Pagination

ng-qubee covers both sides of pagination: building the request URI (with setPage / setLimit and the navigation helpers below) and parsing the paginated response into a typed PaginatedCollection<T>.

Navigation helpers

Fluent methods that mutate state.page. All return this for chaining.

qb.nextPage();        // state.page + 1, capped at lastPage if known
qb.previousPage();    // state.page - 1, floored at 1
qb.firstPage();       // page = 1
qb.lastPage();        // page = state.lastPage; throws if not synced yet
qb.goToPage(n);       // validates and sets, rejects n > lastPage when known

The lastPage value is populated automatically by PaginationService.paginate() — see auto-sync below.

State accessors

qb.currentPage();     // state.page (always safe)
qb.totalPages();      // state.lastPage; throws if paginate() hasn't run yet

Predicates (template-safe)

Conservative defaults when bounds are unknown — usable directly in [disabled] bindings without a guard:

qb.isFirstPage();        // page === 1
qb.isLastPage();         // false until lastPage is known, then page === lastPage
qb.hasNextPage();        // true until lastPage is known, then page < lastPage
qb.hasPreviousPage();    // page > 1

Template wiring:

<button [disabled]="qb.isFirstPage()" (click)="qb.previousPage()">Prev</button>
<span>Page {{ qb.currentPage() }} of {{ qb.totalPages() }}</span>
<button [disabled]="qb.isLastPage()" (click)="qb.nextPage()">Next</button>

Parsing a response

Every driver hands you an Observable<HttpResponse> from your HTTP client. Pass the body (and headers, when relevant) to PaginationService.paginate():

this._http.get(uri).subscribe(body => {
  const collection = this._pagination.paginate(body);
  // collection.data, collection.page, collection.lastPage, …
});

For the PostgREST driver, also pass headers — the total count lives in Content-Range:

this._http.get(uri, { observe: 'response', headers: { 'Prefer': 'count=exact' } })
  .subscribe(response => {
    const collection = this._pagination.paginate(response.body, response.headers);
  });

The second argument accepts Angular's HttpHeaders, the native Headers class, or a plain Record<string, string>.

PaginatedCollection<T>

The parsed shape is uniform across all drivers:

class PaginatedCollection<T> {
  readonly data: T[];
  readonly page: number;
  readonly from?: number;
  readonly to?: number;
  readonly total?: number;
  readonly perPage?: number;
  readonly prevPageUrl?: string;
  readonly nextPageUrl?: string;
  readonly lastPage?: number;
  readonly firstPageUrl?: string;
  readonly lastPageUrl?: string;
}

Optional fields are undefined when the driver/server didn't provide them.

Auto-sync

When paginate() returns a PaginatedCollection with a positive integer lastPage, the library writes it back into NestService automatically:

• state.page ← collection.page
• state.lastPage ← collection.lastPage
• state.isLastPageKnown ← true

This means the navigation helpers above (nextPage, lastPage, predicates) start working immediately after the first paginate() call — no consumer bookkeeping required.

Server-emitted 0 (empty collection) and absent lastPage fields leave isLastPageKnown as false so predicates fall back to their conservative defaults.

Errors

Error	Thrown by	When
PaginationNotSyncedError	lastPage(), totalPages()	Called before any paginate() call has synced lastPage
InvalidPageNumberError	setPage(n), goToPage(n)	n is not a positive integer, or exceeds state.lastPage when known
InvalidLimitError	setLimit(n)	n is not accepted by the active driver — see per-driver pages

RANGE-header pagination (PostgREST only)

See PostgREST → RANGE-header pagination for opt-in details.

paginationHeaders() returns the headers to apply ({ 'Range-Unit': 'items', 'Range': '0-9' }) or null for all other drivers — safe to spread into a headers map unconditionally.