feat(templates): scaffold module migrations

ignite/templates/module/create/files/base/x/{{moduleName}}/keeper/migrate.go.plush

@@ -0,0 +1,15 @@
+package keeper
+
+// Migrator is a struct for handling in-place store migrations.
+type Migrator struct {
+	keeper *Keeper
+}
+
+// NewMigrator returns a new Migrator.
+func NewMigrator(keeper *Keeper) Migrator {
+	return Migrator{
+		keeper: keeper,
+	}
+}
+
+// this line is used by starport scaffolding # migrations/migrator

ignite/templates/module/create/files/base/x/{{moduleName}}/module/module.go.plush

@@ -132,6 +132,10 @@ func NewAppModule(
 func (am AppModule) RegisterServices(cfg module.Configurator) {
     types.RegisterMsgServer(cfg.MsgServer(), keeper.NewMsgServerImpl(am.keeper))
     types.RegisterQueryServer(cfg.QueryServer(), am.keeper)
+
+	m := keeper.NewMigrator(am.keeper)
+	_ = m
+	// this line is used by starport scaffolding # migrations/register
 }
 
 // RegisterInvariants registers the invariants of the module. If an invariant deviates from its predicted value, the InvariantRegistry triggers appropriate logic (most often the chain will be halted)

ignite/templates/module/create/files/migrations/x/{{moduleName}}/migrations/{{num}}/migrate.go.plush

@@ -0,0 +1,14 @@
+package {{ num }}
+
+import (
+	"context"
+
+	corestoretypes "cosmossdk.io/core/store"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+)
+
+// MigrateStore migrates the module to consensus version {{ num }}.
+func MigrateStore(ctx context.Context, storeService corestoretypes.KVStoreService, cdc codec.BinaryCodec) {
+	// Insert {{ num }} migration here.
+}

ignite/templates/module/placeholders.go

@@ -27,4 +27,8 @@ const (
 	PlaceholderTypesGenesisValidField = "// this line is used by starport scaffolding # types/genesis/validField"
 	PlaceholderGenesisTestState       = "// this line is used by starport scaffolding # genesis/test/state"
 	PlaceholderGenesisTestAssert      = "// this line is used by starport scaffolding # genesis/test/assert"
+
+	// Migrations
+	PlaceholderMigrationsRegister = "// this line is used by starport scaffolding # migrations/register"
+	PlaceholderMigrationsMigrator = "// this line is used by starport scaffolding # migrations/migrator"
 )