uptrace · j2gg0s · Jan 14, 2025 · Jan 13, 2025
diff --git a/dialect/feature/feature.go b/dialect/feature/feature.go
@@ -1,6 +1,11 @@
 package feature
 
-import "github.com/uptrace/bun/internal"
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/uptrace/bun/internal"
+)
 
 type Feature = internal.Flag
 
@@ -35,4 +40,55 @@ const (
 	UpdateOrderLimit // UPDATE ... ORDER BY ... LIMIT ...
 	DeleteOrderLimit // DELETE ... ORDER BY ... LIMIT ...
 	DeleteReturning
+	AlterColumnExists // ADD/DROP COLUMN IF NOT EXISTS/IF EXISTS
 )
+
+type NotSupportError struct {
+	Flag Feature
+}
+
+func (err *NotSupportError) Error() string {
+	name, ok := flag2str[err.Flag]
+	if !ok {
+		name = strconv.FormatInt(int64(err.Flag), 10)
+	}
+	return fmt.Sprintf("bun: feature %s is not supported by current dialect", name)
+}
+
+func NewNotSupportError(flag Feature) *NotSupportError {
+	return &NotSupportError{Flag: flag}
+}
+
+var flag2str = map[Feature]string{
+	CTE:                  "CTE",
+	WithValues:           "WithValues",
+	Returning:            "Returning",
+	InsertReturning:      "InsertReturning",
+	Output:               "Output",
+	DefaultPlaceholder:   "DefaultPlaceholder",
+	DoubleColonCast:      "DoubleColonCast",
+	ValuesRow:            "ValuesRow",
+	UpdateMultiTable:     "UpdateMultiTable",
+	InsertTableAlias:     "InsertTableAlias",
+	UpdateTableAlias:     "UpdateTableAlias",
+	DeleteTableAlias:     "DeleteTableAlias",
+	AutoIncrement:        "AutoIncrement",
+	Identity:             "Identity",
+	TableCascade:         "TableCascade",
+	TableIdentity:        "TableIdentity",
+	TableTruncate:        "TableTruncate",
+	InsertOnConflict:     "InsertOnConflict",
+	InsertOnDuplicateKey: "InsertOnDuplicateKey",
+	InsertIgnore:         "InsertIgnore",
+	TableNotExists:       "TableNotExists",
+	OffsetFetch:          "OffsetFetch",
+	SelectExists:         "SelectExists",
+	UpdateFromTable:      "UpdateFromTable",
+	MSSavepoint:          "MSSavepoint",
+	GeneratedIdentity:    "GeneratedIdentity",
+	CompositeIn:          "CompositeIn",
+	UpdateOrderLimit:     "UpdateOrderLimit",
+	DeleteOrderLimit:     "DeleteOrderLimit",
+	DeleteReturning:      "DeleteReturning",
+	AlterColumnExists:    "AlterColumnExists",
+}
diff --git a/dialect/pgdialect/dialect.go b/dialect/pgdialect/dialect.go
@@ -53,7 +53,8 @@ func New(opts ...DialectOption) *Dialect {
 		feature.SelectExists |
 		feature.GeneratedIdentity |
 		feature.CompositeIn |
-		feature.DeleteReturning
+		feature.DeleteReturning |
+		feature.AlterColumnExists
 
 	for _, opt := range opts {
 		opt(d)

diff --git a/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-168 b/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-168
@@ -1 +1 @@
-bun: order is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-169 b/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-169
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-170 b/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-170
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-171 b/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-171
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature UpdateOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-172 b/internal/dbtest/testdata/snapshots/TestQuery-mssql2019-172
@@ -1 +1 @@
-bun: returning is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-mysql5-172 b/internal/dbtest/testdata/snapshots/TestQuery-mysql5-172
@@ -1 +1 @@
-bun: returning is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-mysql8-172 b/internal/dbtest/testdata/snapshots/TestQuery-mysql8-172
@@ -1 +1 @@
-bun: returning is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-pg-168 b/internal/dbtest/testdata/snapshots/TestQuery-pg-168
@@ -1 +1 @@
-bun: order is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-pg-169 b/internal/dbtest/testdata/snapshots/TestQuery-pg-169
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-pg-170 b/internal/dbtest/testdata/snapshots/TestQuery-pg-170
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-pg-171 b/internal/dbtest/testdata/snapshots/TestQuery-pg-171
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature UpdateOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-pgx-168 b/internal/dbtest/testdata/snapshots/TestQuery-pgx-168
@@ -1 +1 @@
-bun: order is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-pgx-169 b/internal/dbtest/testdata/snapshots/TestQuery-pgx-169
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-pgx-170 b/internal/dbtest/testdata/snapshots/TestQuery-pgx-170
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-pgx-171 b/internal/dbtest/testdata/snapshots/TestQuery-pgx-171
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature UpdateOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-sqlite-168 b/internal/dbtest/testdata/snapshots/TestQuery-sqlite-168
@@ -1 +1 @@
-bun: order is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-sqlite-169 b/internal/dbtest/testdata/snapshots/TestQuery-sqlite-169
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-sqlite-170 b/internal/dbtest/testdata/snapshots/TestQuery-sqlite-170
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature DeleteOrderLimit is not supported by current dialect
diff --git a/internal/dbtest/testdata/snapshots/TestQuery-sqlite-171 b/internal/dbtest/testdata/snapshots/TestQuery-sqlite-171
@@ -1 +1 @@
-bun: limit is not supported for current dialect
+bun: feature UpdateOrderLimit is not supported by current dialect
diff --git a/query_column_add.go b/query_column_add.go
@@ -5,6 +5,7 @@ import (
 	"database/sql"
 	"fmt"
 
+	"github.com/uptrace/bun/dialect/feature"
 	"github.com/uptrace/bun/internal"
 	"github.com/uptrace/bun/schema"
 )
@@ -133,6 +134,10 @@ func (q *AddColumnQuery) AppendQuery(fmter schema.Formatter, b []byte) (_ []byte
 //------------------------------------------------------------------------------
 
 func (q *AddColumnQuery) Exec(ctx context.Context, dest ...interface{}) (sql.Result, error) {
+	if q.ifNotExists && !q.hasFeature(feature.AlterColumnExists) {
+		return nil, feature.NewNotSupportError(feature.AlterColumnExists)
+	}
+
 	queryBytes, err := q.AppendQuery(q.db.fmter, q.db.makeQueryBytes())
 	if err != nil {
 		return nil, err

diff --git a/query_delete.go b/query_delete.go
@@ -128,7 +128,7 @@ func (q *DeleteQuery) WhereAllWithDeleted() *DeleteQuery {
 
 func (q *DeleteQuery) Order(orders ...string) *DeleteQuery {
 	if !q.hasFeature(feature.DeleteOrderLimit) {
-		q.err = errors.New("bun: order is not supported for current dialect")
+		q.err = feature.NewNotSupportError(feature.DeleteOrderLimit)
 		return q
 	}
 	q.addOrder(orders...)
@@ -137,7 +137,7 @@ func (q *DeleteQuery) Order(orders ...string) *DeleteQuery {
 
 func (q *DeleteQuery) OrderExpr(query string, args ...interface{}) *DeleteQuery {
 	if !q.hasFeature(feature.DeleteOrderLimit) {
-		q.err = errors.New("bun: order is not supported for current dialect")
+		q.err = feature.NewNotSupportError(feature.DeleteOrderLimit)
 		return q
 	}
 	q.addOrderExpr(query, args...)
@@ -152,7 +152,7 @@ func (q *DeleteQuery) ForceDelete() *DeleteQuery {
 // ------------------------------------------------------------------------------
 func (q *DeleteQuery) Limit(n int) *DeleteQuery {
 	if !q.hasFeature(feature.DeleteOrderLimit) {
-		q.err = errors.New("bun: limit is not supported for current dialect")
+		q.err = feature.NewNotSupportError(feature.DeleteOrderLimit)
 		return q
 	}
 	q.setLimit(n)
@@ -166,7 +166,7 @@ func (q *DeleteQuery) Limit(n int) *DeleteQuery {
 // To suppress the auto-generated RETURNING clause, use `Returning("NULL")`.
 func (q *DeleteQuery) Returning(query string, args ...interface{}) *DeleteQuery {
 	if !q.hasFeature(feature.DeleteReturning) {
-		q.err = errors.New("bun: returning is not supported for current dialect")
+		q.err = feature.NewNotSupportError(feature.DeleteOrderLimit)
 		return q
 	}
 

diff --git a/query_update.go b/query_update.go
@@ -207,7 +207,7 @@ func (q *UpdateQuery) WhereAllWithDeleted() *UpdateQuery {
 // ------------------------------------------------------------------------------
 func (q *UpdateQuery) Order(orders ...string) *UpdateQuery {
 	if !q.hasFeature(feature.UpdateOrderLimit) {
-		q.err = errors.New("bun: order is not supported for current dialect")
+		q.err = feature.NewNotSupportError(feature.UpdateOrderLimit)
 		return q
 	}
 	q.addOrder(orders...)
@@ -216,7 +216,7 @@ func (q *UpdateQuery) Order(orders ...string) *UpdateQuery {
 
 func (q *UpdateQuery) OrderExpr(query string, args ...interface{}) *UpdateQuery {
 	if !q.hasFeature(feature.UpdateOrderLimit) {
-		q.err = errors.New("bun: order is not supported for current dialect")
+		q.err = feature.NewNotSupportError(feature.UpdateOrderLimit)
 		return q
 	}
 	q.addOrderExpr(query, args...)
@@ -225,7 +225,7 @@ func (q *UpdateQuery) OrderExpr(query string, args ...interface{}) *UpdateQuery
 
 func (q *UpdateQuery) Limit(n int) *UpdateQuery {
 	if !q.hasFeature(feature.UpdateOrderLimit) {
-		q.err = errors.New("bun: limit is not supported for current dialect")
+		q.err = feature.NewNotSupportError(feature.UpdateOrderLimit)
 		return q
 	}
 	q.setLimit(n)
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		bun: order is not supported for current dialect
		bun: feature DeleteOrderLimit is not supported by current dialect
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		bun: limit is not supported for current dialect
		bun: feature DeleteOrderLimit is not supported by current dialect
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		bun: limit is not supported for current dialect
		bun: feature UpdateOrderLimit is not supported by current dialect
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		bun: returning is not supported for current dialect
		bun: feature DeleteOrderLimit is not supported by current dialect