Migration & PostMig

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Version compatibility system for snapshots with post-load migrations.

Overview

Migrations enable:

  • Version Compatibility: Load old snapshot formats
  • Data Transformation: Convert between component versions
  • Post-Load Processing: Apply migrations after loading
  • Stable IDs: Maintain entity relationships

How It Works

Migration Process

Load Snapshot
    ↓
Detect Version
    ↓
Apply Migrations
    ↓
Transform Components
    ↓
World State Restored

Migration Registration

// Register migration
world.RegisterMigration<OldComponent, NewComponent>((old) => new NewComponent
{
    // Convert old to new
    Field = old.OldField,
    NewField = CalculateNewField(old)
});

Examples

Component Migration

// Old component
public struct OldHealth
{
    public int CurrentHP;
    public int MaxHP;
}

// New component
public struct Health
{
    public float Current;
    public float Max;
}

// Register migration
world.RegisterMigration<OldHealth, Health>((old) => new Health
{
    Current = old.CurrentHP,
    Max = old.MaxHP
});

// Load snapshot (migration applied automatically)
world.Load(stream);

See Also

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