Unity依赖注入：子容器中FromScriptableObjectResource绑定失效

当使用Zenject的FromScriptableObjectResource在父容器绑定ModuleCameraGameConfig时，子容器内的ModuleCameraGame可以正常获取到配置；但把绑定语句移到子容器内部后，同一子容器里的ModuleCameraGame却无法获取该配置，求原因及解决办法。

正常运行的代码 #

public class CameraServiceInstaller : Installer<CameraServiceInstaller>
{
    public override void InstallBindings()
    {
        Container
            .Bind<ServiceCamera>()
            .FromSubContainerResolve()
            .ByInstaller<CameraServiceSubContainerInstaller>()
            .AsSingle();

        Container
            .Bind<ModuleCameraGameConfig>().FromScriptableObjectResource("Configs/ModuleCameraGameConfig").AsSingle();
    }
}

internal class CameraServiceSubContainerInstaller : Installer<CameraServiceSubContainerInstaller>
{
    public override void InstallBindings()
    {
        Container
            .Bind<ServiceCamera>()
            .AsSingle();
        Container
            .Bind<ModuleCameraGame>().FromComponentInHierarchy().AsSingle();
    }
}

无法运行的代码（ModuleCameraGame无法获取配置） #

public class CameraServiceInstaller : Installer<CameraServiceInstaller>
{
    public override void InstallBindings()
    {
        Container
            .Bind<ServiceCamera>()
            .FromSubContainerResolve()
            .ByInstaller<CameraServiceSubContainerInstaller>()
            .AsSingle();
    }
}

internal class CameraServiceSubContainerInstaller : Installer<CameraServiceSubContainerInstaller>
{
    public override void InstallBindings()
    {
        Container
            .Bind<ServiceCamera>()
            .AsSingle();
        Container
            .Bind<ModuleCameraGame>().FromComponentInHierarchy().AsSingle();

        Container
           .Bind<ModuleCameraGameConfig>().FromScriptableObjectResource("Configs/ModuleCameraGameConfig").AsSingle();
    }
}

原因分析 #

核心问题出在绑定顺序和FromComponentInHierarchy的解析时机：

• 异常代码中，ModuleCameraGame用FromComponentInHierarchy()绑定，Zenject会在绑定阶段立刻去场景中查找并初始化这个组件，此时子容器里的ModuleCameraGameConfig绑定还没执行，导致注入时找不到依赖。
• 正常代码中，父容器先完成配置绑定，子容器解析ModuleCameraGame时会向上遍历父容器的绑定表，所以能找到对应的配置。

解决方案 #

方案1：调整绑定顺序 #

在子容器中先绑定配置，再绑定需要依赖的组件，确保注入时依赖已经存在：

internal class CameraServiceSubContainerInstaller : Installer<CameraServiceSubContainerInstaller>
{
    public override void InstallBindings()
    {
        // 先绑定配置
        Container
           .Bind<ModuleCameraGameConfig>().FromScriptableObjectResource("Configs/ModuleCameraGameConfig").AsSingle();

        Container
            .Bind<ServiceCamera>()
            .AsSingle();
        Container
            .Bind<ModuleCameraGame>().FromComponentInHierarchy().AsSingle();
    }
}

方案2：延迟组件解析时机 #

给FromComponentInHierarchy()加上NonLazy()，让Zenject不在绑定阶段立即查找组件，而是等到第一次被注入或手动获取时再处理，此时配置已经完成绑定：

Container
    .Bind<ModuleCameraGame>().FromComponentInHierarchy().AsSingle().NonLazy();

内容的提问来源于stack exchange，提问作者Ilia Lataria