't see, using my approach

graceful thicket Aug 22, 2024, 10:02 PM

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i did see that, it was just that I wanted to figure out why mine failed

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lemme try this challenge

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type ExtractPaths<Obj extends {}> = [keyof Obj]
I would assume that it returns two arrays, I am confused on why its a union

junior star Aug 22, 2024, 10:03 PM

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keyof Obj is a union like 'a' | 'b'

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so this just says ['a' | 'b']

hardy jacinth Aug 22, 2024, 10:04 PM

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!:autopath

crisp narwhalBOT Aug 22, 2024, 10:04 PM

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tjjfvi#0

`!t6:autopath`: Playground Link

Preview:```ts
...
type User = {
id: string,
name: string,
age: number,
friends: User[],
parents: [User, User],
}

get(user, "friends.0") // returns User
get(user, "friends.0.age") // returns number
get(user, "this.does.not.exist") // error
get(user, "parents.3") // error, out of bounds

getString(user, "friends.0.id") // returns string
getString(user, "friends.0.age") // error, not a string```

hardy jacinth Aug 22, 2024, 10:04 PM

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couldnt you just modify this

graceful thicket Aug 22, 2024, 10:04 PM

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hardy jacinth couldnt you just modify this

we got a working solution, but im now in my process of learning

junior star Aug 22, 2024, 10:05 PM

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crisp narwhal ```ts const paths = { foo: 'b', home: {}, settings: { users: {}, r...

!snip paths-as-union-of-tuples

crisp narwhalBOT Aug 22, 2024, 10:05 PM

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:white_check_mark: Created snippet sandiford:paths-as-union-of-tuples

junior star Aug 22, 2024, 10:05 PM

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junior star so this just says `['a' | 'b']`

to make a union instead you need to distribute, which I linked you to already

hardy jacinth Aug 22, 2024, 10:05 PM

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graceful thicket type ExtractPaths<Obj extends {}> = [keyof Obj] I would assume that it returns...

it would be a union of arrays if it were distributed, but there's nothing triggering that here

junior star Aug 22, 2024, 10:05 PM

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confusingly distribution is trigger by extends clauses within generics

graceful thicket Aug 22, 2024, 10:06 PM

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im way too tired to learn this atm, ill take a look at it tmr, thank you ❤️

hardy jacinth Aug 22, 2024, 10:06 PM

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junior star confusingly distribution is trigger by extends clauses within generics

(*conditionals+mapped types over generics/infers)

twilit glade Aug 22, 2024, 10:14 PM

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Obligatory: are you sure you need this? Most places where these "array of string paths" things are used, you could use a callback property access instead.

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i.e. instead of doSomething(["foo", "bar", "baz"]) the API could be doSomething(x => x.foo.bar.baz)

#Extract all object properties paths as string arrays