zeroFruit

package keeper // migrations.go

type Migrator struct {
    keeper Keeper
}

func NewMigrator(keeper Keeper) Migrator {
    return Migrator{keeper: keeper}
}

zeroFruit

x
├── foo
│   ├── keepers
│   │   └── migrations.go
│   ├── migrations
│   │   ├── v1
│   │   │   ├── tx.pb.go
│   │   │   └── ...
│   │   └── v2
│   │       └── migrations.go

zeroFruit

package v2 // upgrades.go

var DenomMetadata = banktypes.Metadata{...}

func CreateUpgradeHandler(
    mm *module.Manager,
    configurator module.Configurator,
    bk bankkeeper.Keeper,
) upgradetypes.UpgradeHandler {
    return func(ctx sdk.Context, plan upgradetypes.Plan, vm module.VersionMap) (module.VersionMap, error) {

zeroFruit

package app // app.go

func NewSimApp(...) *SimApp {

    // setupUpgradeHandlers should be called before `LoadLatestVersion()`
    // because StoreLoad is sealed after that
    app.setupUpgradeHandlers(configurator, app.BankKeeper)
    
    if loadLatest {
        if err := app.LoadLatestVersion(); err != nil {

zeroFruit

package app // upgrades.go

func (app *App) setupUpgradeHandlers(
    configurator module.Configurator,
    ...
) {
    app.UpgradeKeeper.SetUpgradeHandler(
        v2.UpgradeName,
        v2.CreateUpgradeHandler(app.mm, configurator, ...),
    )

zeroFruit

package v2 // upgrades.go

func CreateUpgradeHandler(
    mm *module.Manager,
    configurator module.Configurator,
    ...
) upgradetypes.UpgradeHandler {
    return func(ctx sdk.Context, plan upgradetypes.Plan, vm module.VersionMap) (module.VersionMap, error) {
        ...
        

zeroFruit

package v2 // constants.go

const (
    UpgradeName = "v2.0.0"
    ...
)

zeroFruit

. # application project root
├── app
│   ├── upgrades
│   │   ├── v2
│   │   │   ├── constants.go 
│   │   │   └── upgrades.go
│   │   └── ...
│   ├── app.go
│   └── upgrades.go
└── ...

zeroFruit

func (am AppModule) BeginBlock(ctx sdk.Context, req abci.RequestBeginBlock) {
    BeginBlocker(am.keeper, ctx, req)
}

func BeginBlocker(k keeper.Keeper, ctx sdk.Context, _ abci.RequestBeginBlock) {
    plan, found := k.GetUpgradePlan(ctx)
    ...
    if !found {
        return
    }

zeroFruit

// VersionMap is a map of moduleName -> version
type VersionMap map[string]uint64