demo D76
Orphans and cycles
Data that is not quite a tree. Nothing is dropped
orphans: 'Unassigned'
The configuration
import * as ng from '@angular/core';
import { Component } from '@angular/core';
import { bootstrapApplication } from '@angular/platform-browser';
import { createGrid } from '@toclocoinc/lattice-grid';
import '@toclocoinc/lattice-grid/css';
import createLatticeGrid from '@toclocoinc/lattice-grid/modules/angular';
const { LatticeGridComponent } = createLatticeGrid({ ng, createGrid });
// Rows naming a parent that is not in the extract go to the named bucket, and
// a cycle is cut and its rows shown at the root, with one console warning
// rather than one per row. No row is lost either way.
const tree = { parentKey: 'parentId', orphans: 'Unassigned', label: 'name', title: 'Circuit' };
const columns = [
{ field: 'source', title: 'Source', filter: { type: 'set' }, layout: { width: 160 } },
{ field: 'parentId', title: 'Names as parent', layout: { width: 220 } },
{ field: 'charge', title: 'Monthly charge', type: 'number', format: { style: 'currency', currency: 'GBP', decimals: 0 }, total: 'sum', layout: { width: 180 } },
];
const rows = [/* a parent reference with orphans and a cycle */];
@Component({
selector: 'app-root',
standalone: true,
imports: [LatticeGridComponent],
template: '<lattice-grid [config]="grid" style="display:block;height:540px"></lattice-grid>',
})
export class AppComponent {
grid = {
rowKey: 'id',
selection: 'multiple',
grandTotalRow: 'bottom',
tree: tree,
toolPanel: { side: 'left', panels: ['columns', 'filters', 'views', 'quick'],
actions: ['undo', 'redo', 'export', 'restore', 'maximise'], exportName: 'lattice-demo' },
columns: columns,
rows: rows,
};
}
bootstrapApplication(AppComponent);Handling broken hierarchies: missing parents and cyclic references
Real hierarchy data is rarely a clean tree. A parent ID can point at a row that was filtered out upstream, deleted from the source system, or never existed in the first place, and occasionally a chain of parent references loops back on itself. A developer reaches for this when building tree data from a flat table sourced from a database join or a CSV export, where referential integrity was never guaranteed. Lattice Grid handles both cases without dropping rows: set orphans: 'Unassigned' and any row whose declared parent cannot be found is regrouped under a synthetic bucket with that label, rather than being silently excluded from the grid or, worse, from a total. Cycles are detected during tree construction, so a row that would otherwise reference its own descendant as a parent is broken out into the same fallback grouping instead of causing infinite recursion. Because this is a JavaScript data grid built for incremental updates, the orphan bucket recalculates only for the rows affected by a change, not the whole tree. This matters for accessibility as well as correctness: a screen reader announcing group counts should never encounter a total that silently excludes rows the user cannot otherwise account for.
What happens to rows with a missing or invalid parent ID in a tree grid?
Lattice Grid groups them under a fallback node rather than discarding them. Setting orphans: 'Unassigned' on the tree configuration names that node, so every row whose parent reference cannot be resolved, including rows caught in a circular reference, still appears in the grid, still counts toward totals, and remains visible to filtering and search.