Boot Strap Accordian Not collapsing - html

Question

Hi y'all I'm trying to replicate a collapsing accordian example I found on https://getbootstrap.com/docs/4.1/components/collapse/ but for some reason they are not collapsing. In fact they start in the uncollapsed position which I think is strange because in the exmaple they start collapsed and then on the button click they collapse open. Anyways here is my code, I hope someone out there can help because I can't figure this out.
FINAL UPDATE: for any googlers that stumble upon this Here is the code that worked for me. Notice that the data-target => attr.data-target is the only way to use text binding with the data-target
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>
<div class="accordion" id="accordionExample">
<div class="card" *ngFor="let grocery of groceryList;index as index">
<div class="card-header" id="grocery1{{index}}">
<h5 class="mb-0">
<button class="btn btn-link" type="button" data-toggle="collapse" attr.data-target="#grocery2{{index}}" aria-expanded="true" aria-controls="grocery2{{index}}">
{{grocery.recipeName}}
</button>
</h5>
</div>
<div id="grocery2{{index}}" class="collapse show" aria-labelledby="grocery1{{index}}" data-parent="#accordionExample">
<div class="card-body">
<ul class="list-group" id="filterList">
<li class="list-group-item">
<span class="glyphicon glyphicon-chevron-down"></span>
<ul id="subgroup" class="list-group">
<li class="list-group-item" *ngFor="let ingredient of grocery.ingredients">{{ingredient}}</li>
</ul>
</li>
</ul>
</div>
</div>
</div>
</div>

Answer 1

So following you will find the list of problem you had:
ID are similar from header and child
Missing double quote
Simulation did not worked here because of the "." in the id that are breaking the ID
PS: Based on your code your code, the problem is that actualy you have a conflic between Bootstrap and another tool, because it does not show the arial-controls.
Please find a snippet demo working below:
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>
<div class="accordion" id="accordionExample">
<div class="card" *ngFor="let grocery of groceryList">
<div class="card-header" id="grocery1">
<h5 class="mb-0">
<button class="btn btn-link" type="button" data-toggle="collapse" data-target="#grocery2" aria-expanded="true" aria-controls="grocery2">
{{grocery.recipeName}}
</button>
</h5>
</div>
<div id="grocery2" class="collapse show" aria-labelledby="grocery1" data-parent="#accordionExample">
<div class="card-body">
<ul class="list-group" id="filterList">
<li class="list-group-item">
<span class="glyphicon glyphicon-chevron-down"></span>
<ul id="subgroup" class="list-group">
<li class="list-group-item" *ngFor="let ingredient of grocery.ingredients">{{ingredient}}</li>
</ul>
</li>
</ul>
</div>
</div>
</div>
</div>
It seems that Angular and Bootstrap accordion/collapse are no so friendly based on the different subject on stack overflow:
Bootstrap collapse menu doesn't work with angular
Angular 4: Bootstrap's collapse does not work using data-target attribute
angular-bootstrap accordion won't open