axiom-sqlitedata-ref

SQLiteData Advanced Reference

Overview

Advanced query patterns and schema composition techniques for SQLiteData by Point-Free. Built on GRDB and StructuredQueries.

For core patterns (CRUD, CloudKit setup, @Table basics), see the axiom-sqlitedata discipline skill.

This reference covers advanced querying, schema composition, views, and custom aggregates.

Requires iOS 17+, Swift 6 strict concurrency Framework SQLiteData 1.4+

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Column Groups and Schema Composition

SQLiteData provides powerful tools for composing schema types, enabling reuse, better organization, and single-table inheritance patterns.

Column Groups

Group related columns into reusable types with @Selection:

// Define a reusable column group
@Selection
struct Timestamps {
    let createdAt: Date
    let updatedAt: Date?
}

// Use in multiple tables
@Table
nonisolated struct RemindersList: Identifiable {
    let id: UUID
    var title = ""
    let timestamps: Timestamps  // Embedded column group
}

@Table
nonisolated struct Reminder: Identifiable {
    let id: UUID
    var title = ""
    var isCompleted = false
    let timestamps: Timestamps  // Same group, reused
}

Important: SQLite has no concept of grouped columns. Flatten all groupings in your CREATE TABLE:

CREATE TABLE "remindersLists" (
    "id" TEXT PRIMARY KEY NOT NULL DEFAULT (uuid()),
    "title" TEXT NOT NULL DEFAULT '',
    "createdAt" TEXT NOT NULL,
    "updatedAt" TEXT
) STRICT

Querying Column Groups

Access fields inside groups with dot syntax:

// Query a field inside the group
RemindersList
    .where { $0.timestamps.createdAt <= cutoffDate }
    .fetchAll(db)

// Compare entire group (flattens to tuple in SQL)
RemindersList
    .where {
        $0.timestamps <= Timestamps(createdAt: date1, updatedAt: date2)
    }