CODEWITHSUNDEEP
angulartypescript
Pri7
Pri7

Reputation: 11

Typescript: error TS2693: 'Note' only refers to a type, but is being used as a value here

I am trying to use Typescript for my firebase project and i am getting the following errors.

 error TS2693: 'Note' only refers to a type, but is being used as a value here.

I used the following code

interface Note {
 image: string;
 name: string;
 pdf: string;
}

const itemname = Note.name;

But that doesn't seem to work

here is the imports

import {
AngularFirestore,
AngularFirestoreCollection,
AngularFirestoreDocument,
} from '@angular/fire/firestore';
import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs';
import 'rxjs/add/operator/map';

here is the other part

  export class Advance11Component implements OnInit {
  notesCollection: AngularFirestoreCollection<Note>;
  notes: Observable<Note[]>;

  constructor(private afs: AngularFirestore) {}
  ngOnInit(): void {
  this.notesCollection = this.afs
    .collection('class11AdvancedTheory')
    .doc(itemname)
    .collection(itemname, (ref) => {
      return ref;
    });
    this.notes = this.notesCollection.valueChanges();
   }
  }

Upvotes: 0

Views: 13897

Answers (1)

Connor Low
Connor Low

Reputation: 7206

An interface (or type) can tell you the shape of something.

// A `tree` has a number of `branches`.
interface Tree {
  branches: number
}

An instance (e.g. const x = ...) assigns a specific value that can be reference at runtime.

// This `tree` has 34 `branches`.
const myTree: Tree = { branches: 34 }

You cannot mix these two during assignments. Taking your example, you would ask "How many branches does myTreeBranches have?" and it would say "typeof Tree.branches is number", information that is not useful or supported in JavaScript.

// Doesn't work
const myTreeBranches = Tree.branches // typeof `Tree.branches` is `number`.

You probably want one of these:

interface Tree {
    branches: number
}

type TreeBranches = Tree['branches'] // extract an interface property

const myTree: Tree = { branches: 34 } // create an instance of `Tree`

const myTreeBranches: Tree['branches'] = 34 // create variable that could be assigned to
                                            //    an instance of `Tree`

Upvotes: 2

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