Sometimes when scrolling through table rows, I receive warning: Failed prop type: The prop `index` is marked as required in `FixedDataTableRowImpl`, but its value is `null`.

In my case I receive warning when there are more rows to fit in the screen and I scroll to the bottom then start to scroll back to the top. In most times this is enough to get warning but not always.

index.js:1 Warning: Failed prop type: The prop `index` is marked as required in `FixedDataTableRowImpl`, but its value is `null`.
    at FixedDataTableRowImpl (http://localhost:3011/merch/static/js/vendors~main.chunk.js:46437:5)
    at FixedDataTableRow (http://localhost:3011/merch/static/js/vendors~main.chunk.js:46917:5)
    at div
    at FixedDataTableBufferedRows (http://localhost:3011/merch/static/js/vendors~main.chunk.js:44209:5)
    at div
    at div
    at FixedDataTable (http://localhost:3011/merch/static/js/vendors~main.chunk.js:42937:5)
    at ScrollContainer (http://localhost:3011/merch/static/js/vendors~main.chunk.js:47930:5)
    at FixedDataTableContainer (http://localhost:3011/merch/static/js/vendors~main.chunk.js:46105:5)
    at Table (http://localhost:3011/merch/static/js/main.chunk.js:9559:3)
    at div
    at DynamicWidth (http://localhost:3011/merch/static/js/main.chunk.js:9774:3)
    at TableContainer (http://localhost:3011/merch/static/js/main.chunk.js:10142:3)
    at Ue (http://localhost:3011/merch/static/js/main.chunk.js:11531:9)
    at Ge (http://localhost:3011/merch/static/js/main.chunk.js:11605:13)
    at Route (http://localhost:3011/merch/static/js/vendors~main.chunk.js:168474:29)
    at Switch (http://localhost:3011/merch/static/js/vendors~main.chunk.js:168676:29)
    at div
    at push.../../ws-core/ws-core-ui/dist/index.js.exports.TaskRoutes (http://localhost:3011/merch/static/js/main.chunk.js:11904:13)
    at TaskRoutes (http://localhost:3011/merch/static/js/main.chunk.js:101258:3)
    at Route (http://localhost:3011/merch/static/js/vendors~main.chunk.js:168474:29)
    at Switch (http://localhost:3011/merch/static/js/vendors~main.chunk.js:168676:29)
    at ErrorBoundary (http://localhost:3011/merch/static/js/main.chunk.js:95757:5)
    at Oe (http://localhost:3011/merch/static/js/main.chunk.js:11312:13)
    at Re (http://localhost:3011/merch/static/js/main.chunk.js:11369:13)
    at push.../../ws-core/ws-core-ui/dist/index.js.exports.CoreContainer (http://localhost:3011/merch/static/js/main.chunk.js:11878:13)
    at AdminLayout (http://localhost:3011/merch/static/js/main.chunk.js:94648:1)
    at AdminRouter (http://localhost:3011/merch/static/js/main.chunk.js:95092:1)
    at Route (http://localhost:3011/merch/static/js/vendors~main.chunk.js:168474:29)
    at ProtectedRouteBase (http://localhost:3011/merch/static/js/main.chunk.js:7125:1)
    at ProtectedRoute (http://localhost:3011/merch/static/js/main.chunk.js:66514:5)
    at WithAppContextFunctions (http://localhost:3011/merch/static/js/main.chunk.js:69329:7)
    at Switch (http://localhost:3011/merch/static/js/vendors~main.chunk.js:168676:29)
    at http://localhost:3011/merch/static/js/vendors~main.chunk.js:117447:23
    at AdminRoot
    at Router (http://localhost:3011/merch/static/js/vendors~main.chunk.js:168105:30)
    at Provider (http://localhost:3011/merch/static/js/vendors~main.chunk.js:165342:20)
    at AppComponent
    at ContextProvider (http://localhost:3011/merch/static/js/vendors~main.chunk.js:54205:25)

If, I look at FixedDataTableBufferedRows.js code, I see that index can be null:

fixed-data-table-2/src/FixedDataTableBufferedRows.js

Lines 130 to 138 in 9aa115c

    
           // if the row doesn't exist in the buffer set, then take the previous one 
        
           if (rowIndex === undefined) { 
        
             rowIndex = 
        
               this._staticRowArray[i] && this._staticRowArray[i].props.index; 
        
             if (rowIndex === undefined) { 
        
               this._staticRowArray[i] = null; 
        
               continue; 
        
             } 
        
           }

Debugging also approves this situation:

The biggest issue is not a warning in FixedDataTableRow.js but that table cell with rowIndex=null is rendered:

fixed-data-table-2/src/FixedDataTableCell.js

Line 310 in ad60599

content = props.cell(cellProps);

When documentation in https://github.com/schrodinger/fixed-data-table-2 says:
The cell components in a column will receive the current array index of your data as a prop (this.props.rowIndex). Use this to access the correct value for each cell.

const rows = [0,1,2];
    
<Column
  header={<Cell>Column 1</Cell>}
  cell={({rowIndex, ...props}) => (
    <Cell {...props}>
    {rows[rowIndex]}
    </Cell>
  )}
  width={2000}
/>

So, in my case I get rows[rowIndex]=undefined...

I can fix this for my case, but I guess that in such case cell renderer should not be called.

Hey, thanks for the detailed analysis.
As you mentioned, I suspect we just need a broader falsey check on rowIndex and force the row instance to not be rendered in this case.

I'll be happy to consider a PR for this. If not, I can also tackle this myself in a few days.

Meanwhile, could you also mention the exact version of FDT that's used here?

Hi @pradeepnschrodinger, thank you for quick response. Unfortunately, I don't have more time to make PR. I am using latest FDT version 1.2.9.

Hi @pradeepnschrodinger, you were correct. There is a flaw in logic when assigning rowIndex. In case when _staticRowArray[i] already assigned to null, we should keep it as undefined so it can skip rendering that row.

This should now be resolved with v1.2.10 through #645.

Thanks @pauliusg and @tkirda!

	// if the row doesn't exist in the buffer set, then take the previous one
	if (rowIndex === undefined) {
	rowIndex =
	this._staticRowArray[i] && this._staticRowArray[i].props.index;
	if (rowIndex === undefined) {
	this._staticRowArray[i] = null;
	continue;
	}
	}