entc: blob storage support

dialect/sql/schema/mysql.go

@@ -135,6 +135,8 @@ func (d *MySQL) atTypeC(c1 *Column, c2 *schema.Column) error {
 	switch c1.Type {
 	case field.TypeBool:
 		t = &schema.BoolType{T: "boolean"}
+	case field.TypeBlob:
+		return fmt.Errorf("blob fields are not stored in the database")
 	case field.TypeInt8:
 		t = &schema.IntegerType{T: mysql.TypeTinyInt}
 	case field.TypeUint8:

dialect/sql/schema/postgres.go

@@ -113,6 +113,8 @@ func (d *Postgres) atTypeC(c1 *Column, c2 *schema.Column) error {
 	}
 	var t schema.Type
 	switch c1.Type {
+	case field.TypeBlob:
+		return fmt.Errorf("blob fields are not stored in the database")
 	case field.TypeBool:
 		t = &schema.BoolType{T: postgres.TypeBoolean}
 	case field.TypeUint8, field.TypeInt8, field.TypeInt16:

dialect/sql/schema/sqlite.go

@@ -114,6 +114,8 @@ func (d *SQLite) atTypeC(c1 *Column, c2 *schema.Column) error {
 	}
 	var t schema.Type
 	switch c1.Type {
+	case field.TypeBlob:
+		return fmt.Errorf("blob fields are not stored in the database")
 	case field.TypeBool:
 		t = &schema.BoolType{T: "bool"}
 	case field.TypeInt8, field.TypeUint8, field.TypeInt16, field.TypeUint16, field.TypeInt32,

dialect/sql/sqlgraph/blob.go

@@ -0,0 +1,74 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
+package sqlgraph
+
+import (
+	"context"
+
+	"entgo.io/ent"
+	"entgo.io/ent/dialect"
+	"entgo.io/ent/dialect/sql"
+)
+
+// BlobSpec configures SQL-level blob key queries and implements [ent.BlobQuerier].
+type BlobSpec struct {
+	Driver    dialect.Driver
+	Table     string
+	Columns   map[string]string // field name -> key column name
+	Predicate func(*sql.Selector)
+}
+
+// QueryBlobKeys implements [ent.BlobQuerier].
+// If fields is nil, all columns are queried (for deletes);
+// otherwise only the named fields are queried.
+func (s *BlobSpec) QueryBlobKeys(ctx context.Context, fields []string) ([]ent.BlobKey, error) {
+	cols := s.Columns
+	if len(fields) > 0 {
+		cols = make(map[string]string, len(fields))
+		for _, f := range fields {
+			if c, ok := s.Columns[f]; ok {
+				cols[f] = c
+			}
+		}
+	}
+	if len(cols) == 0 {
+		return nil, nil
+	}
+	names := make([]string, 0, len(cols))
+	colNames := make([]string, 0, len(cols))
+	for field, col := range cols {
+		names = append(names, field)
+		colNames = append(colNames, col)
+	}
+	selector := sql.Dialect(s.Driver.Dialect()).
+		Select(colNames...).
+		From(sql.Table(s.Table))
+	if s.Predicate != nil {
+		s.Predicate(selector)
+	}
+	query, args := selector.Query()
+	rows := &sql.Rows{}
+	if err := s.Driver.Query(ctx, query, args, rows); err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var keys []ent.BlobKey
+	for rows.Next() {
+		vals := make([]*string, len(colNames))
+		ptrs := make([]any, len(colNames))
+		for i := range vals {
+			ptrs[i] = &vals[i]
+		}
+		if err := rows.Scan(ptrs...); err != nil {
+			return nil, err
+		}
+		for i, v := range vals {
+			if v != nil && *v != "" {
+				keys = append(keys, ent.BlobKey{Field: names[i], Key: *v})
+			}
+		}
+	}
+	return keys, rows.Err()
+}