@kanunilabs/datagrid-react / SummaryDef
Interface: SummaryDef<TRow>
Type Parameters
TRow
TRow = GridRowData
Properties
calculate?
optionalcalculate?: (cells) =>number|null
The reducer for type: 'custom'. Receives every DATA cell of the column in
view order — group headers are already filtered out — and returns the
number to show, or null for "nothing to total".
A weighted average, a variance, a count of rows matching a predicate: all the things a fixed six-reducer set cannot express.
Parameters
cells
readonly SummaryCell<TRow>[]
Returns
number | null
columnId
columnId:
string
dependsOnOrder?
optionaldependsOnOrder?:boolean
Whether this custom reducer's answer can change when only the ORDER of
the rows changes (perf, 2026-08-14). Default true — the safe reading of
"receives cells in view order", and exactly the old behaviour.
Most customs are order-blind (a weighted average, a variance, a
conditional count); declaring false lets the grid reuse their result
when a sort merely rearranges the same rows. Measured on the 1M bench: an
order-blind custom re-ran on every sort at ~1.5 s a pass — for an answer
that could not have moved.
label?
optionallabel?:string
Label shown next to the value in the footer. Defaults to the type's name;
required in practice for custom, where "Custom" says nothing.
type
type:
SummaryType
valueFormatter?
optionalvalueFormatter?: (value) =>string
Display formatting for the footer; falls back to the column's formatter.
Parameters
value
number | null
Returns
string