My goal is to connect to Firebase, retrieve data from a specified location, loop through the fetched data using snapshot.val() and build an Array. Then I plan to return this Array and loop through it in component.html to create a Dropdown.
I am currently struggling with the syntax for implementing such a service method. Below is my existing code that is called from ngOnInit() in app.component.ts:
getExerciseOptions(): Array<Exercise> {
const items: Exercise[] = [];
this.exerciseDbRef2.on("value", (snapshot) => {
snapshot.forEach((snap) => {
items.push({
id: snap.key,
description: snap.val().description
});
return false;
});
});
}
The reference this.exerciseDbRef2 points to the Firebase table as defined below:
private exerciseDbRef2 = this.fire.database.ref('/exercise_description');
The error message I am encountering states:
A function whose declared type is neither 'void' nor 'any' must return a value.
When I change return false to return items, I receive the following new error:
Argument of type '(snap: DataSnapshot) => Exercise[]' is not assignable to parameter of type '(a: DataSnapshot) => boolean'.
Type 'Exercise[]' is not assignable to type 'boolean'.
I have considered using child_added, but I believe this event would trigger every time a new child is added to the location, which is not the behavior I desire. The children within this location will remain constant without any additions. Perhaps I misunderstood the purpose of 'child_added'?
As I am relatively new to utilizing Firebase, I appreciate your patience as I navigate the learning curve. If you identify any flaws in my current approach, please feel free to point them out.
In summary: Connect to Firebase, fetch all children from the specified location (i.e., exercise_description table), iterate through the snapshot, construct an Array, and return it.
Subsequently, within the component, loop through the Array to generate the Dropdown.
Could someone kindly provide guidance on how to effectively return the Array based on the data obtained from snapshot.val()?