Migration Guide

This guide helps you migrate between Bevy versions when using mevy. The key principle: mevy handles API differences automatically. You only need to change the version feature in Cargo.toml.

Bevy 0.18

Update your Cargo.toml:

mevy = { version = "0.3", features = ["0.18"] }

All entity!{} features work with Bevy 0.18.

API differences mevy handles automatically (for mevy_ui and mevy_core):

• border_radius now writes to Node::border_radius instead of BorderRadius
• line_height now uses a separate LineHeight component instead of TextFont::line_height
• Observer entity access uses trigger.event_target() (not trigger.target() or trigger.entity())

Bevy 0.17

Update your Cargo.toml:

mevy = { version = "0.3", features = ["0.17"] }

No code changes needed. Key changes mevy handles automatically:

• Observer triggers changed from Trigger<T> to On<T>
• Entity access changed from trigger.target() (0.16) to trigger.event_target() (0.17+)

Bevy 0.16

Update your Cargo.toml:

mevy = { version = "0.3", features = ["0.16"] }

No code changes needed. Key changes mevy handles automatically:

• BoxShadow changed from a direct struct to Vec<ShadowStyle>
• Child relationships use ChildOf instead of set_parent()
• Observer entity access uses trigger.target() (not trigger.entity() or trigger.event_target())

Bevy 0.15

Update your Cargo.toml:

mevy = { version = "0.3", features = ["0.15"] }

No code changes needed. Key differences in Bevy 0.15:

• ChildBuilder uses .parent_entity() and .spawn() instead of .target_entity() and .commands_mut()
• BorderColor is a single Srgba value, not per-edge
• Observer entity access uses trigger.entity() (not trigger.target() or trigger.event_target())

Version Support Matrix

Tips

1. Always pin your Bevy version — never omit the version feature.
2. Test with your target Bevy version — macro expansions differ between versions.
3. Check the changelog for breaking changes between mevy versions.