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Tree Grid

Source: TypeScript / Java
The Tree Grid component displays hierarchical tabular data grouped in expandable nodes.

Tree Grid is a component for displaying hierarchical tabular data grouped into expandable nodes.

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async dataProvider(
  params: GridDataProviderParams<Person>,
  callback: GridDataProviderCallback<Person>
) {
  // The requested page and the full length of the corresponding
  // hierarchy level is requested from the data service
  const { people, hierarchyLevelSize } = await getPeople({
    count: params.pageSize,
    startIndex: params.page * params.pageSize,
    managerId: params.parentItem ? params.parentItem.id : null,
  });

  callback(people, hierarchyLevelSize);
}

protected override render() {
  return html`
    <vaadin-grid .itemHasChildrenPath="${'manager'}" .dataProvider="${this.dataProvider}">
      <vaadin-grid-tree-column path="firstName"></vaadin-grid-tree-column>
      <vaadin-grid-column path="lastName"></vaadin-grid-column>
      <vaadin-grid-column path="email"></vaadin-grid-column>
    </vaadin-grid>
  `;
}
Note
 Tree Grid is an extension of the Grid component. Therefore, all of Grid’s features are available in Tree Grid. However, Tree Grid isn’t meant to be used as a navigation menu.

Tree Column

The tree column contains the toggles for expanding and collapsing nodes. Nodes are opened and closed by clicking a tree column’s cell. They can also be toggled programmatically.

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@state()
private expandedItems: unknown[] = [];

protected override render() {
  return html`
    <vaadin-horizontal-layout
      style="align-items: center; height: var(--lumo-size-xl);"
      theme="spacing"
    >
      <h3 style="flex-grow: 1; margin: 0;">Employee</h3>
      <vaadin-button @click="${this.expandAll}">Expand All</vaadin-button>
      <vaadin-button @click="${this.collapseAll}">Collapse All</vaadin-button>
    </vaadin-horizontal-layout>

    <vaadin-grid
      .dataProvider="${this.dataProvider}"
      .itemIdPath="${'id'}"
      .itemHasChildrenPath="${'manager'}"
      .expandedItems="${this.expandedItems}"
    >
      <vaadin-grid-tree-column path="firstName"></vaadin-grid-tree-column>
      <vaadin-grid-column path="lastName"></vaadin-grid-column>
      <vaadin-grid-column path="email"></vaadin-grid-column>
    </vaadin-grid>
  `;
}

private expandAll() {
  this.expandedItems = [...this.managers];
}

private collapseAll() {
  this.expandedItems = [];
}

Rich Content

Like Grid, Tree Grid supports rich content.

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private employeeRenderer: GridColumnBodyLitRenderer<Person> = (person, model) => html`
  <vaadin-grid-tree-toggle
    .leaf="${!person.manager}"
    .level="${model.level ?? 0}"
    @expanded-changed="${(e: GridTreeToggleExpandedChangedEvent) => {
      if (e.detail.value) {
        this.expandedItems = [...this.expandedItems, person];
      } else {
        this.expandedItems = this.expandedItems.filter((p) => p.id !== person.id);
      }
    }}"
    .expanded="${!!model.expanded}"
  >
    <vaadin-horizontal-layout style="align-items: center;" theme="spacing">
      <vaadin-avatar
        img="${person.pictureUrl}"
        name="${`${person.firstName} ${person.lastName}`}"
      ></vaadin-avatar>
      <vaadin-vertical-layout style="line-height: var(--lumo-line-height-m);">
        <span>${person.firstName} ${person.lastName}</span>
        <span
          style="font-size: var(--lumo-font-size-s); color: var(--lumo-secondary-text-color);"
        >
          ${person.profession}
        </span>
      </vaadin-vertical-layout>
    </vaadin-horizontal-layout>
  </vaadin-grid-tree-toggle>
`;

private contactRenderer: GridColumnBodyLitRenderer<Person> = (person) => html`
  <vaadin-vertical-layout
    style="font-size: var(--lumo-font-size-s); line-height: var(--lumo-line-height-m);"
  >
    <a href="mailto:${person.email}" style="align-items: center; display: flex;">
      <vaadin-icon
        icon="vaadin:envelope"
        style="height: var(--lumo-icon-size-s); margin-inline-end: var(--lumo-space-s); width: var(--lumo-icon-size-s);"
      ></vaadin-icon>
      <span>${person.email}</span>
    </a>
    <a href="tel:${person.address.phone}" style="align-items: center; display: flex;">
      <vaadin-icon
        icon="vaadin:phone"
        style="height: var(--lumo-icon-size-s); margin-inline-end: var(--lumo-space-s); width: var(--lumo-icon-size-s);"
      ></vaadin-icon>
      <span>${person.address.phone}</span>
    </a>
  </vaadin-vertical-layout>
`;

protected override render() {
  return html`
    <vaadin-grid .dataProvider="${this.dataProvider}" .expandedItems="${this.expandedItems}">
      <vaadin-grid-column
        auto-width
        header="Employee"
        ${columnBodyRenderer(this.employeeRenderer, [])}
      ></vaadin-grid-column>
      <vaadin-grid-column
        auto-width
        header="Contact"
        ${columnBodyRenderer(this.contactRenderer, [])}
      ></vaadin-grid-column>
    </vaadin-grid>
  `;
}

Programmatic Scrolling

Grid supports programmatic navigation to a specific row. This is particularly useful when dealing with large data sets. It saves users from having to scroll through potentially hundreds or thousands of rows.

To use this feature, you need to specify the index of the row you want to view. The scroll position of the grid will then be adjusted to bring that row into view.

With multiple levels of hierarchy, you need to specify the row index for each level, separately. For example, to scroll to the second child-row (index 1) of the third root-level row (index 2), you would provide the indexes 2, 1.

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this.grid.scrollToIndex(...this.indexesToScrollTo);
Component Usage Recommendation

Grid

Component for showing tabular data.

Grid Pro

Component for showing and editing tabular data.

CRUD

Component for creating, displaying, updating, and deleting tabular data.

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