EFPagination.AspNetCore 2.0.0

Entity Framework Pagination (EFPagination)

Keyset pagination for Entity Framework Core. Also known as seek or cursor pagination.

Keyset pagination delivers stable query performance regardless of page depth, unlike offset pagination (Skip/Take) which degrades linearly as you skip more rows.

Installation

dotnet add package EFPagination

For ASP.NET Core integration (optional):

dotnet add package EFPagination.AspNetCore

Requires .NET 10 and EF Core 10.

Quick Start

using EFPagination;

// Build once and store as a static readonly field.
static readonly PaginationQueryDefinition<User> Definition =
    PaginationQuery.Build<User>(b => b.Descending(x => x.Created).Ascending(x => x.Id));

// First page.
var page = await dbContext.Users
    .Keyset(Definition)
    .TakeAsync(20);

// Next page -- pass the cursor from the previous response.
var nextPage = await dbContext.Users
    .Keyset(Definition)
    .After(page.NextCursor!)
    .TakeAsync(20);

// Previous page.
var prevPage = await dbContext.Users
    .Keyset(Definition)
    .Before(nextPage.PreviousCursor!)
    .TakeAsync(20);

What's Included

• Fluent keyset pagination via .Keyset(definition).After(cursor).TakeAsync(20)
• CursorPage<T> with opaque NextCursor/PreviousCursor tokens
• IAsyncEnumerable streaming via .Keyset(definition).StreamAsync(100)
• Prebuilt definitions with cached expression tree templates for zero per-request overhead
• SortField.Create<T> one-line sort field factory
• PaginationSortRegistry<T> for request-driven dynamic sorting
• Opaque cursor encoding/decoding with schema fingerprinting and optional HMAC signing
• PaginationQuery.Build<T>(string, ...) for runtime sort definitions
• Low-level Paginate() API for custom IQueryable composition
• ASP.NET Core integration: PaginationRequest, PaginatedResponse<T>, FromRequest, ToPaginatedResponse
• Roslyn analyzers: nullable columns (KP0001), non-unique tiebreakers (KP0002), ad-hoc builders in hot paths (KP0003), missing order correction (KP0004)

API

Keyset (Fluent API)

The primary API surface. Chain .Keyset() on any IQueryable<T>:

// First page
var page = await db.Users
    .Keyset(definition)
    .TakeAsync(20);

// Forward from cursor
var page = await db.Users
    .Keyset(definition)
    .After(cursor)
    .TakeAsync(20);

// Backward from cursor
var page = await db.Users
    .Keyset(definition)
    .Before(cursor)
    .TakeAsync(20);

// With total count
var page = await db.Users
    .Keyset(definition)
    .After(cursor)
    .IncludeCount()
    .TakeAsync(20);

// With max page size clamp (defaults to 500)
var page = await db.Users
    .Keyset(definition)
    .After(cursor)
    .MaxPageSize(100)
    .TakeAsync(requestedPageSize);

// With entity reference instead of cursor
var page = await db.Users
    .Keyset(definition)
    .AfterEntity(lastUser)
    .TakeAsync(20);

// Stream all pages
await foreach (var batch in db.Users.Keyset(definition).StreamAsync(100))
{
    // process batch
}

TakeAsync returns CursorPage<T>:

PaginationQueryDefinition<T>

A prebuilt, reusable pagination definition. Build once, reuse across requests:

static readonly PaginationQueryDefinition<User> Definition =
    PaginationQuery.Build<User>(b => b.Descending(x => x.Created).Ascending(x => x.Id));

PaginationQuery

Factory for building reusable definitions:

// From a builder action (recommended):
PaginationQueryDefinition<T> Build<T>(Action<PaginationBuilder<T>> builderAction)

// From a property name string (for runtime sort fields):
PaginationQueryDefinition<T> Build<T>(
    string propertyName,
    bool descending,
    string? tiebreaker = "Id",
    bool tiebreakerDescending = false)

PaginationBuilder<T>

Fluent builder for defining pagination columns, used inside PaginationQuery.Build<T>():

Nested properties are supported: b.Ascending(x => x.Details.Created).

PaginationSortRegistry<T> / SortField

Map request sort names to prebuilt definitions:

var sorts = new PaginationSortRegistry<User>(
    defaultDefinition: PaginationQuery.Build<User>(b => b.Descending(x => x.Created).Ascending(x => x.Id)),
    SortField.Create<User>("created", "Created"),
    SortField.Create<User>("name", "Name"));

var definition = sorts.Resolve(sortBy, sortDir);

SortField.Create<T> builds both ascending and descending definitions from a property name:

SortField<T> Create<T>(string name, string propertyName, string? tiebreaker = "Id")

Paginate (Low-Level API)

For consumers who need raw IQueryable composition (e.g., .Include(), .Select(), custom materialization):

var context = db.Users.Paginate(definition, direction, reference);

var users = await context.Query
    .Include(x => x.Details)
    .Take(20)
    .ToListAsync();

PaginationContext<T> exposes:

PaginationCursor

Encode and decode opaque cursor tokens:

string Encode(ReadOnlySpan<ColumnValue> values, PaginationCursorOptions? options = null);

bool TryDecode<T>(ReadOnlySpan<char> encoded, PaginationQueryDefinition<T> definition, out PaginationValues<T> values, out int written)

PaginationCursorOptions supports SchemaFingerprint (stale cursor rejection) and SigningKey (HMAC verification).

PaginationDirection

enum PaginationDirection { Forward, Backward }

IncompatibleReferenceException

Thrown when a reference object is missing a property required by the pagination definition.

EFPagination.AspNetCore

PaginationRequest

Binds cursor-based pagination parameters from the query string:

public readonly record struct PaginationRequest(
    string? After = null,
    string? Before = null,
    int PageSize = 25,
    string? SortBy = null,
    string? SortDir = null);

Fluent Integration

Use FromRequest to apply cursors from a request, or Keyset(registry, request) for dynamic sorting:

// Fixed definition
var page = await db.Users
    .Keyset(definition)
    .FromRequest(request)
    .MaxPageSize(100)
    .TakeAsync(request.PageSize);

return page.ToPaginatedResponse(u => new UserDto(u.Id, u.Name));

// Dynamic sorting via registry
var page = await db.Users
    .Keyset(sortRegistry, request)
    .MaxPageSize(100)
    .TakeAsync(request.PageSize);

return page.ToPaginatedResponse(u => new UserDto(u.Id, u.Name));

PaginatedResponse<T>

JSON-serializable response envelope:

public sealed record PaginatedResponse<T>(
    IReadOnlyList<T> Items,
    string? NextCursor,
    string? PreviousCursor,
    int? TotalCount);

ToPaginatedResponse

Convert a CursorPage<T> to a PaginatedResponse<T>:

PaginatedResponse<T> ToPaginatedResponse<T>(this CursorPage<T> page);
PaginatedResponse<TOut> ToPaginatedResponse<T, TOut>(this CursorPage<T> page, Func<T, TOut> selector)

Documentation

Samples

The samples directory contains a Razor Pages demo with four pagination variations and Minimal API endpoints showcasing cursor-based pagination with sort registries.

License

MIT