README.md

persistence-flat-pagination-sorting-jdbc

Extends persistence-flat-pagination-jdbc with multi-field sorting — no Spring Data, pure SQL, clean architecture.

What it shows

• Multi-field sorting via SortRequest with domain field names — no SQL aliases in the application layer
• SQL alias mapping lives in the infrastructure adapter — FIELD_MAP translates domain names to SQL
• Dynamic ORDER BY built safely at the infrastructure boundary
• Offset-based pagination with LIMIT / OFFSET and COUNT(*)
• Using package-private classes as an encapsulation boundary inside the infrastructure layer

Stack

• Java 25
• Spring Boot
• Spring JDBC (JdbcClient)
• H2 (in-memory database)

Structure

application/
    OwnerReadRepository   ← port (interface)
    OwnerView             ← read model
    PageQuery             ← pagination + sort input
    PageResult<T>         ← pagination output
    SortRequest           ← sort field + direction with whitelist validation

infrastructure/
    JdbcOwnerReadRepository   ← JDBC implementation
    OwnerProjection           ← internal, never leaks out
    ViewMapper                ← projection → view

How it works

// no sorting — default ORDER BY o.id ASC
PageQuery.of(0, 10);

// single field
PageQuery.of(0, 10, List.of(SortRequest.asc("name")));

// multiple fields
PageQuery.of(0, 10, List.of(
    SortRequest.asc("name"),
    SortRequest.desc("id")
));

Why a whitelist

SortRequest validates the field against an allowed set of domain names — invalid fields throw IllegalArgumentException:

private static final Set<String> ALLOWED_FIELDS = Set.of("id", "name");

The mapping to SQL aliases happens in the infrastructure adapter:

private static final Map<String, String> FIELD_MAP = Map.of(
    "id",   "o.id",
    "name", "o.name"
);

This keeps the application layer free of SQL details. The allowed set and the field map are the only places to extend when new sortable fields are added.

PageQuery, PageResult, SortRequest have zero framework dependencies — copy them into any Java project.

Tests

Integration tests in src/test/java cover pagination correctness, sorting by single and multiple fields, default sort order, and SQL injection protection via the whitelist.

Related

• persistence-flat-pagination-jdbc — pagination only, no sorting
• persistence-graph-pagination-jdbc — pagination over a multi-level object graph

Run

./mvnw spring-boot:run