Cloud Functions: Values not read in Map

Question

Why am I unable to read the following variables in a nested map?

for (const key in doc.data().category) {
  const location = doc.data().location;  // declared but it's value is never read"
  const mainCategory = doc.data().category; // declared but it's value is never read"
  const subCategory = doc.data().category[key]; // declared but it's value is never read"

  categoryCount.doc('categoryCount')
  .set({ location: { mainCategory: { subCategory: "test" } } }, 
  { merge: true })
  .catch((error) => console.log(error));

Console logs to clarify:

console.log(location); // "New York"
const map = { location: { mainCategory: { subCategory: true } } };
console.log(map);  // "location": {"mainCategory": {"subCategory": true}}

I'm having a hard time understanding what the problem is. What do you mean by "declared but it's value never read"? — Doug Stevenson, Dec 02 '19 at 17:27
@DougStevenson I've added console logs to clarify. I can't get the values when using the variables in a map. The TSLint error is "declared but it's value is never read". — Mr Jax, Dec 02 '19 at 17:44
What do you expect the code to do instead of what it's doing now? — Doug Stevenson, Dec 02 '19 at 17:50
@DougStevenson Return the actual data of the variable, not variable name. So, return "New York": {"Running": {"Race":true}}, instead of "location": {"mainCategory": {"subCategory": true}} — Mr Jax, Dec 02 '19 at 17:56

score 2 · Accepted Answer · answered Dec 02 '19 at 17:58

2

If you want to use the value of a variable as the name of a property, you have to tell JavaScript that you want to insert that value (as opposed to just naming the key):

{ [location]: { mainCategory: { subCategory: "test" } } }

Notice the square brackets around location.

See also: Square Brackets Javascript Object Key

answered Dec 02 '19 at 17:58

Doug Stevenson

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Ah ok! I didn't know that - it's working now. Thanks so much :) Really appreciate it – Mr Jax Dec 02 '19 at 18:07

score 0 · Answer 2 · answered Dec 02 '19 at 17:57

I think you may be misunderstanding how JavaScript objects work. Imagine you have three variables called:

var A = 'X';
var B = 'Y';
var C = 'Z';

when you code:

{
  A: {
    B: {
      C: "test"
    }
  }
}

You do not end up with an object of value:

{
   X: {
     Y: {
       Z: "test"
     }
   }
}

If that is what you want, consider:

var O1 = {};
O1[C] = "test";
var O2 = {};
O2[B] = O1;
var O3 = {};
O3[A] = O2;

// O3 is the top level object

Cloud Functions: Values not read in Map

2 Answers2