DKNet

Page and stream results

Part of DKNet.EfCore.Specifications. Use the ordered Quick Start specification for buffered streaming or a repository cursor page:

await foreach (var product in repo.ToPageEnumerable(new MinimumPrice(0)))
    Console.WriteLine(product.Name); // Coffee, then Tea
var next = await repo.ToKeysetPageAsync(new MinimumPrice(0), p => p.Id, cursor: 1, pageSize: 20);
Console.WriteLine(next.Single().Name); // Tea

Paging chooses offset materialization, buffered ordered enumeration, or a keyset cursor predicate before fetching rows; arbitrary keysets additionally check whether previous and next pages exist.

Surface	Ordering owner	Result
`repo.ToPagedListAsync(spec, pageNumber, pageSize)`	Specification	X.PagedList page; page number is 1-based.
`repo.ToPageEnumerable(spec)`	Specification, required	Async rows buffered in offset pages of 100.
`query.AfterKeyset` / `BeforeKeyset`	Caller	WHERE only; one or two ascending, comparable value-type keys.
`repo.ToKeysetPageAsync`	Specification, not enforced	List after a one-key or two-key ascending cursor.
`query.ToKeysetPageAsync(configureKeyset, ...)`	Configure delegate	`KeysetPage<TEntity>` with Items, HasPrevious, HasNext.

The queryable arbitrary-key overload uses MR.EntityFrameworkCore.KeysetPagination, supports mixed directions and forward/backward navigation, and accepts an optional reference object with matching key property names. It owns ordering as well as filtering. The two-key helper uses a lexicographic OR comparison with an additional leading bound on the first key; cursor values are captured as parameters.

⚙️ Configuration reference

Input	Type	Default	Effect
Buffered page size	Internal constant	`100`	Not exposed by repository enumeration helpers.
`pageSize` for keysets	`int`	Required	Must be positive; otherwise throws ArgumentOutOfRangeException.
Arbitrary-key `direction`	`KeysetPaginationDirection`	`Forward`	Cursor navigation direction.
Arbitrary-key `reference`	`object?`	`null`	Null selects the initial page.
Async cancellation	`CancellationToken`	Default	Observed by row materialization/enumeration; arbitrary-key existence checks do not accept it.

🧱 Where it fits

The query architecture shows the shared DbContext. Both entity and projected repository queries offer paged lists and buffered enumeration; keyset repository helpers return entities.

⚠️ Gotchas & limits

repo.ToPageEnumerable requires at least one declared order clause, otherwise NotSupportedException is thrown. Choose a unique tie-breaker for stable pages.
repo.ToKeysetPageAsync relies on the specification’s ordering and does not enforce it. Without an order clause it runs without ORDER BY, raises no error and returns rows in no fixed order.
Simple keyset keys must be comparable value types: the cursor filter uses >/<, so a string key throws.
Simple AfterKeyset/BeforeKeyset helpers do not sort. Match their ascending comparison with your ordering; use the configured arbitrary-key API for mixed directions.
Arbitrary-key paging makes a page query plus previous/next existence queries; only the page query observes the cancellation token.
Buffered enumeration is offset paging rather than a database cursor or a stable snapshot. Concurrent writes can shift page boundaries; tracking queries can retain entities across pages.
Do not pre-order the arbitrary-key overload and expect that ordering to win: pass all key columns to its configure delegate.

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