RenderComponent - ViewCell Interface Too Restrictive

[wabudd1]

I'm not sure if there's a specific reason for it to be this way, but the ViewCell interface only allows string | number, but I have a complex object in my data. Ultimately, I'd like to be able to have a RenderComponent that is able to do this.renderedValue = this.value.fullName. It seems as easy as changing the ViewCell.value property to any. Is there a reason not to make this change?

[uap-universe]

One of the goals is to remove any where possible to become more type-safe.

That said, the custom renderer stuff is way more fucked up as you might think. Because the truth is, that the renderer receives the object returned by the valuePrepareFunction no matter what the type is.

This is because typescript is not type-safe. You can actually assign arbitrary objects to value: string|number and they do not need to be string or number. You just need to make it so the compiler does not see it.

So you can - without regrets - just implement your renderer like this

// assume your row data looks like this
export class MyComplexObject {
   attr: MyComplexAttribute;
   // ...
}

export class MyComplexAttribute {
   fullName: string;
   // ...
}

export class MyRenderComponent implements OnInit, ViewCell {

    // @ts-ignore
    @Input() value: MyComplexAttribute | string;
    @Input() rowData!: MyComplexObject;

    data!: MyComplexAttribute;

    ngOnInit(): void {
        this.data = this.value as MyComplexAttribute;
        this.value = this.data.fullName; // for example - but you don't need this,
                                                          // you can directly use the stuff in the HTML template

The default valuePrepareFunction returns the string representation of your attribute. So you need a custom one, just returning your attribute.

settings = {
  // ...
  columns: {
    // ...
    attr: {
      // ...
      valuePrepareFunction: (value, row, cell) => value
   }
  }
}

The same does not only work with value. You can also return row or cell from the valuePrepareFunction and then this is accessible in your renderer.

Of course it would be nice to have a decent type for ViewCell.value and I can understand that, given the circumstances, it might look like any is actually a correct choice (because the thing can obviously be literally anything).

Currently the correct type would be T | Property | Cell<T, Property> | Row<T> where T is the type of the object (MyComplexObject here) and Property is the type of the property rendered in this column (MyComplexAttribute here).

Changing that in a reasonable way is not so easy. I keep this ticket open as a reminder and tag it with enhancement.

[wabudd1]

Excellent, thank you for taking the time to do that writeup. It makes a lot of sense.

[uap-universe]

Maybe somehow remotely related with #115 which suffers from similar type confusion problems. But maybe there the possibility for a non-breaking small step cleanup for v2.9.0.

[uap-universe]

Unfortunately, any sort of type change would be likely a (minor) breaking change for the users who already use the strict typing. Will reconsider this for the next major update 3.0.0.

[uap-universe]

Actually, we can get rid of the ViewCell interface entirely. There is no reason why the componentInit function shouldn't be sufficient to initialize the component with the cells value. This simplifies things a lot.