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8222 :: How can I tell Nim that a JsObject has some certain attributes?

• halloleo (orginal) [2021-07-12T08:22:55+02:00] view original

  In an external file I have a JavaScript function like this:

  
  function getInfo(){
      return {data : "Hallo", code : 42};
  }
  Run

  How can I call the object attributes/keys data and code in Nim? I tried the dot operator from jsffi:

  import jsffi
  
  proc getInfo(): JsObject {.importc.}
  
  let kvRes = getInfo()
  echo kvRes.data
  Run

  but I always get a compile error "_Error: type mismatch: got <JsObject> but expected one of:..._".

  Do I somehow have to tell Nim what attributes/keys the JsObject has? And how can I do this? Theer must be a way via jsffi...

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• ynfle (orginal) [2021-07-12T08:44:07+02:00] view original

  I don't think the issue is the fact that Is doesn't have that key as it's getting a type mismatch.

  Can you post the rest of the error message? Which part of the code is erroring?

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• DeletedUser (orginal) [2021-07-12T09:00:31+02:00] view original

  type InfoObject = ref object # ref object mirrors JS object semantics data: cstring code: int proc getInfo(): InfoObject {.importc.} let kvRes = getInfo() echo $kvRes.data

  Run

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• halloleo (orginal) [2021-07-12T09:42:34+02:00] view original

  Using an explicit type is my preferred solution - and your code works. Thanks!

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