//InTransaction executes function in the db transaction and set it to the context
func InTransaction(context middleware.Context, dataStore db.DB, level transaction.Type, f func() error) error {
	if context["transaction"] != nil {
		return fmt.Errorf("cannot create nested transaction")
	}
	aTransaction, err := dataStore.Begin()
	if err != nil {
		return fmt.Errorf("cannot create transaction: %v", err)
	}
	defer aTransaction.Close()
	err = aTransaction.SetIsolationLevel(level)
	if err != nil {
		return fmt.Errorf("error when setting isolation level '%s': %s", level, err)
	}
	context["transaction"] = aTransaction

	err = f()
	if err != nil {
		return err
	}

	err = aTransaction.Commit()
	if err != nil {
		return fmt.Errorf("commit error : %s", err)
	}
	delete(context, "transaction")
	return nil
}

// DeleteResource deletes the resource specified by the schema and ID
func DeleteResource(context middleware.Context,
	dataStore db.DB,
	resourceSchema *schema.Schema,
	resourceID string,
) error {
	context["id"] = resourceID
	environmentManager := extension.GetManager()
	environment, ok := environmentManager.GetEnvironment(resourceSchema.ID)
	if !ok {
		return fmt.Errorf("No environment for schema")
	}
	auth := context["auth"].(schema.Authorization)
	policy, err := loadPolicy(context, "delete", strings.Replace(resourceSchema.GetSingleURL(), ":id", resourceID, 1), auth)
	if err != nil {
		return err
	}
	context["policy"] = policy
	preTransaction, err := dataStore.Begin()
	if err != nil {
		return fmt.Errorf("cannot create transaction: %v", err)
	}
	tenantIDs := policy.GetTenantIDFilter(schema.ActionDelete, auth.TenantID())
	filter := transaction.IDFilter(resourceID)
	if tenantIDs != nil {
		filter["tenant_id"] = tenantIDs
	}
	resource, fetchErr := preTransaction.Fetch(resourceSchema, filter)
	preTransaction.Close()

	if resource != nil {
		context["resource"] = resource.Data()
	}

	if err := extension.HandleEvent(context, environment, "pre_delete"); err != nil {
		return err
	}
	if fetchErr != nil {
		return ResourceError{err, "", NotFound}
	}
	if err := InTransaction(
		context, dataStore,
		transaction.GetIsolationLevel(resourceSchema, schema.ActionDelete),
		func() error {
			return DeleteResourceInTransaction(context, resourceSchema, resourceID)
		},
	); err != nil {
		return err
	}
	if err := extension.HandleEvent(context, environment, "post_delete"); err != nil {
		return err
	}
	return nil
}

//InTransaction executes function in the db transaction and set it to the context
func InTransaction(context middleware.Context, dataStore db.DB, f func() error) error {
	if context["transaction"] != nil {
		return fmt.Errorf("cannot create nested transaction")
	}
	aTransaction, err := dataStore.Begin()
	if err != nil {
		return fmt.Errorf("cannot create transaction: %v", err)
	}
	defer aTransaction.Close()
	context["transaction"] = aTransaction

	err = f()
	if err != nil {
		return err
	}

	err = aTransaction.Commit()
	if err != nil {
		return fmt.Errorf("commit error : %s", err)
	}
	delete(context, "transaction")
	return nil
}

// CreateOrUpdateResource updates resource if it existed and otherwise creates it and returns true.
func CreateOrUpdateResource(
	context middleware.Context,
	dataStore db.DB, identityService middleware.IdentityService,
	resourceSchema *schema.Schema,
	resourceID string, dataMap map[string]interface{},
) (bool, error) {
	auth := context["auth"].(schema.Authorization)

	//LoadPolicy
	policy, err := loadPolicy(context, "update", strings.Replace(resourceSchema.GetSingleURL(), ":id", resourceID, 1), auth)
	if err != nil {
		return false, err
	}

	preTransaction, err := dataStore.Begin()
	if err != nil {
		return false, fmt.Errorf("cannot create transaction: %v", err)
	}
	tenantIDs := policy.GetTenantIDFilter(schema.ActionUpdate, auth.TenantID())
	filter := transaction.IDFilter(resourceID)
	if tenantIDs != nil {
		filter["tenant_id"] = tenantIDs
	}
	_, fetchErr := preTransaction.Fetch(resourceSchema, filter)
	preTransaction.Close()

	if fetchErr != nil {
		dataMap["id"] = resourceID
		if err := CreateResource(context, dataStore, identityService, resourceSchema, dataMap); err != nil {
			return false, err
		}
		return true, err
	}

	return false, UpdateResource(context, dataStore, identityService, resourceSchema, resourceID, dataMap)
}

			Expect(server.Sync()).To(Succeed())

			_, err = sync.Fetch(networkResource.Path())
			Expect(err).To(HaveOccurred(), "Failed to sync db resource deletion to sync backend")
		})
	})

	Describe("Updating the state", func() {
		const (
			statePrefix      = "/state"
			monitoringPrefix = "/monitoring"
		)
		var (
			networkSchema   *schema.Schema
			networkResource *schema.Resource
			wrappedTestDB   db.DB
			possibleEvent   gohan_sync.Event
		)

		BeforeEach(func() {
			manager := schema.GetManager()
			var ok bool
			networkSchema, ok = manager.Schema("network")
			Expect(ok).To(BeTrue())
			network := getNetwork("Red", "red")
			var err error
			networkResource, err = manager.LoadResource("network", network)
			Expect(err).ToNot(HaveOccurred())
			wrappedTestDB = &srv.DbSyncWrapper{DB: testDB}
			tx, err := wrappedTestDB.Begin()
			defer tx.Close()

	"github.com/cloudwan/gohan/schema"
	"github.com/cloudwan/gohan/util"
	. "github.com/onsi/ginkgo"
	. "github.com/onsi/gomega"
)

var _ = Describe("Database operation test", func() {
	var (
		err error
		ok  bool

		conn   string
		dbType string

		manager          *schema.Manager
		networkSchema    *schema.Schema
		serverSchema     *schema.Schema
		networkResource1 *schema.Resource
		networkResource2 *schema.Resource
		subnetResource   *schema.Resource
		serverResource   *schema.Resource

		dataStore db.DB
	)

	BeforeEach(func() {
		manager = schema.GetManager()
		Expect(manager.LoadSchemaFromFile("../etc/schema/gohan.json")).To(Succeed())
	})

	AfterEach(func() {

//DBBegin starts transaction
func DBBegin(connection db.DB) (transaction.Transaction, error) {
	return connection.Begin()
}