feat: support transaction (#176)

* feat: support transaction * feat: add tx options * feat: transaction return error * feat: replace enforcer to interface IEnforcer; reload policy at the end of transaction * Update adapter.go * feat: add to README about the new transaction usage Co-authored-by: Yang Luo <[email protected]>
casbin · Aug 28, 2022 · e1dae28 · e1dae28
1 parent e137c23
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diff --git a/README.md b/README.md
@@ -124,7 +124,31 @@ func main() {
 	e.SavePolicy()
 }
 ```
+## Transaction
+You can modify policies within a transaction.See example:
+```go
+package main
 
+func main() {
+	a, err := NewAdapterByDB(db)
+	e, _ := casbin.NewEnforcer("examples/rbac_model.conf", a)
+	err = e.GetAdapter().(*Adapter).Transaction(e, func(e casbin.IEnforcer) error {
+		_, err := e.AddPolicy("jack", "data1", "write")
+		if err != nil {
+			return err
+		}
+		_, err = e.AddPolicy("jack", "data2", "write")
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		// handle if transaction failed
+		return
+	}
+}
+```
 ## Getting Help
 
 - [Casbin](https://github.com/casbin/casbin)

diff --git a/adapter.go b/adapter.go
@@ -16,11 +16,13 @@ package gormadapter
 
 import (
 	"context"
+	"database/sql"
 	"errors"
 	"fmt"
 	"runtime"
 	"strings"
 
+	"github.com/casbin/casbin/v2"
 	"github.com/casbin/casbin/v2/model"
 	"github.com/casbin/casbin/v2/persist"
 	"github.com/glebarez/sqlite"
@@ -611,6 +613,33 @@ func (a *Adapter) AddPolicies(sec string, ptype string, rules [][]string) error
 	return a.db.Create(&lines).Error
 }
 
+// Transaction perform a set of operations within a transaction
+func (a *Adapter) Transaction(e casbin.IEnforcer, fc func(casbin.IEnforcer) error, opts ...*sql.TxOptions) error {
+	var err error
+	oriAdapter := a.db
+	// reload policy from database to sync with the transaction
+	defer func() {
+		e.SetAdapter(&Adapter{db: oriAdapter})
+		err = e.LoadPolicy()
+		if err != nil {
+			panic(err)
+		}
+	}()
+	copyDB := *a.db
+	tx := copyDB.Begin(opts...)
+	b := &Adapter{db: tx}
+	// copy enforcer to set the new adapter with transaction tx
+	copyEnforcer := e
+	copyEnforcer.SetAdapter(b)
+	err = fc(copyEnforcer)
+	if err != nil {
+		tx.Rollback()
+		return err
+	}
+	err = tx.Commit().Error
+	return err
+}
+
 // RemovePolicies removes multiple policy rules from the storage.
 func (a *Adapter) RemovePolicies(sec string, ptype string, rules [][]string) error {
 	return a.db.Transaction(func(tx *gorm.DB) error {

diff --git a/adapter_test.go b/adapter_test.go
@@ -628,3 +628,23 @@ func TestAddPolicies(t *testing.T) {
 
 	testGetPolicy(t, e, [][]string{{"alice", "data1", "read"}, {"bob", "data2", "write"}, {"data2_admin", "data2", "read"}, {"data2_admin", "data2", "write"}, {"jack", "data1", "read"}, {"jack2", "data1", "read"}})
 }
+
+func TestTransaction(t *testing.T) {
+	a := initAdapter(t, "mysql", "root:@tcp(127.0.0.1:3306)/", "casbin", "casbin_rule")
+	e, _ := casbin.NewEnforcer("examples/rbac_model.conf", a)
+	err := e.GetAdapter().(*Adapter).Transaction(e, func(e casbin.IEnforcer) error {
+		_, err := e.AddPolicy("jack", "data1", "write")
+		if err != nil {
+			return err
+		}
+		_, err = e.AddPolicy("jack", "data2", "write")
+		//err = errors.New("some error")
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		return
+	}
+}