feat: add Plan.IsExclusive field for single subscription enforcement (#5004)

controllers/subscription.go

@@ -16,6 +16,7 @@ package controllers
 
 import (
 	"encoding/json"
+	"fmt"
 
 	"github.com/beego/beego/v2/core/utils/pagination"
 	"github.com/casdoor/casdoor/object"
@@ -150,6 +151,26 @@ func (c *ApiController) AddSubscription() {
 		return
 	}
 
+	// Check if plan restricts user to one subscription
+	if subscription.Plan != "" {
+		plan, err := object.GetPlan(util.GetId(subscription.Owner, subscription.Plan))
+		if err != nil {
+			c.ResponseError(err.Error())
+			return
+		}
+		if plan != nil && plan.IsExclusive {
+			hasSubscription, err := object.HasActiveSubscriptionForPlan(subscription.Owner, subscription.User, subscription.Plan)
+			if err != nil {
+				c.ResponseError(err.Error())
+				return
+			}
+			if hasSubscription {
+				c.ResponseError(fmt.Sprintf("User already has an active subscription for plan: %s", subscription.Plan))
+				return
+			}
+		}
+	}
+
 	c.Data["json"] = wrapActionResponse(object.AddSubscription(&subscription))
 	c.ServeJSON()
 }

object/order_pay.go

@@ -179,6 +179,17 @@ func PayOrder(providerName, host, paymentEnv string, order *Order, lang string)
 			return nil, nil, fmt.Errorf("the plan: %s does not exist", productInfo.PlanName)
 		}
 
+		// Check if plan restricts user to one subscription
+		if plan.IsExclusive {
+			hasSubscription, err := HasActiveSubscriptionForPlan(owner, user.Name, plan.Name)
+			if err != nil {
+				return nil, nil, err
+			}
+			if hasSubscription {
+				return nil, nil, fmt.Errorf("user already has an active subscription for plan: %s", plan.Name)
+			}
+		}
+
 		sub, err := NewSubscription(owner, user.Name, plan.Name, paymentName, plan.Period)
 		if err != nil {
 			return nil, nil, err

object/plan.go

@@ -35,6 +35,7 @@ type Plan struct {
 	Product          string   `xorm:"varchar(100)" json:"product"`
 	PaymentProviders []string `xorm:"varchar(100)" json:"paymentProviders"` // payment providers for related product
 	IsEnabled        bool     `json:"isEnabled"`
+	IsExclusive      bool     `json:"isExclusive"` // if true, a user can only have at most one subscription of this plan
 
 	Role    string   `xorm:"varchar(100)" json:"role"`
 	Options []string `xorm:"-" json:"options"`

object/subscription.go

@@ -217,6 +217,26 @@ func GetSubscription(id string) (*Subscription, error) {
 	return getSubscription(owner, name)
 }
 
+func HasActiveSubscriptionForPlan(owner, userName, planName string) (bool, error) {
+	subscriptions := []*Subscription{}
+	err := ormer.Engine.Find(&subscriptions, &Subscription{Owner: owner, User: userName, Plan: planName})
+	if err != nil {
+		return false, err
+	}
+
+	for _, sub := range subscriptions {
+		err = sub.UpdateState()
+		if err != nil {
+			return false, err
+		}
+		// Check if subscription is active, upcoming, or pending (not expired, error, or suspended)
+		if sub.State == SubStateActive || sub.State == SubStateUpcoming || sub.State == SubStatePending {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
 func UpdateSubscription(id string, subscription *Subscription) (bool, error) {
 	owner, name, err := util.GetOwnerAndNameFromIdWithError(id)
 	if err != nil {

web/src/PlanEditPage.js

@@ -260,6 +260,16 @@ class PlanEditPage extends React.Component {
             }} />
           </Col>
         </Row>
+        <Row style={{marginTop: "20px"}} >
+          <Col style={{marginTop: "5px"}} span={(Setting.isMobile()) ? 19 : 2}>
+            {Setting.getLabel(i18next.t("plan:Is exclusive"), i18next.t("plan:Is exclusive - Tooltip"))} :
+          </Col>
+          <Col span={1} >
+            <Switch checked={this.state.plan.isExclusive} disabled={isViewMode} onChange={checked => {
+              this.updatePlanField("isExclusive", checked);
+            }} />
+          </Col>
+        </Row>
       </Card>
     );
   }