fix(api): non-existent tax code

Author: tothandras

openmeter/billing/charges/charge.go

@@ -385,7 +385,33 @@ func (c ChargeIntent) GetUniqueReferenceID() (*string, error) {
 	return nil, fmt.Errorf("invalid charge type: %s", c.t)
 }
 
-// Meta returns the shared meta.Intent embedded in every charge type.
+// TaxCodeID returns the intent's configured tax code ID.
+// It is empty when no tax code is set.
+func (i ChargeIntent) TaxCodeID() (string, error) {
+	switch i.t {
+	case meta.ChargeTypeFlatFee:
+		if i.flatFee == nil {
+			return "", fmt.Errorf("flat fee is nil")
+		}
+
+		return i.flatFee.TaxConfig.TaxCodeID, nil
+	case meta.ChargeTypeUsageBased:
+		if i.usageBased == nil {
+			return "", fmt.Errorf("usage based is nil")
+		}
+
+		return i.usageBased.TaxConfig.TaxCodeID, nil
+	case meta.ChargeTypeCreditPurchase:
+		if i.creditPurchase == nil {
+			return "", fmt.Errorf("credit purchase is nil")
+		}
+
+		return i.creditPurchase.TaxConfig.TaxCodeID, nil
+	}
+
+	return "", fmt.Errorf("unsupported charge type: %s", i.t)
+}
+
 // WithTaxCodeID returns a copy of the intent with TaxCodeID set to id.
 // Existing tax behavior and other intent fields are preserved.
 func (i ChargeIntent) WithTaxCodeID(id string) (ChargeIntent, error) {

openmeter/billing/charges/creditpurchase/adapter/charge.go

@@ -12,6 +12,7 @@ import (
 	"github.com/openmeterio/openmeter/openmeter/ent/db"
 	dbchargecreditpurchase "github.com/openmeterio/openmeter/openmeter/ent/db/chargecreditpurchase"
 	"github.com/openmeterio/openmeter/pkg/framework/entutils"
+	"github.com/openmeterio/openmeter/pkg/models"
 	"github.com/openmeterio/openmeter/pkg/pagination"
 	"github.com/openmeterio/openmeter/pkg/slicesx"
 )
@@ -89,6 +90,12 @@ func (a *adapter) CreateCharge(ctx context.Context, in creditpurchase.CreateChar
 
 		dbCreditPurchase, err := create.Save(ctx)
 		if err != nil {
+			if db.IsConstraintError(err) {
+				return creditpurchase.Charge{}, models.NewGenericPreConditionFailedError(
+					fmt.Errorf("charge references a resource that does not exist"),
+				)
+			}
+
 			return creditpurchase.Charge{}, err
 		}
 

openmeter/billing/charges/flatfee/adapter/charge.go

@@ -208,6 +208,12 @@ func (a *adapter) CreateCharges(ctx context.Context, in flatfee.CreateChargesInp
 
 		entities, err := tx.db.ChargeFlatFee.CreateBulk(creates...).Save(ctx)
 		if err != nil {
+			if db.IsConstraintError(err) {
+				return nil, models.NewGenericPreConditionFailedError(
+					fmt.Errorf("charge references a resource that does not exist"),
+				)
+			}
+
 			return nil, err
 		}
 

openmeter/billing/charges/service/create.go

@@ -21,6 +21,7 @@ import (
 	"github.com/openmeterio/openmeter/pkg/clock"
 	"github.com/openmeterio/openmeter/pkg/currencyx"
 	"github.com/openmeterio/openmeter/pkg/framework/transaction"
+	"github.com/openmeterio/openmeter/pkg/models"
 	"github.com/openmeterio/openmeter/pkg/ref"
 	"github.com/openmeterio/openmeter/pkg/slicesx"
 )
@@ -43,29 +44,9 @@ func (s *service) applyDefaultTaxCodes(ctx context.Context, namespace string, in
 	})
 
 	return slicesx.MapWithErr(intents, func(intent charges.ChargeIntent) (charges.ChargeIntent, error) {
-		var taxCodeID string
-
-		switch intent.Type() {
-		case meta.ChargeTypeFlatFee:
-			flatFee, err := intent.AsFlatFeeIntent()
-			if err != nil {
-				return charges.ChargeIntent{}, err
-			}
-			taxCodeID = flatFee.TaxConfig.TaxCodeID
-		case meta.ChargeTypeCreditPurchase:
-			creditPurchase, err := intent.AsCreditPurchaseIntent()
-			if err != nil {
-				return charges.ChargeIntent{}, err
-			}
-			taxCodeID = creditPurchase.TaxConfig.TaxCodeID
-		case meta.ChargeTypeUsageBased:
-			usageBased, err := intent.AsUsageBasedIntent()
-			if err != nil {
-				return charges.ChargeIntent{}, err
-			}
-			taxCodeID = usageBased.TaxConfig.TaxCodeID
-		default:
-			return charges.ChargeIntent{}, fmt.Errorf("unsupported charge type: %s", intent.Type())
+		taxCodeID, err := intent.TaxCodeID()
+		if err != nil {
+			return charges.ChargeIntent{}, err
 		}
 
 		if taxCodeID != "" {
@@ -87,6 +68,44 @@ func (s *service) applyDefaultTaxCodes(ctx context.Context, namespace string, in
 	})
 }
 
+// validateTaxCodesExist verifies every distinct non-empty tax code referenced by the intents
+// exists.
+func (s *service) validateTaxCodesExist(ctx context.Context, namespace string, intents charges.ChargeIntents) error {
+	seen := make(map[string]struct{}, len(intents))
+
+	for _, intent := range intents {
+		taxCodeID, err := intent.TaxCodeID()
+		if err != nil {
+			return err
+		}
+
+		if taxCodeID == "" {
+			continue
+		}
+
+		if _, ok := seen[taxCodeID]; ok {
+			continue
+		}
+		seen[taxCodeID] = struct{}{}
+
+		_, err = s.taxCodeService.GetTaxCode(ctx, taxcode.GetTaxCodeInput{
+			NamespacedID: models.NamespacedID{Namespace: namespace, ID: taxCodeID},
+		})
+		if err != nil {
+			if taxcode.IsTaxCodeNotFoundError(err) {
+				return models.NewGenericValidationError(
+					models.NewValidationError("tax_code_not_found", fmt.Sprintf("referenced tax code %q does not exist", taxCodeID)).
+						WithPathString("tax_config", "tax_code"),
+				)
+			}
+
+			return err
+		}
+	}
+
+	return nil
+}
+
 func (s *service) Create(ctx context.Context, input charges.CreateInput) (charges.Charges, error) {
 	result, err := s.create(ctx, input)
 	if err != nil {
@@ -127,6 +146,10 @@ func (s *service) create(ctx context.Context, input charges.CreateInput) (*charg
 		return nil, err
 	}
 
+	if err := s.validateTaxCodesExist(ctx, input.Namespace, input.Intents); err != nil {
+		return nil, err
+	}
+
 	result, err := transaction.Run(ctx, s.adapter, func(ctx context.Context) (*chargesWithInvoiceNowActions, error) {
 		intentsByType, err := input.Intents.ByType()
 		if err != nil {

openmeter/billing/charges/usagebased/adapter/charge.go

@@ -186,6 +186,12 @@ func (a *adapter) CreateCharges(ctx context.Context, in usagebased.CreateCharges
 
 		entities, err := tx.db.ChargeUsageBased.CreateBulk(creates...).Save(ctx)
 		if err != nil {
+			if db.IsConstraintError(err) {
+				return nil, models.NewGenericPreConditionFailedError(
+					fmt.Errorf("charge references a resource that does not exist"),
+				)
+			}
+
 			return nil, err
 		}
 

test/credits/creditgrant_test.go

@@ -31,6 +31,7 @@ import (
 	omtestutils "github.com/openmeterio/openmeter/openmeter/testutils"
 	"github.com/openmeterio/openmeter/pkg/clock"
 	"github.com/openmeterio/openmeter/pkg/datetime"
+	"github.com/openmeterio/openmeter/pkg/models"
 	billingtest "github.com/openmeterio/openmeter/test/billing"
 )
 
@@ -610,6 +611,30 @@ func (s *CreditGrantTestSuite) TestCreatePromotionalGrantPropagatesTaxConfigToCh
 	s.Equal(tc.ID, grant.Intent.TaxConfig.TaxCodeID)
 }
 
+// TestCreateGrantWithMissingTaxCodeFailsValidation verifies that referencing a non-existent tax code
+// is reported as a validation error.
+func (s *CreditGrantTestSuite) TestCreateGrantWithMissingTaxCodeFailsValidation() {
+	ctx := s.T().Context()
+	ns := s.GetUniqueNamespace("creditgrant-missing-taxcode")
+	s.ProvisionDefaultTaxCodes(ctx, ns)
+
+	cust := s.CreateLedgerBackedCustomer(ns, "test-subject")
+
+	_, err := s.CreditGrantService.Create(ctx, creditgrant.CreateInput{
+		Namespace:     ns,
+		CustomerID:    cust.ID,
+		Name:          "grant with missing tax code",
+		Currency:      USD,
+		Amount:        alpacadecimal.NewFromInt(10),
+		FundingMethod: creditgrant.FundingMethodNone,
+		TaxConfig: &productcatalog.TaxConfig{
+			TaxCodeID: lo.ToPtr("01KW0000000000000000000000"),
+		},
+	})
+	s.Require().Error(err)
+	s.True(models.IsGenericValidationError(err), "a reference to a non-existent tax code must be a validation error, got: %v", err)
+}
+
 func (s *CreditGrantTestSuite) mustCreatePromotionalCreditGrant(ctx context.Context, namespace string, customerID customer.CustomerID, name string, amount alpacadecimal.Decimal) creditpurchase.Charge {
 	s.T().Helper()