Why is it that the changes I make in the parent component do not reflect in my Angular component?

As I embarked on creating a custom select component, I began with the input below:

@Input() options: SelectOption<UserRole>[] = [];

The parent component (user editor) utilizes this select component and provides the options as shown below:

roleOptions: SelectOption<UserRole>[] = [
   { value: 'USER', label: 'User', selected: false },
   { value: 'ADMIN', label: 'Admin', selected: false },
];

When the parent component loads the current user along with its user role, it sets the role in the constructor as follows:

// ... get user here ...
this.roleOptions.filter((o) => o.value === user.role).map((o) => (o.selected = true));

Within the select component, my aim is to adjust the displayed value based on the user's assigned role during ngOnInit (or any relevant lifecycle hook). However, I encountered an issue where the 'selected' value always remains false when filtered for it:

this.displayedValue = this.options.filter((o) => o.selected)[0].label;

While I can observe the changes in all options when printing them, the selected role is not found when attempting to filter for it. I experimented with ngOnChanges but faced the same outcome. Can someone shed light on why this is happening? How can I successfully display the assigned role?

Answer №1

Ensure the complete object is returned in the map operation!

Previous code snippet:

this.filterOptions.filter((item) => item.id === selectedId).map((item) => (item.checked = true));

Updated code snippet:

this.filterOptions.filter((item) => item.id === selectedId).map((item) => {item.checked = true; return item;});

For better understanding, please provide a stackblitz showcasing the problem for easier troubleshooting!

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