Ability to override getItemMetadata for non-group rows in DataView

[vlsi]

DataView always returns null for non-group rows in getItemMetadata:

SlickGrid/slick.dataview.js

Lines 455 to 471 in 14bb1a8

	function getItemMetadata(i) {
	var item = rows[i];
	if (item === undefined) {
	return null;
	}
	// overrides for grouping rows
	if (item.__group) {
	return options.groupItemMetadataProvider.getGroupRowMetadata(item);
	}
	// overrides for totals rows
	if (item.__groupTotals) {
	return options.groupItemMetadataProvider.getTotalsRowMetadata(item);
	}
	return null;

Use case: "add css class to the grid row when item has certain property".
metadata.cssClasses seems to be the way to add row css classes, however DataView does not allow to use that:

SlickGrid/slick.grid.js

Lines 1680 to 1686 in 14bb1a8

	var metadata = data.getItemMetadata && data.getItemMetadata(row);
	if (metadata && metadata.cssClasses) {
	rowCss += " " + metadata.cssClasses;
	}
	stringArray.push("<div class='ui-widget-content " + rowCss + "' style='top:" + getRowTop(row) + "px'>");

[vlsi]

PS. The sad thing with getItemMetadata is it is used in multiple places, and there's no way to provide the metadata lazily.
In other words, metadata.cssClasses and metadata.columns are used in different grid methods, however getItemMetadata has to return all of the metadata values every time.

[6pac]

Perhaps this lack of row level DataView metadata needs addressing. There have been complaints about how often metadata is fetched, too. I'll be too busy for even minor re-architecting until september. Happy to accept sensible PRs in the meantime.

[6pac]

I seem to recall that I added a way to define row css in my personal repo, then added it across to the main repo. I usually document these things by adding an example, rather than by adding to the wiki (bad, I know!).
Have you checked out the extended formatter behaviour in http://6pac.github.io/SlickGrid/examples/example2-formatters.html

[rohanc]

The example linked above seems to demonstrate adding CSS to cells, but not to whole rows.

There are various recipes on stackoverflow for adding CSS to whole rows, as long as you are using DataView. These involve overriding the getItemMetadata method. e.g.

https://stackoverflow.com/questions/8930167/how-do-i-add-a-css-class-to-particular-rows-in-slickgrid

function row_metadata(old_metadata_provider) {
  return function(row) {
    var item = this.getItem(row),
        ret = old_metadata_provider(row);

    if (item && item._dirty) {
      ret = ret || {};
      ret.cssClasses = (ret.cssClasses || '') + ' dirty';
    }

    return ret;
  };
}

dataView.getItemMetadata = row_metadata(dataView.getItemMetadata);

Since I upgraded from v2 to v5, I found I need to provide this context when calling old_metadata_provider:

ret = old_metadata_provider.call(this,row) || {}

Then it works again. I'm unsure whether const item=this.rows[row] or this.getItem(row) (as in the original from slick.dataview.ts) is more appropriate. Both seem to work.

[ghiscoding]

Since I upgraded from v2 to v5, I found I need to provide this context when calling old_metadata_provider:

ret = old_metadata_provider.call(this,row) || {}

Then it works again. I'm unsure whether const item=this.rows[row] or this.getItem(row) (as in the original from slick.dataview.ts) is more appropriate. Both seem to work.

You need to provide this because we migrated to TypeScript and ES Modules, we no longer use any var which previously had global access scope but since we now use TypeScript Classes, we need to provide the this scope in some cases, I did mention a similar migration step to be done for the DraggableGrouping here but yeah it's possible that there are other special cases like the one you just encountered.