Favorite column modifies data source but should not interfere

[tscherfler]

Bug Report

Expected Behavior

Favorite column should not modify my data source.

Current Behavior

Modifies data by reference.

barista/components/table/src/simple-columns/favorite-column.ts

Line 64 in 5ffbd2c

data[this.name] = !data[this.name];

Possible Solution

Hold favorite state in component itself.

Steps to Reproduce

When data in datasource is immutable this breaks.

Context (Environment)

Used Versions:

• @dynatrace/barista-components: 5.0.1

[tomheller]

Additionally the example binding is wrongfully called change here:

barista/libs/examples/src/table/table-favorite-column-example/table-favorite-column-example.html

Line 5 in 5ffbd2c

(change)="doSomething()"

barista/libs/examples/src/table/table-favorite-column-no-header-example/table-favorite-column-no-header-example.html

Line 5 in 5ffbd2c

(change)="doSomething($event)"

when the actual output is called favoriteToggled:

barista/components/table/src/simple-columns/favorite-column.ts

Line 43 in 5ffbd2c

@Output() readonly favoriteToggled = new EventEmitter<T>();

[tomheller]

After a short investigation, this is what I have found:
If the data in the datasource is immutable (the object has been frozen somewhere in the process) we cannot mutate the data on the original object. We as the component providers should not modify the data within that source.

Here is what I would propose as a solution:
In the favorite-colum.ts file

barista/components/table/src/simple-columns/favorite-column.ts

Line 64 in 53241e1

data[this.name] = !data[this.name];

I would remove the modification of the original data.

The modification of the original data is best handled by the consumer of the component library, as we cannot know if the data is mutable or not. They can react to the event and handle the modifications of their data accordingly.

@yngrdyn I would really appreciate your input on this one.

[yngrdyn]

Hello @tomheller, I'll take a look in this

[tomheller]

Thank you @yngrdyn, you are brilliant 🎉 🤘 .