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package pgdialect
import (
"context"
"fmt"
"strings"
"github.com/uptrace/bun"
"github.com/uptrace/bun/migrate"
"github.com/uptrace/bun/migrate/sqlschema"
"github.com/uptrace/bun/schema"
)
func (d *Dialect) NewMigrator(db *bun.DB, schemaName string) sqlschema.Migrator {
return &migrator{db: db, schemaName: schemaName, BaseMigrator: sqlschema.NewBaseMigrator(db)}
}
type migrator struct {
*sqlschema.BaseMigrator
db *bun.DB
schemaName string
}
var _ sqlschema.Migrator = (*migrator)(nil)
func (m *migrator) AppendSQL(b []byte, operation interface{}) (_ []byte, err error) {
fmter := m.db.Formatter()
// Append ALTER TABLE statement to the enclosed query bytes []byte.
appendAlterTable := func(query []byte, tableName string) []byte {
query = append(query, "ALTER TABLE "...)
query = m.appendFQN(fmter, query, tableName)
return append(query, " "...)
}
switch change := operation.(type) {
case *migrate.CreateTableOp:
return m.AppendCreateTable(b, change.Model)
case *migrate.DropTableOp:
return m.AppendDropTable(b, m.schemaName, change.TableName)
case *migrate.RenameTableOp:
b, err = m.renameTable(fmter, appendAlterTable(b, change.TableName), change)
case *migrate.RenameColumnOp:
b, err = m.renameColumn(fmter, appendAlterTable(b, change.TableName), change)
case *migrate.AddColumnOp:
b, err = m.addColumn(fmter, appendAlterTable(b, change.TableName), change)
case *migrate.DropColumnOp:
b, err = m.dropColumn(fmter, appendAlterTable(b, change.TableName), change)
case *migrate.AddPrimaryKeyOp:
b, err = m.addPrimaryKey(fmter, appendAlterTable(b, change.TableName), change.PrimaryKey)
case *migrate.ChangePrimaryKeyOp:
b, err = m.changePrimaryKey(fmter, appendAlterTable(b, change.TableName), change)
case *migrate.DropPrimaryKeyOp:
b, err = m.dropConstraint(fmter, appendAlterTable(b, change.TableName), change.PrimaryKey.Name)
case *migrate.AddUniqueConstraintOp:
b, err = m.addUnique(fmter, appendAlterTable(b, change.TableName), change)
case *migrate.DropUniqueConstraintOp:
b, err = m.dropConstraint(fmter, appendAlterTable(b, change.TableName), change.Unique.Name)
case *migrate.ChangeColumnTypeOp:
// If column changes to SERIAL, create sequence first.
// https://gist.github.com/oleglomako/185df689706c5499612a0d54d3ffe856
if !change.From.GetIsAutoIncrement() && change.To.GetIsAutoIncrement() {
change.To, b, err = m.createDefaultSequence(fmter, b, change)
}
b, err = m.changeColumnType(fmter, appendAlterTable(b, change.TableName), change)
case *migrate.AddForeignKeyOp:
b, err = m.addForeignKey(fmter, appendAlterTable(b, change.TableName()), change)
case *migrate.DropForeignKeyOp:
b, err = m.dropConstraint(fmter, appendAlterTable(b, change.TableName()), change.ConstraintName)
default:
return nil, fmt.Errorf("append sql: unknown operation %T", change)
}
if err != nil {
return nil, fmt.Errorf("append sql: %w", err)
}
return b, nil
}
func (m *migrator) appendFQN(fmter schema.Formatter, b []byte, tableName string) []byte {
return fmter.AppendQuery(b, "?.?", bun.Ident(m.schemaName), bun.Ident(tableName))
}
func (m *migrator) renameTable(fmter schema.Formatter, b []byte, rename *migrate.RenameTableOp) (_ []byte, err error) {
b = append(b, "RENAME TO "...)
b = fmter.AppendName(b, rename.NewName)
return b, nil
}
func (m *migrator) renameColumn(fmter schema.Formatter, b []byte, rename *migrate.RenameColumnOp) (_ []byte, err error) {
b = append(b, "RENAME COLUMN "...)
b = fmter.AppendName(b, rename.OldName)
b = append(b, " TO "...)
b = fmter.AppendName(b, rename.NewName)
return b, nil
}
func (m *migrator) addColumn(fmter schema.Formatter, b []byte, add *migrate.AddColumnOp) (_ []byte, err error) {
b = append(b, "ADD COLUMN "...)
b = fmter.AppendName(b, add.ColumnName)
b = append(b, " "...)
b, err = add.Column.AppendQuery(fmter, b)
if err != nil {
return nil, err
}
if add.Column.GetDefaultValue() != "" {
b = append(b, " DEFAULT "...)
b = append(b, add.Column.GetDefaultValue()...)
b = append(b, " "...)
}
if add.Column.GetIsIdentity() {
b = appendGeneratedAsIdentity(b)
}
return b, nil
}
func (m *migrator) dropColumn(fmter schema.Formatter, b []byte, drop *migrate.DropColumnOp) (_ []byte, err error) {
b = append(b, "DROP COLUMN "...)
b = fmter.AppendName(b, drop.ColumnName)
return b, nil
}
func (m *migrator) addPrimaryKey(fmter schema.Formatter, b []byte, pk sqlschema.PrimaryKey) (_ []byte, err error) {
b = append(b, "ADD PRIMARY KEY ("...)
b, _ = pk.Columns.AppendQuery(fmter, b)
b = append(b, ")"...)
return b, nil
}
func (m *migrator) changePrimaryKey(fmter schema.Formatter, b []byte, change *migrate.ChangePrimaryKeyOp) (_ []byte, err error) {
b, _ = m.dropConstraint(fmter, b, change.Old.Name)
b = append(b, ", "...)
b, _ = m.addPrimaryKey(fmter, b, change.New)
return b, nil
}
func (m *migrator) addUnique(fmter schema.Formatter, b []byte, change *migrate.AddUniqueConstraintOp) (_ []byte, err error) {
b = append(b, "ADD CONSTRAINT "...)
if change.Unique.Name != "" {
b = fmter.AppendName(b, change.Unique.Name)
} else {
// Default naming scheme for unique constraints in Postgres is <table>_<column>_key
b = fmter.AppendName(b, fmt.Sprintf("%s_%s_key", change.TableName, change.Unique.Columns))
}
b = append(b, " UNIQUE ("...)
b, _ = change.Unique.Columns.AppendQuery(fmter, b)
b = append(b, ")"...)
return b, nil
}
func (m *migrator) dropConstraint(fmter schema.Formatter, b []byte, name string) (_ []byte, err error) {
b = append(b, "DROP CONSTRAINT "...)
b = fmter.AppendName(b, name)
return b, nil
}
func (m *migrator) addForeignKey(fmter schema.Formatter, b []byte, add *migrate.AddForeignKeyOp) (_ []byte, err error) {
b = append(b, "ADD CONSTRAINT "...)
name := add.ConstraintName
if name == "" {
colRef := add.ForeignKey.From
columns := strings.Join(colRef.Column.Split(), "_")
name = fmt.Sprintf("%s_%s_fkey", colRef.TableName, columns)
}
b = fmter.AppendName(b, name)
b = append(b, " FOREIGN KEY ("...)
if b, err = add.ForeignKey.From.Column.AppendQuery(fmter, b); err != nil {
return b, err
}
b = append(b, ")"...)
b = append(b, " REFERENCES "...)
b = m.appendFQN(fmter, b, add.ForeignKey.To.TableName)
b = append(b, " ("...)
if b, err = add.ForeignKey.To.Column.AppendQuery(fmter, b); err != nil {
return b, err
}
b = append(b, ")"...)
return b, nil
}
// createDefaultSequence creates a SEQUENCE to back a serial column.
// Having a backing sequence is necessary to change column type to SERIAL.
// The updated Column's default is set to "nextval" of the new sequence.
func (m *migrator) createDefaultSequence(_ schema.Formatter, b []byte, op *migrate.ChangeColumnTypeOp) (_ sqlschema.Column, _ []byte, err error) {
var last int
if err = m.db.NewSelect().Table(op.TableName).
ColumnExpr("MAX(?)", op.Column).Scan(context.TODO(), &last); err != nil {
return nil, b, err
}
seq := op.TableName + "_" + op.Column + "_seq"
fqn := op.TableName + "." + op.Column
// A sequence that is OWNED BY a table will be dropped
// if the table is dropped with CASCADE action.
b = append(b, "CREATE SEQUENCE "...)
b = append(b, seq...)
b = append(b, " START WITH "...)
b = append(b, fmt.Sprint(last+1)...) // start with next value
b = append(b, " OWNED BY "...)
b = append(b, fqn...)
b = append(b, ";\n"...)
return &Column{
Name: op.To.GetName(),
SQLType: op.To.GetSQLType(),
VarcharLen: op.To.GetVarcharLen(),
DefaultValue: fmt.Sprintf("nextval('%s'::regclass)", seq),
IsNullable: op.To.GetIsNullable(),
IsAutoIncrement: op.To.GetIsAutoIncrement(),
IsIdentity: op.To.GetIsIdentity(),
}, b, nil
}
func (m *migrator) changeColumnType(fmter schema.Formatter, b []byte, colDef *migrate.ChangeColumnTypeOp) (_ []byte, err error) {
// alterColumn never re-assigns err, so there is no need to check for err != nil after calling it
var i int
appendAlterColumn := func() {
if i > 0 {
b = append(b, ", "...)
}
b = append(b, "ALTER COLUMN "...)
b = fmter.AppendName(b, colDef.Column)
i++
}
got, want := colDef.From, colDef.To
inspector := m.db.Dialect().(sqlschema.InspectorDialect)
if !inspector.CompareType(want, got) {
appendAlterColumn()
b = append(b, " SET DATA TYPE "...)
if b, err = want.AppendQuery(fmter, b); err != nil {
return b, err
}
}
// Column must be declared NOT NULL before identity can be added.
// Although PG can resolve the order of operations itself, we make this explicit in the query.
if want.GetIsNullable() != got.GetIsNullable() {
appendAlterColumn()
if !want.GetIsNullable() {
b = append(b, " SET NOT NULL"...)
} else {
b = append(b, " DROP NOT NULL"...)
}
}
if want.GetIsIdentity() != got.GetIsIdentity() {
appendAlterColumn()
if !want.GetIsIdentity() {
b = append(b, " DROP IDENTITY"...)
} else {
b = append(b, " ADD"...)
b = appendGeneratedAsIdentity(b)
}
}
if want.GetDefaultValue() != got.GetDefaultValue() {
appendAlterColumn()
if want.GetDefaultValue() == "" {
b = append(b, " DROP DEFAULT"...)
} else {
b = append(b, " SET DEFAULT "...)
b = append(b, want.GetDefaultValue()...)
}
}
return b, nil
}
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