timeblocks 0.1.0

Reusable Django time block & recurrence engine.

timeblocks

A reusable Django library for creating and managing time blocks using safe, deterministic recurrence rules.

Designed for scheduling systems where correctness, idempotency, and data safety matter.

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Why timeblocks?

Most scheduling implementations break when:

• recurrence rules change
• slots are regenerated
• bookings must be preserved
• timezones drift
• duplicate slots appear

timeblocks solves these problems by enforcing strict invariants:

• slots are generated from immutable templates
• destructive operations are explicit and scoped
• locked (booked) slots are never modified
• regeneration is safe and idempotent
• all datetime values are normalized to UTC

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Core Concepts

SlotSeries (template)

A SlotSeries defines how slots should exist:

• start date
• time window
• recurrence rule
• termination condition

It does not generate slots by itself.

Slot (instance)

A Slot is a concrete time interval generated from a series.

Slots may be:

• open
• locked (e.g. booked)
• soft-deleted (historical)

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Supported Recurrence Types

• NONE — single occurrence
• DAILY — every N days
• WEEKLY — specific weekdays (e.g. Mon/Wed/Fri)
• WEEKDAY_MON_FRI — Monday to Friday

Additional recurrence types can be added safely without breaking existing data.

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Installation

pip install timeblocks

Add to Django settings:

INSTALLED_APPS = [
    ...
    "django.contrib.contenttypes",
    "timeblocks",
]

Run migrations:

python manage.py migrate

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Basic Usage

from datetime import date, time
from timeblocks.services.series_service import SeriesService

series = SeriesService.create_series(
    owner=user,
    data={
        "start_date": date(2025, 1, 1),
        "start_time": time(9, 0),
        "end_time": time(10, 0),
        "timezone": "UTC",
        "recurrence_type": "DAILY",
        "interval": 1,
        "end_type": "AFTER_OCCURRENCES",
        "occurrence_count": 5,
    },
)

This will create:

• one SlotSeries
• five Slot rows
• all timestamps normalized to UTC

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Regenerating Slots

When a recurrence rule changes, regenerate safely:

from timeblocks.services.series_service import SeriesService

SeriesService.regenerate_series(
    series=series,
    scope="future",  # or "all"
)

Regeneration Rules

• locked slots are never touched
• soft-deleted slots are preserved
• scope controls blast radius
• operation is atomic

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Cancelling a Series

from timeblocks.services.series_service import SeriesService

SeriesService.cancel_series(series=series)

Effects:

• series is deactivated
• future unlocked slots are soft-deleted
• past and locked slots remain intact

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Safety Guarantees

timeblocks enforces the following invariants:

• no duplicate slots per series
• locked slots are immutable
• destructive operations are explicit
• all writes are transactional
• no database-specific constraints are required

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What timeblocks Does NOT Do

• booking logic
• permissions
• notifications
• UI or API views

These belong in your application layer.

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Compatibility

• Django >= 3.2
• Python >= 3.8
• Database-agnostic (PostgreSQL, MySQL, SQLite)

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Versioning & Upgrades

timeblocks follows semantic versioning.

• PATCH releases fix bugs without changing behavior
• MINOR releases add new recurrence types or capabilities
• MAJOR releases may change behavior or contracts

Breaking changes are always documented in the changelog.