Iterating over an object from the database

Question

i'm doing project with angular and firebase. I get an object from firebase and I would like to display it in html, but I don't know how to get value from the object in the array. How can I iterate through auto indexes from the firebase ?

This is calls Firebase:

getListTasks() {
  return this.db.list('/Tasks').valueChanges();
}

This is my component:

this.taskService.getListTasks().subscribe(t => {
      this.todoTasks = t;
    });

This is my object in the array : https://i.stack.imgur.com/npowv.jpg

Hi @student_it -- could you post your Angular code and the code that calls Firebase. — , Oct 10 '19 at 11:25

score 1 · Accepted Answer · answered Oct 10 '19 at 12:30

You have to convert the object into an array for you to iterate over like below

  this.taskService.getListTasks().subscribe(tasks => {

  const tasksArray = Object.keys(tasks).map((key, index) => {
      const task = tasks[key];
      return task;
    });
    this.todoTasks = tasksArray;
  });

Angular also has a built in mechanism for doing this using the key-value pipe

I highly recommend this answer

JuNe · Answer 2 · 2019-10-10T12:26:08.493

0

Assuming that the todoTasks is an array, this is how you would implement.

<div *ngFor="let todo of todoTasks">
  <div *ngFor="let value of todo.myMap.values()">
    {{value.attribute}}
  </div>
</div>

edited Oct 10 '19 at 12:26

answered Oct 10 '19 at 11:29

JuNe

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I tried it.doesn't work because in array is object and in object are objects. – student_it Oct 10 '19 at 11:42
Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays. – student_it Oct 10 '19 at 12:02
You mean you have a map of objects in your object? – JuNe Oct 10 '19 at 12:03
Yes, I have a map of objects in your object. – student_it Oct 10 '19 at 12:06
I have edited my answer. Have a look at it. Here is a tutorial for your problem I think: https://howtodoinjava.com/typescript/for-of-loop/ – JuNe Oct 10 '19 at 12:26

Iterating over an object from the database

2 Answers2