Cannot filter by date equals to

[MadalenaPavao]

I want to filter a date column, and I want it to display the dates EQUAL to the one chosen by the user. But specifying "equals" in the filterFn doesn't work. In fact, the example provided by Material React Table, using "lessThanOrEqualTo" only shows values "lessThan" the selected date, never "equal".
Here's my column definition:

{
        header: 'Date',
        accessorFn: (row) => new Date(row.date), //convert to Date for sorting and filtering
        id: 'start_date',
        filterFn: 'lessThanOrEqualTo',
        sortingFn: 'datetime',
        Cell: ({ cell }) => (
          <Typography>
            {new Date(cell.getValue())}
          </Typography>
        ),
        Filter: ({ column }) => (
          <LocalizationProvider dateAdapter={AdapterDayjs} >
            <DatePicker
              onChange={(newValue) => {
                column.setFilterValue(newValue);
              }}
              disableFuture
              slotProps={{
                textField: {
                  helperText: 'Filter Mode: Less Than',
                  sx: { minWidth: '120px' },
                  variant: 'standard',
                },
              }}
              value={column.getFilterValue()}
            />
          </LocalizationProvider>
        ),
      },

How should I do to filter by the exact date?

[jorgemoralespou]

I had similar problem, and looking at the code, the equals filter function does not filter dates, so I created a similar function that filters by date, and used that in the filterFn:

filterFn: <TData extends Record<string, any> = {}>(
  row: Row<TData>,
  id: string,
  filterValue: Date,
) => isSameDay(row.getValue<Date>(id), filterValue);